JP3599150B2 - Automatic tracking system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a self-driving vehicle (auto-driving vehicle, which is driven by detecting a marker (also referred to as a position marker or a marker) such as a magnetic nail (magnetic nail) disposed on a traveling path. Car or self-propelled car) is the front car, and the self-driving car that runs while detecting the marker from the rear side of the front car is also the following car. To Related.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an automatic vehicle storage system that automatically stores a vehicle at a predetermined location in a parking lot and an automatic vehicle travel system that automatically runs on a highway by a vehicle have been considered.
[0003]
As this vehicle automatic traveling system, for example, there is an AHS (Automated Highway System) advanced by the Ministry of Construction, and this AHS automatic operation is an automatic operation in which magnetized nails, that is, magnetic nails (magnetic nails) are laid at predetermined intervals. A self-driving road system is one in which the vehicle travels along a course for use while detecting the attitude of the vehicle and performs automatic driving.
[0004]
The technology related to this automatic driving road system is described in, for example, Japanese Patent Application No. 7-283973. In this technology, a magnetic sensor is provided at a center of a traveling path at a constant interval along a traveling direction, for example, at 1 m, on a traveling path for guiding a vehicle on which a magnetic nail of N polarity is laid, specifically, a magnetic sensor. This technology detects magnetism with a vehicle and automatically drives the vehicle.
[0005]
Therefore, in this technology, basically, it is possible to confirm the traveling speed of the vehicle by counting the number of magnetic information sources at regular intervals, and to arrange the magnetic sensors at the front and rear of the vehicle. Thus, the attitude of the own vehicle with respect to the magnetic information source, in other words, the attitude with respect to the traveling road, that is, the yaw angle can be detected from the strength of the magnetic fields received by the two magnetic sensors.
[0006]
Further, on the vehicle guidance traveling path (also simply referred to as a course), at predetermined distances, for example, every 500 m, section information in which N poles and S poles indicating the head information (section number) of the section are mixed. An NS bit string portion is provided for detecting the section information NS bit string portion to detect the position of the own vehicle on the vehicle guidance travel path.
[0007]
For example, since the section number starts from the value 0 and sequentially increases to the values 1, 2, 3,..., The section number is multiplied by the predetermined distance (predetermined section distance), and the section number location By counting the number of magnetic nails from to the current position, the position of the own vehicle on the course can be grasped. Accordingly, the position Xb of the preceding vehicle on the course is received from the preceding vehicle, and the following expression (1) representing the position Xb of the preceding vehicle on the course represents the following position Xa representing the position Xa of the own vehicle: By subtracting the equation (2), the following distance (also referred to as an inter-vehicle distance) Lba shown in the following equation (3) can be obtained.
[0008]
Xb = predetermined distance × section number + number of magnetic nails up to the current position in the section (1)
Xa = predetermined distance × section number + number of magnetic nails up to the current position in the section (2)
Lba = Xb-Xa (3)
For example, as illustrated in FIG. 10, for example, as shown in FIG. 10, a predetermined interval Lu (a unit interval) is continuously provided on a traveling path (traveling path, vehicle guideway, traveling course or simply course) RD. , Where Lu = 1 m.) A predetermined distance (predetermined section) Lp (here, an N-pole magnetic nail) Mn indicated by a reference sign (hereinafter simply referred to as an N-pole nail) Mn arranged in a line. , Lp = 500 m). An S-pole magnetic nail Ms (also simply referred to as an S-pole nail) Ms is arranged at the beginning of the section at the beginning of the section and indicated by a symbol ● indicating a break of the section. Are the first bits a1 and a2 of the section. Then, successively to the section head bits a1 and a2, for example, section numbers b1 and b2 of 4 bits, which represent section numbers on the downstream side in the traveling direction (arrow direction) Q of the vehicle (not shown), are arranged. In this case, the section information NS bit string A1 of the first section is composed of the section head bit a1 and the section number b1, and the section information NS bit string A2 of the second section is composed of the section head bit a2 and the section number b2. Be composed.
