JP7582266B2 - COMMUNICATION DEVICE AND SENSOR DEVICE EQUIPPED WITH THE SAME - Google Patents

Description

This disclosure relates to a communication device and a sensor device equipped with the same.

Conventionally, a sensor device equipped with a magnetic sensor and used in an electric power steering device is known (see, for example, Patent Document 1). The magnetic sensor has a sensor element and an output circuit, and the output circuit generates a SENT communication waveform according to the SENT protocol based on information including the magnetic flux density detected by the sensor element, and outputs it as an output signal. This SENT communication waveform generated according to the SENT protocol is composed of multiple pulse signals including various information, and includes, for example, a data signal including information on the detection value detected by the sensor element, as well as a status signal for determining the output signal.

For example, the status signal included in the SENT communication waveform generated by the output circuit described in Patent Document 1 includes information about an update counter whose value is incremented by +1 each time an output signal is transmitted. As a result, when the detection value included in the data signal does not change, the ECU receiving this output signal can determine whether a data fixation abnormality has occurred based on whether the value of the update counter has changed.

JP 2016-217870 A

In the SENT communication waveform generated according to the SENT protocol, the status signal is composed of a 4-bit data area. In addition, there are cases where it is desired to include information in the status signal other than the information for determining data fixation abnormalities, such as the product number of the sensor device or information for determining abnormalities in various internal components of the sensor device.

However, in the SENT protocol, the status signal is composed of 4 bits, and the amount of information that can be included in the status signal is limited. For this reason, if the 4-bit data area is used to transmit information for determining the model number of the sensor device or abnormalities in various internal components of the sensor device, it may not be possible to include information for determining data fixation abnormalities in the status signal. In this case, a communication device that outputs an output signal generated according to the SENT protocol may not be able to transmit information for determining data fixation abnormalities to the side receiving the output signal.

The present disclosure aims to provide a communication device that can transmit information for determining data fixation abnormalities without using the data area of a status signal.

The invention described in claim 1 is
A communication device that acquires a first detection value and a second detection value from a sensor (S1, S2) and outputs a signal according to the first detection value and the second detection value in a signal conforming to a SENT protocol,
a waveform generating unit (10) that generates a signal relating to the acquired first detection value and second detection value as a SENT communication waveform;
A signal output unit (20) that outputs a SENT communication waveform as an output signal,
The SENT communication waveform is configured with a plurality of predetermined data areas for the stored information,
The plurality of data areas include a first sensor area (R1) having a data length of 12 bits and storing information relating to a first detection value, and a second sensor area (R2) having a data length of 12 bits and storing information relating to a second detection value,
The waveform generator includes:
a sensor data creation unit (31, 32) that converts the first detection value into first sensor data, which is 12-bit data to be stored in a first sensor area, and converts the second detection value into second sensor data, which is 12-bit data to be stored in a second sensor area;
a data compression unit (41, 42) that compresses the amount of at least one of the first sensor data and the second sensor data to generate an empty area in which the first sensor data and the second sensor data are not stored in at least one of the first sensor area and the second sensor area;
and a discrimination information adding unit (50) that adds abnormality discrimination information to an empty area to determine whether or not a data fixation abnormality has occurred, the data fixation abnormality indicating a state in which the first sensor data and the second sensor data are not updated.

According to this, by adding the abnormality determination information to either the first sensor area or the second sensor area, the abnormality determination information can be transmitted without using the data area of the status signal.

The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below.

1 is a diagram for explaining a schematic configuration of a communication device according to a first embodiment. FIG. 13 is a diagram showing a SENT communication waveform for one frame. 10A to 10C are diagrams for explaining an operation of the discrimination information adding unit of the first embodiment when adding anomaly discrimination information to an empty area. FIG. 13 is a diagram illustrating a reference example in which sensor data is compressed using a Huffman code. FIG. 13 is a diagram illustrating an example of an appearance rate of sensor data acquired by a communication device; 13A and 13B are diagrams illustrating sensor data and an update counter included in an output signal when the communication device is in a normal state. 13A and 13B are diagrams illustrating sensor data and an update counter included in an output signal when the communication device is in an abnormal state. 13A and 13B are diagrams for explaining an operation of a discrimination information adding unit according to the second embodiment when adding anomaly discrimination information to an empty area. FIG. 13 is a diagram for explaining a schematic configuration of a communication device according to a third embodiment. 13A and 13B are diagrams for explaining an operation of a discrimination information adding unit according to the third embodiment when adding anomaly discrimination information to an empty area. 11A and 11B are diagrams illustrating a reference example in which sensor data is compressed by logarithmic compression; 11A and 11B are diagrams illustrating a reference example in which sensor data compressed by logarithmic compression is restored; FIG. 13 is a diagram for explaining a schematic configuration of a sensor device according to a fifth embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments may be given the same reference numerals, and their description may be omitted. In addition, in the embodiments where only some of the components are described, the components described in the preceding embodiments may be applied to the other parts of the components. The following embodiments may be partially combined with each other, as long as the combination does not cause any problems, even if not specifically stated.

First Embodiment
This embodiment will be described with reference to Figures 1 to 7. In this embodiment, for example, an example will be described in which the communication device 1 is used in a brake-by-wire system that controls the brakes of a vehicle. The brake-by-wire system is a brake system that includes a brake pedal (not shown) that is depressed by a driver, and controls the braking of wheels provided on the vehicle in accordance with the depression force applied when the driver depresses the brake pedal.

The brake-by-wire system, for example, includes two sensors S1 and S2 for detecting information related to the force applied when the brake pedal is depressed, and a control device E for controlling various components that control wheel braking according to the detection values detected by the two sensors S1 and S2. The communication device 1 of this embodiment is used to transmit the detection values detected by the two sensors S1 and S2 to the control device E. The control device E controls the various components provided in the brake-by-wire system based on the signals transmitted from the communication device 1.

The control device E is called an ECU (short for Electronic Control Unit). The communication device 1 transmits the detection values detected by the two sensors S1 and S2 to the control device E by transmitting signals corresponding to the detection values detected by the two sensors S1 and S2.

Hereinafter, of the two sensors S1 and S2, one sensor will be referred to as the first sensor S1, and the other sensor will be referred to as the second sensor S2. In addition, the detection value detected by the first sensor S1 will be referred to as the first detection value, and the detection value detected by the second sensor S2 will be referred to as the second detection value.

In this embodiment, the first sensor S1 and the second sensor S2 are provided at different positions on the brake pedal and are configured to be able to detect information about the depression force when the driver depresses the brake pedal independently of each other.

For example, the first sensor S1 is provided on a rotating shaft that rotatably supports the brake pedal, and is configured as a rotation angle sensor that detects the amount of rotation when the brake pedal is depressed by the driver. The first sensor S1 may also be configured as a magnetic sensor having a magnet and a Hall element, etc. In this case, the first sensor S1 detects the change in magnetism when the rotating shaft rotates, thereby detecting the force applied to the brake pedal according to the amount of rotation of the rotating shaft.

For example, the second sensor S2 is provided on the brake pedal and is configured as a stroke sensor that detects the amount of movement of the brake pedal when the driver presses it, thereby detecting the force of the driver's depression. The second sensor S2 may also be configured as an inductive sensor having a target metal and a coil section that detects the movement of the target metal. In this case, the second sensor S2 detects the change in impedance of the coil section when the brake pedal rotates, thereby detecting the force applied to the brake pedal according to the amount of movement of the brake pedal.

The first sensor S1 and the second sensor S2 have their respective output sides connected to the communication device 1, and transmit signals to the communication device 1 according to the detection values they detect.

The first sensor S1 and the second sensor S2 are not limited in their sensor configuration, and may be configured as a sensor other than a magnetic sensor and an inductive sensor, such as a pressure sensor that detects the pressure applied to the pedal when the driver presses the pedal.