[0009]
In the example of FIG. 10, for example, the N-pole nail Mn is set to a binary bit “1”, the S-pole nail Ms is set to a binary bit “0”, and the bits on the upstream side in the traveling direction Q of the section numbers b1 and b2. Is the LSB, and the bit on the downstream side in the traveling direction Q of the section numbers b1 and b2 is the MSB. With this definition, the detection order of the section number b1 is “1000”, but the section number is “0001”, which is the reverse of the section number, and the first section number is significant code. Can be read. Similarly, the detection order of the section number b2 is “0100”, but the section number is “0010” obtained by rearranging the section number in reverse order, and the second section number can be read as a meaningful code.
[0010]
In this case, the preceding vehicle (not shown) is located, for example, at the point where the 25th magnetic nail Mn has passed from the section head bit a2 in the second section, and the following vehicle is the section head bit a1 in the first section. For example, assuming that the vehicle is located at a point that has passed the 410th magnetic nail, the position Xb on the course of the preceding vehicle can be calculated as Xb = 2 (2 in the second section) × 500 ( m) +25 (25th 25th) × 1 (m) = 1,025 (m), and the position Xa of the following vehicle on the course is similarly Xa = 1 × 500 + 410 × 1 = from the above equation (2). 910 (m) is calculated. Therefore, since the inter-vehicle distance Lba is a difference between them, it can be calculated as Lba = 1020−910 = 110 (m).
[0011]
[Problems to be solved by the invention]
As described above, in the above-described technology, the following vehicle receives the position of the preceding vehicle on the course, and subtracts the position of the own vehicle on the course from the position of the preceding vehicle on the course. The distance between the vehicle and the preceding vehicle can be determined.
[0012]
However, if the following vehicle enters the course from the middle of the section at the junction, etc., the inter-vehicle distance cannot be calculated until the section number displayed at the beginning of the next section is read. There are issues.
[0013]
Also, there is a problem that the inter-vehicle distance cannot be calculated correctly even when a reading error occurs in the section number displayed at the beginning of the section.
[0014]
The present invention has been made in consideration of such a problem, and is intended for a case in which an error occurs in reading a section number even when the vehicle enters from a middle of a section of a traveling road on which markers are arranged. Automatic tracking system that can accurately calculate the following distance Time The purpose is to provide.
[0015]
[Means for Solving the Problems]
The automatic tracking system according to the present invention includes:
Equipped with a preceding car and a following car that follows it,
The preceding vehicle is
Marker detection means for detecting markers installed at arbitrary intervals on the traveling path,
Marker interval calculation means for calculating the distance between the detected markers,
Having a transmitter to transmit the calculated marker interval data to the following vehicle side,
The following vehicle is
A receiver for receiving the transmitted marker interval data of the preceding vehicle,
Storage means for storing the received marker interval data;
Marker detection means for detecting markers installed at arbitrary intervals on the traveling path,
Marker interval calculation means for calculating the distance between the detected markers,
An inter-vehicle distance calculating unit that calculates an inter-vehicle distance between the host vehicle and the preceding vehicle from the calculated marker interval data of the own vehicle and the received marker interval data of the preceding vehicle.
It is characterized by the following.
[0016]
According to this invention, the following vehicle (own vehicle) compares the marker interval data of the own vehicle with the marker interval data of the preceding vehicle by the following distance calculation means, and moves forward from the detected position of the corresponding marker interval data. The inter-vehicle distance between the traveling position of the vehicle and the traveling position of the own vehicle can be calculated.
[0017]
In this case, the marker interval measured by the own vehicle is stored as continuous data, and the data of the marker interval measured by the preceding vehicle is received by inter-vehicle communication, and the cross-correlation function of both the marker interval continuous data is calculated. By detecting a data sequence that is more similar to the preceding vehicle, a distance difference from the preceding vehicle, that is, an inter-vehicle distance can be calculated.