The communication device 1 is a transmitting device that acquires a first detection value transmitted from the first sensor S1 and a second detection value transmitted from the second sensor S2, and outputs a signal corresponding to the acquired first detection value and second detection value to the control device E. The communication device 1 of this embodiment performs SENT communication with the control device E by outputting a digital signal that is generated according to the SENT protocol as a signal corresponding to the acquired first detection value and second detection value. Note that SENT is an abbreviation for Single Edge Nibble Transmission.

The communication device 1 is composed of a microcomputer including a memory unit such as a CPU, ROM, and RAM, and its peripheral circuits. The memory unit is composed of a non-transitive tangible storage medium. The communication device 1 performs various calculations and processes based on programs stored in the ROM. As shown in FIG. 1, the communication device 1 also includes a waveform generation unit 10 that generates a signal waveform based on signals input from the first sensor S1 and the second sensor S2, and a signal output unit 20 that outputs the signal waveform generated by the waveform generation unit 10 as an output signal.

The waveform generating unit 10 has a first sensor S1 and a second sensor S2 connected to its input side, and a signal output unit 20 connected to its output side. The waveform generating unit 10 generates a signal including information about the first detection value transmitted from the first sensor S1 and the second detection value transmitted from the second sensor S2 according to the SENT protocol, and transmits it to the signal output unit 20 as a SENT communication waveform P shown in FIG. 2.

Here, the SENT communication waveform P shown in FIG. 2 will be described. The SENT communication waveform P shown in FIG. 2 shows one frame of the communication waveform of the SENT communication waveform P generated by the waveform generating unit 10. As shown in FIG. 2, the SENT communication waveform P is composed of 10 pulse signals, and various information is stored in each of the 10 pulse signals. The information stored in the 10 pulse signals is predetermined based on the SENT protocol. The SENT communication waveform P expresses the content of the information stored in each pulse signal in the time between the falling edges of each pulse signal from the falling start timing to the next falling start timing. The information (i.e., data) stored in each pulse signal in the SENT communication waveform P is predetermined, and the SENT communication waveform P is composed of multiple data areas divided for each pulse signal.

Specifically, the SENT communication waveform P is composed of a synchronous calibration pulse Sy, a status communication nibble St, the first data nibble Da1 to the sixth data nibble Da6, a CRC nibble Cr, and a pause pulse Pa, which are connected in this order. The time between the falling edges of the synchronous calibration pulse Sy is predetermined. In contrast, the time between the falling edges of each pulse signal of the status communication nibble St, the first data nibble Da1 to the sixth data nibble Da6, the CRC nibble Cr, and the pause pulse Pa is variable.

The time between the falling edges of each of these nibbles and pause pulses Pa is set by the waveform generator 10 according to the data stored in each nibble and pause pulse Pa. In addition, each of the status communication nibble St, the first data nibble Da1 to the sixth data nibble Da6, and the CRC nibble Cr stores 4 bits of data per nibble.

In addition, in the SENT communication waveform P, the time between the falling edges of each pulse signal is expressed in tick units. The time of one tick can be set, for example, to 3 us (microseconds).

The synchronization/calibration pulse Sy is a pulse signal that is placed at the beginning of the SENT communication waveform P for each frame, and is a pulse signal for notifying the start timing of one frame of the SENT communication waveform P. The time between the falling edges of the synchronization calibration pulse Sy (i.e., the pulse width) is fixed at 56 ticks. When the control device E receives the SENT communication waveform P from the communication device 1, it can obtain the start timing of the SENT communication by detecting a pulse signal of a time that includes a predetermined tolerance in the 56 tick time.

The status and communication nibble St is a pulse signal placed next to the synchronous calibration pulse Sy. The status and communication nibble St is a pulse signal for notifying the control device E of the state of the communication device 1, the product number, and the like. The status and communication nibble St is configured to be able to store data with a data length of 4 bits, and stores, for example, data such as the normal or abnormal state of the components of the communication device 1, the product number, and the like, as data values from 0 to 15. The status and communication nibble St sets the time between falling edges to one of 15 stages from 12 ticks to 27 ticks depending on the contents of this data. As a result, the status communication nibble St expresses the normal or abnormal state of the components of the communication device 1, the product number, and the like, with 4 bits of data. The status communication nibble St in this embodiment corresponds to a status signal.

The first data nibble Da1 to the sixth data nibble Da6 are pulse signals placed after the status communication nibble St. Specifically, after the status communication nibble St, the first data nibble Da1, the second data nibble Da2, the third data nibble Da3, the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 are arranged in this order.

The first data nibble Da1 to the sixth data nibble Da6 are pulse signals for notifying the first detection value obtained from the first sensor S1 and the second detection value obtained from the second sensor S2. Each of the first data nibble Da1 to the sixth data nibble Da6 is configured to be able to store data with a data length of 4 bits. Each of the first data nibble Da1 to the sixth data nibble Da6 can store information about the first detection value obtained from the first sensor S1 or information about the second detection value obtained from the second sensor S2 as a data value from 0 to 15, for example.

In this embodiment, the first data nibble Da1, the second data nibble Da2, and the third data nibble Da3 store information about the first detection value transmitted from the first sensor S1. That is, the first detection value transmitted from the first sensor S1 is expressed by 12-bit data composed of the first data nibble Da1, the second data nibble Da2, and the third data nibble Da3. The first data nibble Da1, the second data nibble Da2, and the third data nibble Da3 can store the first detection value obtained from the first sensor S1 as a data value, for example, from 0 to 4095.

Specifically, the time between the falling edges of the first data nibble Da1, the second data nibble Da2, and the third data nibble Da3 is set to one of 15 stages ranging from 12 ticks to 27 ticks depending on the first detection value. As a result, the first data nibble Da1, the second data nibble Da2, and the third data nibble Da3 express the first detection value as 12-bit data. Hereinafter, in the SENT communication waveform P, the data area consisting of the first data nibble Da1, the second data nibble Da2, and the third data nibble Da3 and in which information related to the first detection value is stored is also referred to as the first sensor area R1. Moreover, the data stored in the first sensor area R1 and corresponding to the first detection value is also referred to as the first sensor data. The first sensor data is data corresponding to the first detection value acquired from the first sensor S1.

In addition, the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 store information about the second detection value transmitted from the second sensor S2. That is, the second detection value transmitted from the second sensor S2 is expressed by 12-bit data composed of the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6. The fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 can store the second detection value obtained from the second sensor S2 as a data value, for example, from 0 to 4095.

Specifically, the time between the falling edges of the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 is set to one of 15 stages ranging from 12 ticks to 27 ticks depending on the second detection value. As a result, the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 express the second detection value as 12-bit data. Hereinafter, in the SENT communication waveform P, the data area consisting of the fourth data nibble Da4, the fifth data nibble Da5, and the sixth data nibble Da6 and in which information related to the second detection value is stored is also referred to as the second sensor area R2. In addition, the data stored in the second sensor area R2 and corresponding to the second detection value is also referred to as the second sensor data. The second sensor data is data corresponding to the second detection value acquired from the second sensor S2.

The first sensor region R1 and the second sensor region R2 are adjacent to each other in the SENT communication waveform P. As a result, the first sensor data and the second sensor data are arranged consecutively among the 10 pulse signals that make up the SENT communication waveform P. Specifically, the second sensor data is stored next to the first sensor data among the various data stored in the SENT communication waveform P.

Here, in the first sensor region R1 and the second sensor region R2 of this embodiment, abnormality determination information for determining whether or not a data fixation abnormality has occurred in the first sensor data and the second sensor data contained in the output signal is added by the determination information adding unit 50 described later. The method of adding the abnormality determination information will be described later.

The CRC (Cyclic Redundancy Check) nibble Cr is a pulse signal placed next to the sixth data nibble Da6, and is a pulse signal for notifying the cyclic redundancy check value for the first data nibble Da1 to the sixth data nibble Da6. The CRC nibble Cr is configured to be able to store data with a data length of 4 bits, and stores the error detection/correction code values of the first data nibble Da1 to the sixth data nibble Da6 as data values of, for example, 0 to 15. The CRC nibble Cr sets the time between falling edges to one of 15 stages from 12 ticks to 27 ticks depending on the error detection/correction code values of the first data nibble Da1 to the sixth data nibble Da6. As a result, the CRC nibble Cr expresses the error detection/correction code values of the first data nibble Da1 to the sixth data nibble Da6 as 4-bit data.

The pause pulse Pa is a pulse signal placed next to the CRC nibble Cr, and is a pulse signal for keeping the length of one frame of the SENT communication waveform P constant. Meanwhile, the status communication nibble St, the first data nibble Da1 to the sixth data nibble Da6, and the CRC nibble Cr have their tick numbers set according to the data values they store, as described above. Then, the length of one frame of the SENT communication waveform P changes depending on the tick numbers of these nibbles. The pulse width of the pause pulse Pa is set in order to keep the changing length of one frame of the SENT communication waveform P at a predetermined tick number (e.g., 282 ticks).

Returning to FIG. 1, the waveform generating unit 10 is a signal waveform generating unit that generates a SENT communication waveform P consisting of the above-mentioned 10 pulse signals according to the SENT protocol each time the first detection value and the second detection value are acquired from the first sensor S1 and the second sensor S2. Furthermore, the waveform generating unit 10 of this embodiment is configured to be able to add information to the generated SENT communication waveform P for determining whether or not a data fixation abnormality has occurred in the first sensor data and the second sensor data contained in the output signal. The waveform generating unit 10 is configured to include a first sensor data creating unit 31, a second sensor data creating unit 32, a first data compressing unit 41, a second data compressing unit 42, and a determination information adding unit 50.

The first sensor data creation unit 31 generates first sensor data to be stored in the first sensor area R1, which is composed of the first data nibble Da1 to the third data nibble Da3, from among the various pulse signals that form the SENT communication waveform P. The first sensor data creation unit 31 has the first sensor S1 connected to its input side, and the first data compression unit 41 connected to its output side.

The first sensor data creation unit 31 is configured to include, for example, an analog-to-digital conversion circuit (i.e., an A/D conversion circuit). When the first sensor data creation unit 31 acquires a first detection value from the first sensor S1, it A/D converts the acquired first detection value to generate 12-bit first sensor data for storage in the first sensor region R1. The first sensor data creation unit 31 transmits the generated first sensor data to the first data compression unit 41.

The second sensor data creation unit 32 generates second sensor data to be stored in the second sensor area R2, which is composed of the fourth data nibble Da4 to the sixth data nibble Da6, among the various pulse signals that form the SENT communication waveform P. The second sensor data creation unit 32 is configured to include, for example, an analog-to-digital conversion circuit (i.e., an A/D conversion circuit). When the second sensor data creation unit 32 acquires a second detection value from the second sensor S2, it A/D converts the acquired second detection value to generate 12-bit second sensor data to store in the second sensor area R2. The second sensor data creation unit 32 transmits the generated second sensor data to the second data compression unit 42.

The first data compression unit 41 compresses the amount of data of the first sensor data generated by the first sensor data creation unit 31 to generate an empty area in the 12-bit first sensor area R1 that does not contain either the first sensor data or the second sensor data. The first data compression unit 41 is configured to include a compression circuit that compresses digital signals. The first data compression unit 41 compresses the amount of data of the first sensor data generated by the first sensor data creation unit 31, and stores the compressed first sensor data in the first sensor area R1.

The second data compression unit 42 compresses the amount of data of the second sensor data generated by the second sensor data creation unit 32 to generate an empty area in the 12-bit second sensor area R2 that does not contain either the first sensor data or the second sensor data. The second data compression unit 42 is configured to include a compression circuit that compresses digital signals. The second data compression unit 42 compresses the amount of data of the second sensor data generated by the second sensor data creation unit 32, and stores the compressed second sensor data in the second sensor area R2.

Hereinafter, the compressed first sensor data will also be referred to as compressed first sensor data, and the compressed second sensor data will also be referred to as compressed second sensor data.

The discrimination information adding unit 50 adds abnormality discrimination information, which is data for determining whether or not a data fixation abnormality has occurred, to the empty space generated by the first data compression unit 41 and the second data compression unit 42. The discrimination information adding unit 50 is configured as an update counter whose counter value increases by one each time an output signal is transmitted as the abnormality discrimination information.

The signal output unit 20 transmits the SENT communication waveform P generated by the waveform generation unit 10 to a control device E arranged outside the communication device 1. The signal output unit 20 transmits the SENT communication waveform P, which is generated each time the communication device 1 acquires the first detection value and the second detection value from the first sensor S1 and the second sensor S2, as an output signal to the control device E. The SENT communication waveform P transmitted by the signal output unit 20 includes anomaly determination information in addition to compressed first sensor data and compressed second sensor data in the first sensor region R1 and the second sensor region R2.

Next, the operation of the communication device 1 will be described. When the communication device 1 acquires the first detection value and the second detection value from the first sensor S1 and the second sensor S2, the waveform generating unit 10 generates the SENT communication waveform P.

Specifically, when the first sensor data creation unit 31 acquires the first detection value from the first sensor S1, it A/D converts the first detection value to generate 12-bit first sensor data. Then, the first sensor data creation unit 31 transmits the generated first sensor data to the first data compression unit 41.

The first data compression unit 41 receives the first sensor data from the first sensor data creation unit 31. Then, as shown in FIG. 3, the first data compression unit 41 compresses the data amount of the first sensor data, stores the compressed first sensor data in the first sensor area R1, and generates an empty area in the first sensor area R1. Here, the first data compression unit 41 compresses the 12-bit first sensor data by 2 bits to create compressed first sensor data with a data length of 10 bits, thereby generating an empty area of 2 bits. Specifically, the first data compression unit 41 stores the compressed first sensor data on the side of the first sensor area R1 that is connected to the status communication nibble St, and generates an empty area of 2 bits on the side of the first sensor area R1 that is connected to the second sensor data.

The first data compression unit 41 of this embodiment also compresses the amount of data of the first sensor data using a lossless compression method so that the control device E, which receives an output signal including the compressed first sensor data, can restore the first sensor data to the state before compression. Specifically, the first data compression unit 41 compresses the 12-bit first sensor data to 10 bits using Huffman coding, which is a lossless compression method. Therefore, the first sensor data compressed using Huffman coding does not suffer from data loss due to compression, and can be restored to the first sensor data before compression.

When the second sensor data creation unit 32 acquires the second detection value from the second sensor S2, it A/D converts the second detection value to generate 12-bit second sensor data. Then, the second sensor data creation unit 32 transmits the generated second sensor data to the second data compression unit 42.

The second data compression unit 42 receives the second sensor data from the second sensor data creation unit 32. Then, as shown in FIG. 3, the second data compression unit 42 compresses the amount of data of the second sensor data, stores the compressed second sensor data in the second sensor area R2, and generates an empty area in the second sensor area R2. Here, the second data compression unit 42 compresses the 12-bit second sensor data by 2 bits to produce compressed second sensor data with a data length of 10 bits, thereby generating an empty area of 2 bits. Specifically, the second data compression unit 42 stores the compressed second sensor data in the side of the second sensor area R2 that is connected to the CRC nibble Cr, and generates an empty area of 2 bits in the side of the second sensor area R2 that is connected to the first sensor data.

In addition, the second data compression unit 42 of this embodiment compresses the amount of data of the second sensor data by a lossless compression method so that the control device E, which receives an output signal including the compressed second sensor data, can restore the second sensor data to the state before compression. Specifically, the second data compression unit 42 compresses the 12-bit second sensor data to 10 bits by Huffman coding, which is a lossless compression method. Therefore, the second sensor data compressed by Huffman coding does not suffer from data loss due to compression, and can be restored to the second sensor data before compression.