[0018]
Note that the inter-vehicle distance is, more precisely, the calculated inter-vehicle distance plus the mileage data from the last marker detected by the preceding vehicle, and further subtracts the mileage data from the last marker detected by the own vehicle. It can be obtained by:
[0019]
The above-mentioned automatic following system can be applied to an automatic following vehicle.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Components corresponding to those shown in FIG. 10 are denoted by the same reference numerals. In addition, FIG. 10 is also referred to as necessary in order to avoid the complexity of duplicating drawings.
[0021]
FIG. 1 shows a schematic configuration of an automatic tracking system 100 to which an embodiment of the present invention is applied. The automatic following system 100 travels along a preceding vehicle (a leading vehicle) 110 that travels in a direction indicated by an arrow Q on a travel path RD (see also FIG. 10) such as an expressway. (Following) a follower vehicle (a vehicle, a follower vehicle) 130.
[0022]
In this embodiment, the travel path RD is the same as that shown in FIG. 10, and if briefly described again, a substantially constant predetermined distance Lu along the travel direction Q at the center of the travel path, for example, This is a vehicle guidance runway in which a magnetic information source with Lu = 1 m, specifically, a magnetic nail (N-pole nail) Mn of N polarity corresponding to the bit “1” represented by the symbol ○ is laid in a line. In this case, an NS bit string for section information in which N poles and S poles coexist at the beginning of the section (section number) at every predetermined distance (predetermined section) Lp, for example, Lp = 500 m, on the traveling path RD. Parts A1, A2 and the like are arranged. In the section information NS bit string sections A1, A2, etc., at the beginning of the section, an S pole nail Ms corresponding to a bit “0” represented by a symbol ● indicating a delimiter of the section is arranged. The bits are a1 and a2. Then, successively to the section head bits a1 and a2, for example, section numbers b1 and b2 of 4 bits indicating the section number are arranged downstream of the traveling direction (arrow direction) Q. In this case, the section information NS bit string portion A1 of the first section is composed of a section head bit a1 and a section number b1, and the section information NS bit string section A2 of the second section is a section head bit a2 and a section number b2. It is composed of The bits on the upstream side of the section numbers b1 and b2 are LSB, and the bits on the downstream side in the traveling direction Q of the section numbers b1 and b2 are MSB. In the following description, the N-pole nail Mn and / or the S-pole nail Ms are also simply referred to as magnetic nails M.
[0023]
It should be noted that the information sources, that is, markers, arranged at substantially constant intervals on the vehicle guidance driving path RD are not limited to magnetic nails Mn (Ms) as magnetic information sources, but may be replaced with optical information sources or electrical information sources. be able to.
[0024]
In FIG. 1, the leading vehicle 110 and the following vehicle 130 have basically the same configuration, and software to be selected depends on whether the vehicle is used as the leading vehicle 110 or the following vehicle 130. different. Therefore, in the following description, the corresponding components of the preceding vehicle 110 and the following vehicle 130 are denoted by the same reference numerals, and if necessary, “for the preceding vehicle 110” or “for the following vehicle 130” or the like. The explanation will be given with the limitation.
[0025]
The leading vehicle 110 and the following vehicle 130 basically have a communication module 1, a control planning module 2, a lateral control module 3, and a vehicle speed control module 4, respectively. Is configured to transmit and receive data to and from the modules 1, 3, and 4. In this case, the control planning module 2 and the vehicle speed control module 4 constitute a preceding vehicle following control means.
[0026]
In this embodiment, a module is a standardized unit or component, and usually refers to a component having various defined functions therein. In this embodiment, a module includes It includes a CPU functioning as control / judgment means, a ROM, a RAM as storage means, a counting means such as a counter, and a timing means such as a timer. The “module” is an object and is also called an apparatus.