Here, a compression method using Huffman coding will be described with reference to the reference examples shown in Figs. 4 and 5. When compressing data, Huffman coding reduces the overall amount of data by assigning shorter bit numbers to data with a higher occurrence rate and longer bit numbers to data with a lower occurrence rate.

In the reference example shown in Figure 4, we explain an example of compressing 12 characters of data consisting of five types of characters, "A", "B", "C", "D", and "E", using Huffman coding.

Here, in the 12-character data before compression, each of the five types of characters is represented by a fixed-length 3-bit code. Specifically, the character "A" is represented by the code "000", the character "B" is represented by the code "001", the character "C" is represented by the code "010", the character "D" is represented by the code "011", and the character "E" is represented by the code "100".

For example, when expressing 12-character data such as "DAEBCBACBBBC" using these 3-bit codes, the 12-character data becomes "011 000 100 001 010 001 000 010 001 001 001 010". When expressing 12-character data such as "DAEBCBACBBBC" using a 3-bit fixed-length code, the data length becomes 36 bits, which is 3 bits multiplied by the number of characters in the 12 characters. Here we explain Huffman coding, which compresses such 36-bit data by changing the number of bits assigned depending on the occurrence rate of the characters.

The occurrence rate of each letter in the 12-letter "DAEBCBACBBBC" is as follows: "B" 5 times, "C" 3 times, "A" 2 times, "D" and "E" 1 time each. Therefore, the occurrence rate of each letter is "B", "C", "A", "D" or "E" in descending order.

For this reason, when compressing using Huffman coding, of the five characters "A," "B," "C," "D," and "E," characters with a higher occurrence rate are assigned codes with shorter bit numbers, and data with a lower occurrence rate are assigned codes with longer bit numbers. For example, the character "B" with the highest occurrence rate is represented by the code "0," and the character "C" with the second highest occurrence rate is represented by the code "10." The character "A" with the third highest occurrence rate is represented by the code "110," the character "D" with the lowest occurrence rate is represented by the code "1120," and the other character "E" with the lowest occurrence rate is represented by the code "1111."

Then, after compression, the 12-character data "DAEBCBACBBBC" can be expressed as "1110 110 1111 0 10 0 110 10 0 0 0 10". And after compression, the data length of the 12-character data "DAEBCBACBBBC" will be 25 bits. Therefore, when compressing using Huffman coding, the 12-character data "DAEBCBACBBBC" can be compressed from 36 bits to 25 bits.

The Huffman tree shown in Figure 4 shows the correspondence between the number of occurrences of characters and the assigned codes in data of 12 characters consisting of five types of characters: "A", "B", "C", "D", and "E".

The first data compression unit 41 compresses the 12-bit first sensor data generated by the first sensor data creation unit 31 by 2 bits using a Huffman code, thereby generating a 2-bit empty space on the side of the first sensor region R1 that is adjacent to the second sensor data. The second data compression unit 42 compresses the 12-bit second sensor data generated by the second sensor data creation unit 32 by 2 bits using a Huffman code, thereby generating a 2-bit empty space on the side of the second sensor region R2 that is adjacent to the first sensor data. As a result, a 4-bit empty space is generated in the SENT communication waveform P.

In this embodiment, the first sensor S1 and the second sensor S2 detect the force applied when the driver presses the brake pedal. The brake pedal that controls the vehicle is often pressed with a relatively weak force, and in contrast, it is rarely pressed with a relatively strong force. For example, it is expected that the brake pedal will be pressed with the greatest force when the vehicle is brought to an abrupt halt. However, there are few opportunities for such a vehicle to be brought to an abrupt halt.

In such a case, the first sensor S1 and the second sensor S2 provided on the brake pedal to detect the driver's pressing force are more likely to detect a relatively weak pressing force, and are less likely to detect a relatively strong pressing force.

Here, when converting the first detection value acquired from the first sensor S1 into the first sensor data, the first detection value is expressed as a 12-bit data value ranging from 0 to 4095, and the greater the pedal force of the driver, the greater the data value. In such a case, as shown in FIG. 5, the smaller the data value of the first sensor data, the more likely it is to appear, and the greater the value, the less likely it is to appear.

When the method of expression used to convert the second detection value obtained from the second sensor S2 into the second sensor data is the same as the method of expression used to convert the first detection value into the first sensor data, the smaller the data value of the second sensor data, the more likely it is to appear, and the larger the value, the less likely it is to appear.

In such a case, when compressing using Huffman codes, the first data compression unit 41 and the second data compression unit 42 assign a shorter number of bits to the smaller data values of the first sensor data and the second sensor data. In contrast, when compressing using Huffman codes, the first data compression unit 41 and the second data compression unit 42 assign a longer number of bits to the larger data values of the first sensor data and the second sensor data.

Then, the discrimination information adding unit 50 adds the abnormality discrimination information composed of an update counter to the empty area generated by the first data compression unit 41 and the second data compression unit 42. Specifically, the discrimination information adding unit 50 of this embodiment adds the abnormality discrimination information composed of an update counter expressed by a data value from 0 to 15, for example, to the 4-bit empty area generated by the first data compression unit 41 and the second data compression unit 42. As a result, the abnormality discrimination information is added to the first sensor area R1 and the second sensor area R2 of the SENT communication waveform P generated by the waveform generating unit 10.

The value of the update counter, which is expressed as a data value from 0 to 15, is incremented by 1 each time an output signal is transmitted. Specifically, the update counter value is updated in the following order each time an output signal is transmitted: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. Then, when an output signal is transmitted after an output signal with the update counter value reaching its maximum value of 15 has been transmitted, the update counter value returns to its minimum value of 0.

Then, the signal output unit 20 transmits the SENT communication waveform P generated by the waveform generation unit 10 to the control device E each time the communication device 1 acquires the first detection value and the second detection value from the first sensor S1 and the second sensor S2. Specifically, the signal output unit 20 transmits the SENT communication waveform P, which includes the compressed first sensor data, the compressed second sensor data, and the abnormality determination information composed of the update counter, as an output signal to the control device E.

When the control device E receives an output signal from the communication device 1, it acquires various information contained in the SENT communication waveform P. The control device E then restores the compressed first sensor data stored in the first sensor area R1 and compressed with Huffman code, and restores the compressed second sensor data stored in the second sensor area R2 and compressed with Huffman code. Here, the compressed first sensor data and the compressed second sensor data are compressed with Huffman code, which is a lossless compression method. Therefore, by restoring the compressed first sensor data and the compressed second sensor data, the control device E can return the first sensor data and the second sensor data to their pre-compression state without data loss.

The control device E also determines whether or not a data fixation abnormality has occurred based on the abnormality determination information stored in the first sensor area R1 and the second sensor area R2. For example, the control device E determines whether or not a data fixation abnormality has occurred based on whether or not the update counter value included in the currently received SENT communication waveform P differs from the update counter value included in the previously received SENT communication waveform P.

A state in which a data fixation abnormality has occurred will be described with reference to Figures 6 and 7. If the force applied to the brake pedal is constant when the control device E receives an output signal, the first sensor S1 and the second sensor S2 repeatedly transmit the same detection value to the communication device 1. In this case, the communication device 1 repeatedly transmits an output signal including first sensor data having the same data value to the control device E, and also repeatedly transmits an output signal including second sensor data having the same data value to the control device E. Then, as shown in Figure 6, the control device E repeatedly obtains the same data value of the first sensor data from the communication device 1, and also repeatedly obtains the same data value of the second sensor data.

When the same data value of the first sensor data and the same data value of the second sensor data are repeatedly acquired, there is a risk that the output signal received this time is the same as the output signal received last time. In other words, if the communication device 1 goes into an abnormal state, the first sensor data and the second sensor data included in the output signal output by the communication device 1 may not be updated, and these data may become fixed.

However, if the value of the update counter included in the currently received output signal is different from the value of the update counter included in the previously received output signal, the control device E can determine that the currently received output signal is different from the previously received output signal. In other words, even if the sensor data included in the currently received output signal is the same as the sensor data included in the previously received output signal, the control device E can determine that a data fixation anomaly has not occurred, since the received output signal is different from the previously received output signal. For this reason, the control device E can determine that the communication device 1 is in a normal state, even if the control device E repeatedly acquires the same data value of the first sensor data and the same data value of the second sensor data.

In contrast, as shown in FIG. 7, if the value of the update counter included in the currently received output signal is the same as the value of the update counter included in the previously received output signal, the control device E can determine that the currently received output signal is the same as the previously received output signal. In other words, the control device E can determine that a data fixation abnormality has occurred, assuming that the currently received output signal is the same as the previously received output signal. Therefore, the control device E repeatedly acquires the same data value of the first sensor data and the same data value of the second sensor data, and can determine that the communication device 1 is in an abnormal state when the value of the update counter is not updated.

As described above, the communication device 1 of this embodiment includes a waveform generating unit 10 that generates a signal including the first detection value and the second detection value acquired from the first sensor S1 and the second sensor S2 as a SENT communication waveform P. The first sensor data creating unit 31 converts the first detection value into 12-bit first sensor data for storage in the first sensor area R1. The second sensor data creating unit 32 converts the second detection value into 12-bit second sensor data for storage in the second sensor area R2. The first data compressing unit 41 compresses the amount of data of the first sensor data to generate an empty area in the first sensor area R1. The second data compressing unit 42 compresses the amount of data of the second sensor data to generate an empty area in the second sensor area R2. The discrimination information adding unit 50 adds abnormality discrimination information for determining whether or not a data fixation abnormality has occurred to the empty area.

By adding abnormality determination information to the first sensor area R1 and the second sensor area R2, the abnormality determination information can be transmitted to the control device E without using the data area of the status communication nibble St.

Furthermore, the above embodiment provides the following advantages:

(1) In the above embodiment, the first data compression unit 41 compresses the amount of data of the first sensor data to generate an empty area in the first sensor area R1. The second data compression unit 42 compresses the amount of data of the second sensor data to generate an empty area in the second sensor area R2.

This makes it easier to increase the data length of the free space by compressing both the first sensor data and the second sensor data.

(2) In the above embodiment, the first data compression unit 41 compresses the first sensor data to generate a 2-bit empty area on the side of the first sensor region R1 that is adjacent to the second sensor data. The second data compression unit 42 compresses the amount of data of the second sensor data to generate a 2-bit empty area on the side of the second sensor region R2 that is adjacent to the first sensor data. The discrimination information adding unit 50 then adds anomaly discrimination information with a data length of 4 bits to the empty area formed across the first sensor region R1 and the second sensor region R2.

However, when the control device E that receives the output signal receives the output signal output from the communication device 1, the control device E that receives the output signal may miss the output signal. In such a case, if the abnormality determination information is composed of a data length of 1 or 2 bits, it is difficult for the control device E that receives the output signal to determine that there is an abnormality. For example, if the abnormality determination information is composed of a 1-bit update counter and the control device E misses receiving one output signal transmitted from the communication device 1, the control device E will continuously receive output signals that contain the same update counter value included in the output signal it receives. In such a case, there is a risk that the control device E will determine that a data fixation abnormality has occurred even though a data fixation abnormality has not occurred.

In contrast, according to this embodiment, the abnormality determination information is configured with a data length of 4 bits, so even if the control device E misses an output signal output from the communication device 1, it is difficult to continuously receive output signals with the same update counter value. This makes it difficult to erroneously determine a data fixation abnormality.

The first data compression unit 41 and the second data compression unit 42 also form a single 4-bit empty area across two empty areas obtained by compressing the first sensor data and the second sensor data, respectively. Therefore, compared to forming a 4-bit empty area in either the first sensor area R1 or the second sensor area R2, the amount of compression of the sensor data to be compressed can be reduced compared to compressing only either the first sensor data or the second sensor data by 4 bits.

(3) In the above embodiment, the abnormality determination information is composed of an update counter whose counter value changes each time an output signal is transmitted.

This allows the abnormality determination information to be added in a simple manner. Furthermore, when receiving an output signal, the control device E can easily determine whether or not a data fixation abnormality has occurred.

(4) In the above embodiment, the first data compression unit 41 compresses the amount of data of the first sensor data using a lossless compression method. Also, the second data compression unit 42 compresses the amount of data of the second sensor data using a lossless compression method.

As a result, when the control device E restores the compressed first sensor data and the compressed second sensor data, it is possible to restore the first sensor data and the second sensor data to their pre-compression states without data loss. This makes it possible to improve the detection accuracy of the first sensor S1 and the second sensor S2 compared to when the first data compression unit 41 and the second data compression unit 42 compress the amount of data of the first sensor data and the second sensor data, respectively, using a lossy compression method.

(5) In the above embodiment, the first data compression unit 41 compresses the amount of data of the first sensor data by using Huffman codes. The second data compression unit 42 compresses the amount of data of the second sensor data by using Huffman codes.

This allows compressed data to be created according to the first detection value acquired from the first sensor S1 and the second detection value acquired from the second sensor S2, whichever detection value has a different occurrence rate. Therefore, for example, if there is a bias in the occurrence rate of the first detection value acquired from the first sensor S1, the sensor data can be compressed according to the bias in the occurrence rate.

For example, when there is a bias in the occurrence rate, such as the first detection value and the second detection value indicating the brake pedal force obtained from the first sensor S1 and the second sensor S2 in this embodiment, the first sensor data and the second sensor data can be compressed according to the occurrence rate.

In such a case, the first data compression unit 41 and the second data compression unit 42 can compress the first sensor data and the second sensor data by assigning a shorter number of bits to the first sensor data and the second sensor data with a higher occurrence rate, and assigning a longer number of bits to the first sensor data and the second sensor data with a lower occurrence rate.

(Modification of the first embodiment)
In the above-described first embodiment, an example has been described in which the first data compression unit 41 compresses the amount of data of the first sensor data by using Huffman codes, and the second data compression unit 42 compresses the amount of data of the second sensor data by using Huffman codes, but the present invention is not limited to this. If the compression method is a lossless compression method, the first data compression unit 41 may be configured to compress the amount of data of the first sensor data by using a compression method different from the Huffman codes. Also, if the compression method is a lossless compression method, the second data compression unit 42 may be configured to compress the amount of data of the second sensor data by using a compression method different from the Huffman codes.

Second Embodiment
Next, the second embodiment will be described with reference to FIG. 8. In this embodiment, the amount of first sensor data compressed by the first data compression unit 41 and the position where the empty area is formed are different from those in the first embodiment. Also, in this embodiment, the amount of second sensor data compressed by the second data compression unit 42 and the position where the empty area is formed are different from those in the first embodiment. Other than these, the second embodiment is similar to the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and the description of the same parts as the first embodiment may be omitted.

The first data compression unit 41 of this embodiment receives the first sensor data from the first sensor data creation unit 31. Then, as shown in FIG. 8, the first data compression unit 41 compresses the data amount of the first sensor data, stores the compressed first sensor data in the first sensor area R1, and creates an empty area in the first sensor area R1.

Specifically, the first data compression unit 41 compresses the 12-bit first sensor data by 4 bits to generate compressed first sensor data with a data length of 8 bits, thereby generating a 4-bit empty space in the first sensor area R1. In addition, the first data compression unit 41 stores the 8-bit compressed first sensor data on the side of the first sensor area R1 that is connected to the second sensor data, and generates a 4-bit empty space on the side of the first sensor area R1 that is connected to the status communication nibble St.

The second data compression unit 42 also receives the second sensor data from the second sensor data creation unit 32. Then, as shown in FIG. 8, the second data compression unit 42 compresses the amount of data of the second sensor data, stores the compressed second sensor data in the second sensor area R2, and creates an empty area in the second sensor area R2.

Specifically, the second data compression unit 42 compresses the 12-bit second sensor data by 4 bits to generate compressed second sensor data with a data length of 8 bits, thereby generating a 4-bit empty area in the second sensor area R2. In addition, the second data compression unit 42 stores the compressed second sensor data on the side of the second sensor area R2 adjacent to the first sensor data, and generates a 4-bit empty area on the side of the second sensor area R2 adjacent to the CRC nibble Cr.

In this way, the first data compression unit 41 of this embodiment generates a 4-bit empty area in the first sensor region R1, and the second data compression unit 42 generates a 4-bit empty area in the second sensor region R2, so that two 4-bit empty areas are generated in the SENT communication waveform P.

Then, the discrimination information adding unit 50 adds anomaly discrimination information with a data length of 4 bits to each of the two 4-bit empty areas.

According to this, for example, if the abnormality determination information added to the first sensor region R1 and the abnormality determination information added to the second sensor region R2 are the same information, the occurrence of a sticking abnormality can be easily determined by comparing the two abnormality determination information included in the output signal. Also, for example, if the abnormality determination information added to the first sensor region R1 and the abnormality determination information added to the second sensor region R2 are different information, it becomes less likely that an abnormal state will occur in which the two abnormality determination information simultaneously do not function correctly due to an external factor.

Third Embodiment
Next, a third embodiment will be described with reference to Figures 9 and 10. In this embodiment, the communication device 1 does not include the first data compression unit 41, and the amount of second sensor data compressed by the second data compression unit 42 and the position where the empty area is formed are different from those in the first embodiment. Other than these, the third embodiment is similar to the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and the description of the same parts as the first embodiment may be omitted.

As shown in FIG. 9, the communication device 1 of this embodiment does not include a first data compression unit 41. Therefore, when the first sensor data creation unit 31 acquires the first detection value from the first sensor S1, it A/D converts the first detection value to generate 12-bit first sensor data. Then, as shown in FIG. 10, the first sensor data creation unit 31 stores the generated 12-bit first sensor data in the first sensor area R1. Therefore, in the SENT communication waveform P generated by the waveform generation unit 10 of this embodiment, no empty area is formed in the first sensor area R1, and no abnormality determination information is added.

The second data compression unit 42 also receives the second sensor data from the second sensor data creation unit 32. Then, as shown in FIG. 10, the second data compression unit 42 compresses the amount of data of the second sensor data, stores the compressed second sensor data in the second sensor area R2, and creates an empty area in the second sensor area R2.

Specifically, the second data compression unit 42 compresses the 12-bit second sensor data by 4 bits to generate compressed second sensor data with a data length of 8 bits, thereby generating a 4-bit empty space in the second sensor area R2. Specifically, the second data compression unit 42 stores the compressed second sensor data on the side of the second sensor area R2 adjacent to the first sensor data, and generates a 4-bit empty space on the side of the second sensor area R2 adjacent to the CRC nibble Cr.

Then, the discrimination information adding unit 50 adds the abnormality discrimination information with a data length of 4 bits to the 4-bit empty area of the second sensor area R2.

In this manner, in this embodiment, of the first sensor data and the second sensor data, only the second sensor data is compressed in data volume. Then, of the first sensor region R1 and the second sensor region R2, the second data compression unit 42 generates an empty area only in the second sensor region R2.

However, when compressing the amount of various data using a compression circuit or the like, a portion of the data may be lost due to compression. For this reason, for example, when compressing the amount of second sensor data using the second data compression unit 42, a portion of the second sensor data may be lost. If a portion of the second sensor data is lost due to compression, when the control device E restores the compressed second sensor data, it is not possible to restore the data to data that completely matches the second sensor data before compression. This is undesirable because it affects the detection accuracy of the second detection value acquired by the control device E by transmitting the detection value detected by the second sensor S2 to the control device E.

In contrast, according to this embodiment, only the second sensor data of the first and second sensor data is compressed, so that it is possible to avoid partial loss of the uncompressed first sensor data due to compression. This allows the detection value of the first sensor S1 to be transmitted to the control device E with high accuracy, thereby improving the detection accuracy of the first detection value acquired by the control device E. In particular, when the first sensor S1 and the second sensor S2 are configured to detect the amount of displacement of different objects, etc., and one sensor can obtain a detection value with higher accuracy than the other sensor, a method of compressing only the other sensor data, as in this embodiment, is effective.

Furthermore, the above embodiment provides the following advantages:

(1) In the above embodiment, the second data compression unit 42 generates a 4-bit free space by compressing the amount of data of the second sensor data by 4 bits or more. In addition, the discrimination information adding unit 50 adds anomaly discrimination information with a data length of 4 bits to the free space.

As a result, even if the control device E misses an output signal output from the communication device 1, it becomes difficult to continuously receive output signals with the same update counter value. This makes it difficult to erroneously identify a data fixation anomaly.

(Modification of the third embodiment)
In the above-described third embodiment, an example has been described in which the communication device 1 does not include the first data compression unit 41, and the second data compression unit 42 compresses only the amount of second sensor data among the first sensor data and the second sensor data, but the present invention is not limited to this. For example, the communication device 1 may be configured not to include the second data compression unit 42, but to include the first data compression unit 41, and the first data compression unit 41 may compress only the amount of first sensor data among the first sensor data and the second sensor data.

Fourth Embodiment
Next, a fourth embodiment will be described with reference to Fig. 11 and Fig. 12. This embodiment differs from the first embodiment in that the first data compression unit 41 compresses the first sensor data by a lossy compression method and the second data compression unit 42 compresses the second sensor data by a lossy compression method. The rest is the same as the first embodiment. Therefore, in this embodiment, the parts different from the first embodiment will be mainly described, and the description of the parts similar to the first embodiment may be omitted.

When the first data compression unit 41 of this embodiment receives the first sensor data from the first sensor data creation unit 31, it compresses the amount of data of the first sensor data by a lossy compression method. Specifically, the first data compression unit 41 compresses the 12-bit first sensor data to 10 bits by logarithmic compression.

In addition, when the second data compression unit 42 of this embodiment receives the second sensor data from the second sensor data creation unit 32, it compresses the amount of data of the second sensor data by a lossy compression method. Specifically, the second data compression unit 42 compresses the 12-bit second sensor data to 10 bits by logarithmic compression.

Here, a compression method when compressing by logarithmic compression will be described with reference to the reference examples shown in Figs. 11 and 12. In logarithmic compression, the correspondence between the data values before compression and the data values after compression is predetermined, and the data values before compression are converted based on this predetermined correspondence, thereby reducing the overall data volume. The correspondence between the data values before compression and the data values after compression is determined logarithmically, so that the smaller the data value before compression, the lower the resolution of the data value after compression, and conversely, the larger the data value before compression, the higher the resolution of the data value after compression.

Here, when converting the first detection value acquired from the first sensor S1 into the first sensor data, the first detection value is expressed as a 12-bit data value from 0 to 4095, and the greater the pedal force of the driver, the greater the data value. A case will be described in which the uncompressed first sensor data expressed as a 12-bit data value from 0 to 4095 is compressed into an 8-bit data value from 0 to 255 by logarithmic compression. In this case, as shown in FIG. 11, the correspondence between the data value of the first sensor data before compression and the data value of the first sensor data after compression is predetermined so that the closer the uncompressed first sensor data is to 0, the lower the resolution of the compressed data value. In contrast, the correspondence between the data value of the first sensor data before compression and the data value of the first sensor data after compression is predetermined so that the closer the uncompressed first sensor data is to 4095, the higher the resolution of the compressed data value.

Specifically, the correspondence between the data value of the first sensor data before compression and the data value of the first sensor data after compression is determined so that a single predetermined value is assigned to any data value within a predetermined range of the data value before compression. The predetermined range of the data value of the first sensor data before compression is determined to be narrower as the data value of the first sensor data before compression is closer to 0.

Therefore, when the first data compression unit 41 compresses the first sensor data, the smaller the first detection value obtained from the first sensor S1, the more the amount of data loss due to logarithmic compression can be suppressed.

When the control device E receives an output signal from the communication device 1, it restores the compressed first sensor data stored in the first sensor area R1 and compressed by logarithmic compression, and restores the compressed second sensor data stored in the second sensor area R2 and compressed by logarithmic compression. Here, the compressed first sensor data and the compressed second sensor data are compressed by logarithmic compression, which is a lossy compression method.

For this reason, when the control device E restores the compressed first sensor data and the compressed second sensor data, it converts the 8-bit compressed data values of 0 to 255 into 12-bit data values of 0 to 4095, as shown in FIG. 12. In this case, the correspondence between the data values of the first sensor data before restoration and the data values of the first sensor data after restoration is predetermined so that the closer the first sensor data before restoration is to 0, the higher the resolution of the restored data value. In contrast, the correspondence between the data values of the first sensor data before restoration and the data values of the first sensor data after restoration is predetermined logarithmically so that the closer the first sensor data before restoration is to 255, the lower the resolution of the restored data value.

Specifically, the correspondence between the data value of the first sensor data before restoration and the data value of the first sensor data after restoration is determined so that a data value after restoration is assigned a single predetermined value to any data value within a predetermined range of data values before restoration. The predetermined range of the data values of the first sensor data before restoration is determined to be wider the closer the first sensor data before restoration is to 0.

In this manner, in this embodiment, the first data compression unit 41 compresses the amount of data of the first sensor data using a lossy compression method. Also, the second data compression unit 42 compresses the amount of data of the second sensor data using a lossy compression method.

This makes it easier to reduce the amount of data of each of the first sensor data and second sensor data after compression compared to when the amount of data of each of the first sensor data and second sensor data is compressed using a lossless compression method.

Furthermore, the above embodiment provides the following advantages:

(1) In the above embodiment, the first data compression unit 41 compresses the amount of data of the first sensor data by logarithmic compression. Also, the second data compression unit 42 compresses the amount of data of the second sensor data by logarithmic compression.

When the first sensor data and the second sensor data are logarithmically compressed, the smaller the detection values input from the first sensor S1 and the second sensor S2, the lower the resolution at which the first sensor data and the second sensor data are compressed. In contrast, the larger the detection values input from the first sensor S1 and the second sensor S2, the higher the resolution at which the first sensor data and the second sensor data are compressed. Therefore, when the control device E restores the compressed first sensor data and the second sensor data, the larger the detection values, the more accurately the first sensor data and the second sensor data can be restored.

When the first sensor S1 and the second sensor S2 connected to the communication device 1 detect the pedal force applied to the brake pedal, it may be required to detect the pedal force applied when the pedal is depressed with a relatively large force more accurately than when the pedal is depressed with a small force. For this reason, when the first sensor data and the second sensor data are compressed by the first data compression unit 41 and the second data compression unit 42, it is desirable to compress the first sensor data and the second sensor data so that the pedal force applied when the pedal is depressed with a relatively large force can be accurately restored.

According to this embodiment, the first data compression unit 41 and the second data compression unit 42 compress the first sensor data and the second sensor data acquired when a relatively large force is applied logarithmically, thereby compressing the sensor data with high resolution. Therefore, the control device E can accurately acquire the stepping force when a relatively large force is applied, which is desirably detected with high accuracy.

(Modification of the fourth embodiment)
In the above-described fourth embodiment, an example has been described in which the first data compression unit 41 compresses the amount of data of the first sensor data by logarithmic compression, and the second data compression unit 42 compresses the amount of data of the second sensor data by logarithmic compression, but the present invention is not limited to this. If the compression method is a lossy compression method, the first data compression unit 41 may be configured to compress the amount of data of the first sensor data by a compression method different from logarithmic compression. Also, if the compression method is a lossy compression method, the second data compression unit 42 may be configured to compress the amount of data of the second sensor data by a compression method different from logarithmic compression.

Fifth Embodiment
Next, a fifth embodiment will be described with reference to Fig. 13. This embodiment differs from the first embodiment in that the communication device 1 is provided in the sensor device SD. The rest of the fifth embodiment is the same as the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and the description of the same parts as the first embodiment may be omitted.

The communication device 1 of this embodiment is provided in a sensor device SD, as shown in FIG. 13. The sensor device SD includes a first sensor element 61 and a second sensor element 62 that detect the force applied when the driver depresses the brake pedal, which is the detection target. The first sensor element 61 corresponds to the first sensor S1 described in the first embodiment. The second sensor element 62 corresponds to the second sensor S2 described in the first embodiment.

The first sensor element 61 is connected to the first sensor data creation unit 31. The first sensor element 61 detects the force applied when the driver presses the brake pedal, and transmits a signal corresponding to the detected force to the first sensor data creation unit 31. The second sensor element 62 is connected to the second sensor data creation unit 32. The second sensor element 62 detects the force applied when the driver presses the brake pedal, and transmits a signal corresponding to the detected force to the second sensor data creation unit 32.

By configuring the communication device 1 to be provided in the sensor device SD, it is easier to install the communication device 1 and the sensor device SD compared to when the communication device 1 and the sensor device SD are configured separately.

Other Embodiments
Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as described below.

In the above embodiment, the first sensor S1 and the second sensor S2 are configured independently of each other, and the first detection value detected by the first sensor S1 and the second detection value detected by the second sensor S2 are input to the communication device 1, but the present invention is not limited to this.

For example, the first sensor S1 and the second sensor S2 may each detect the same object, and the first sensor S1 and the second sensor S2 may each transmit the detection values detected from the same detection object to the communication device 1.

In the above embodiment, the first sensor S1 and the second sensor S2 are provided on the brake pedal, and a signal corresponding to the force applied by the driver when depressing the brake pedal is output to the communication device 1, but this is not limited to the above example.

For example, the first sensor S1 and the second sensor S2 may be provided on different detection objects, and the detection values detected from the different detection objects may be transmitted to the communication device 1.

In the above embodiment, an example was described in which the free space generated by the first data compression unit 41 and the second data compression unit 42 is 4 bits, and the abnormality determination information is composed of a data length of 4 bits, but this is not limited to this.

For example, the free space generated by the first data compression unit 41 and the second data compression unit 42 may have a data length of less than 4 bits (e.g., 3 bits) or may have a data length of more than 4 bits (e.g., 5 bits). If the free space has a data length of less than 4 bits, the abnormality determination information may be configured with a data length of less than 4 bits. If the free space has a data length of more than 4 bits, the abnormality determination information may be configured with a data length of more than 4 bits.

In the above embodiment, an example was described in which the abnormality determination information is configured as an update counter whose counter value increases by one each time an output signal is transmitted, but the present invention is not limited to this.

For example, the abnormality determination information may be configured as an update counter whose counter value decreases by one each time an output signal is transmitted. The abnormality determination information may also be configured as an update counter whose counter value changes at an accelerated rate each time an output signal is transmitted. In this case, the abnormality determination information may be configured to increase, for example, exponentially each time an output signal is transmitted. The abnormality determination information may also be configured to be a plurality of numerical values that change irregularly in a predetermined order, and the numerical values change in order each time an output signal is transmitted. In this case, even if the SENT communication waveform P is analyzed from the outside, the abnormality determination information will be difficult to analyze.

In the above embodiment, the first data compression unit 41 and the second data compression unit 42 compress the data amount of the first sensor data or the data amount of the second sensor data by the same compression method, but the present invention is not limited to this. For example, the first data compression unit 41 and the second data compression unit 42 may compress the data amount of the first sensor data or the data amount of the second sensor data by different compression methods. Specifically, the first data compression unit 41 may compress the data amount of the first sensor data by a lossless compression method, and the second data compression unit 42 may compress the data amount of the second sensor data by a lossy compression method. Also, the first data compression unit 41 may compress the data amount of the first sensor data by a lossy compression method, and the second data compression unit 42 may compress the data amount of the second sensor data by a lossless compression method.

It goes without saying that in the above-described embodiments, the elements constituting the embodiments are not necessarily essential, except in cases where they are specifically stated as essential or where they are clearly considered essential in principle.

In the above-described embodiments, when numerical values such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers, except when it is expressly stated that they are essential or when they are clearly limited to a specific number in principle.

In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., there is no limitation to those shapes, positional relationships, etc., unless specifically stated otherwise or in principle limited to a specific shape, positional relationship, etc.

(Features of the present invention)
[Claim 1]
A communication device that acquires a first detection value and a second detection value from a sensor (S1, S2) and outputs a signal according to the first detection value and the second detection value in a signal conforming to a SENT protocol,
a waveform generating unit (10) that generates a signal relating to the acquired first detection value and the second detection value as a SENT communication waveform;
A signal output unit (20) that outputs the SENT communication waveform as an output signal,
The SENT communication waveform is configured with a plurality of data areas in which information is stored,
The plurality of data areas include a first sensor area (R1) having a data length of 12 bits and storing information relating to the first detection value, and a second sensor area (R2) having a data length of 12 bits and storing information relating to the second detection value,
The waveform generating unit is
a sensor data creation unit (31, 32) that converts the first detection value into first sensor data that is 12-bit data to be stored in the first sensor area, and converts the second detection value into second sensor data that is 12-bit data to be stored in the second sensor area;
a data compression unit (41, 42) that compresses the amount of data of at least one of the first sensor data and the second sensor data to generate an empty area that does not include information in at least one of the first sensor area and the second sensor area;
and a discrimination information adding unit (50) that adds abnormality discrimination information to the empty area to determine whether or not a data fixation abnormality has occurred in which the first sensor data and the second sensor data are not updated.

[Claim 2]
The communication device according to claim 1 , wherein the data compression unit compresses an amount of data of both the first sensor data and the second sensor data to generate the empty area in both the first sensor area and the second sensor area.

[Claim 3]
The SENT communication waveform is formed such that the first sensor area for storing the first sensor data and the second sensor area for storing the second sensor data are adjacent to each other,
the data compression unit compresses an amount of data of the first sensor data to generate an empty area of 2 bits or more on a side of the first sensor area adjacent to the second sensor data, and compresses an amount of data of the second sensor data to generate an empty area of 2 bits or more on a side of the second sensor area adjacent to the first sensor data,
The communication device according to claim 2 , wherein the determination information adding unit adds the abnormality determination information having a data length of 4 bits or more to the empty area formed across the first sensor area and the second sensor area.

[Claim 4]
the data compression unit generates two free areas of 4 bits or more by compressing a data amount of each of the first sensor data and the second sensor data by 4 bits or more;
The communication device according to claim 2 , wherein the determination information adding unit adds the abnormality determination information having a data length of 4 bits or more to each of the two free areas.

[Claim 5]
The communication device according to claim 1 , wherein the data compression unit compresses an amount of data of only one of the first sensor data and the second sensor data to generate the empty area in one of the first sensor area and the second sensor area.

[Claim 6]
the data compression unit generates the free area of 3 bits or more by compressing a data amount of only one of the first sensor data and the second sensor data by 3 bits or more;
The communication device according to claim 5 , wherein the determination information adding unit adds the abnormality determination information having a data length of 3 bits or more to the free area.

[Claim 7]
7. The communication device according to claim 1, wherein the abnormality determination information includes an update counter whose counter value changes every time the output signal is transmitted.

[Claim 8]
The communication device according to claim 1 , wherein the data compression unit compresses the amounts of the first sensor data and the second sensor data using a lossless compression method.

[Claim 9]
The communication device according to claim 8 , wherein the data compression unit compresses the data amounts of the first sensor data and the second sensor data using Huffman coding.

[Claim 10]
The communication device according to claim 1 , wherein the data compression unit compresses the amounts of the first sensor data and the second sensor data using a lossy compression method.

[Claim 11]
The communication device according to claim 10 , wherein the data compression unit compresses the data amounts of the first sensor data and the second sensor data by logarithmic compression.

[Claim 12]
A sensor device comprising the communication device according to any one of claims 1 to 11,
A sensor device comprising a first sensor element (61) for detecting the first detection value and a second sensor element (62) for detecting the second detection value.

10 Waveform generating section 20 Signal output section 31, 32 Sensor data generating section 41, 42 Data compressing section 50 Discrimination information adding section R1 First sensor area R2 Second sensor area S1, S2 Sensor

Claims (12)

A communication device that acquires a first detection value and a second detection value from a sensor (S1, S2) and outputs a signal according to the first detection value and the second detection value in a signal conforming to a SENT protocol,
a waveform generating unit (10) that generates a signal relating to the acquired first detection value and the second detection value as a SENT communication waveform;
A signal output unit (20) that outputs the SENT communication waveform as an output signal,
The SENT communication waveform is configured with a plurality of data areas in which information is stored,
The plurality of data areas include a first sensor area (R1) having a data length of 12 bits and storing information relating to the first detection value, and a second sensor area (R2) having a data length of 12 bits and storing information relating to the second detection value,
The waveform generating unit is
a sensor data creation unit (31, 32) that converts the first detection value into first sensor data that is 12-bit data to be stored in the first sensor area, and converts the second detection value into second sensor data that is 12-bit data to be stored in the second sensor area;
a data compression unit (41, 42) that compresses an amount of at least one of the first sensor data and the second sensor data to generate an empty area in which the first sensor data and the second sensor data are not stored in at least one of the first sensor area and the second sensor area;
and a discrimination information adding unit (50) that adds abnormality discrimination information to the empty area to determine whether or not a data fixation abnormality has occurred, the data fixation abnormality indicating a state in which the first sensor data and the second sensor data are not updated. The communication device according to claim 1, wherein the data compression unit compresses the amount of data of both the first sensor data and the second sensor data to generate the empty area in both the first sensor area and the second sensor area. The SENT communication waveform is formed such that the first sensor area for storing the first sensor data and the second sensor area for storing the second sensor data are adjacent to each other,
the data compression unit compresses an amount of data of the first sensor data to generate an empty area of 2 bits or more on a side of the first sensor area adjacent to the second sensor data, and compresses an amount of data of the second sensor data to generate an empty area of 2 bits or more on a side of the second sensor area adjacent to the first sensor data,
The communication device according to claim 2 , wherein the determination information adding unit adds the abnormality determination information having a data length of 4 bits or more to the empty area formed across the first sensor area and the second sensor area. the data compression unit generates two free areas of 4 bits or more by compressing a data amount of each of the first sensor data and the second sensor data by 4 bits or more;
The communication device according to claim 2 , wherein the determination information adding unit adds the abnormality determination information having a data length of 4 bits or more to each of the two free areas. The communication device according to claim 1, wherein the data compression unit compresses the amount of data of only one of the first sensor data and the second sensor data to generate the empty area in one of the first sensor area and the second sensor area. the data compression unit generates the free area of 3 bits or more by compressing a data amount of only one of the first sensor data and the second sensor data by 3 bits or more;
The communication device according to claim 5 , wherein the determination information adding unit adds the abnormality determination information having a data length of 3 bits or more to the free area. The communication device according to any one of claims 1 to 6, wherein the abnormality determination information includes an update counter whose counter value changes each time the output signal is transmitted. The communication device according to any one of claims 1 to 6, wherein the data compression unit compresses the amount of data of the first sensor data and the second sensor data using a lossless compression method. The communication device according to claim 8, wherein the data compression unit compresses the amount of data of the first sensor data and the second sensor data using Huffman coding. The communication device according to any one of claims 1 to 6, wherein the data compression unit compresses the amount of data of the first sensor data and the second sensor data using a lossy compression method. The communication device according to claim 10, wherein the data compression unit compresses the amount of data of the first sensor data and the second sensor data by logarithmic compression. A sensor device including the communication device according to claim 1,
A sensor device comprising a first sensor element (61) for detecting the first detection value and a second sensor element (62) for detecting the second detection value.

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