[0027]
The communication module 1 is connected to a communication (functioning as a transmitting antenna or a receiving antenna) for road-vehicle communication and a communication antenna (functioning as a transmitting antenna or a receiving antenna) 11 for vehicle-to-vehicle communication.
[0028]
The communication antenna 7 for road-to-vehicle communication transmits command speed information, road curvature information, traffic congestion information, an emergency message, and the like from a leaky coaxial (LCX) cable 140 that is continuously arranged along the road side of the traveling road RD. Receive. The end of the LCX cable 140 is connected to a base station (not shown), which is an information transmission and transmission source. The leading vehicle 110 and the following vehicle 130 transmit the identification (ID) number of the own vehicle to the base station (not shown) or another vehicle via the communication antenna 7 via the LCX cable 140.
[0029]
Based on the detected position of the ID number, the base station can grasp the traveling position of each of the vehicles 110 and 130.
[0030]
Using the communication antenna 11 for inter-vehicle communication, a traveling locus, a traveling distance, a vehicle speed, longitudinal acceleration data (vehicle speed planning data), and the like are transmitted and received between the preceding vehicle 110 and the following vehicle 130.
[0031]
The control planning module 2 includes a yaw rate sensor 5 for detecting a lateral angular velocity of the vehicle, a magnetic nail sensor (marker detecting means) 6 for detecting the magnetic nail Mn (Ms), and one pulse generated by one rotation of the wheel. The output of the wheel pulse sensor 8 and the output of the start switch 12 for automatic driving (automatic driving) are supplied. In practice, as shown in FIG. 2, the magnetic nail sensors 6 are fixed as magnetic sensors 6f and 6r on the lower axle U of the bumpers before and after the vehicles 110 and 130, respectively. The magnetic sensors 6f and 6r also detect displacement of the vehicle in the vehicle width direction H (displacement from the axle U). The control plan module 2 supplies an output to the audio output device 17 and the display device 18.
[0032]
The output of the yaw rate sensor 5 is supplied to the lateral control (steering control) module 3. The lateral control module 3 supplies an output by feedback control to an actuator (also referred to as EPS) 14 which is an EPS (Electric Power Steering) device provided in a steering operation transmission system. Here, the steering control by the lateral control module 3 will be briefly described.
[0033]
As shown in FIG. 2, the displacement in the vehicle width direction H is based on the magnetic field distribution of the magnetic nail Mn (the magnetic field distribution which is the maximum just above the magnetic nail Mn and attenuates substantially in a bell shape toward the periphery) by the magnetic sensors 6 f and 6 r. Can be calculated by detecting Therefore, the lateral direction control module 3 controls the EPS 14 so that the yaw angle θ of the vehicle 110 (130) (the angle between the direction of the axle U and the laying direction T of the magnetic nail, that is, the running path RD) becomes θ = 0 °. Feedback control. The yaw angle θ can be calculated by integrating the yaw rate (rad / sec), which is the output signal of the yaw rate sensor 5, with time.
[0034]
In FIG. 1 again, the output of the wheel pulse sensor 8, the longitudinal acceleration sensor 9, the laser radar 10, and the brake pedal switch 13 are supplied to the vehicle speed control module 4. The vehicle speed control module 4 includes an actuator (also referred to as a throttle CBW) 15 that is a throttle CBW (Controlled By Wire) provided in a throttle system and an actuator (brake pressure control brake) that is a boost pressure control brake provided in a brake system. The output is supplied to 16. The throttle CBW 15 and the brake pressure control brake 16 are also electronically controlled similarly to the EPS 14.
[0035]
Next, a control operation of the automatic tracking system 100 according to this embodiment will be described with reference to a flowchart shown in FIG. The subject of the control is any of the modules 1 to 4.
[0036]
The control plan module 2 confirms that the automatic traveling start switch 12 is in an ON state, and starts creating information for automatic following traveling (step S1).
[0037]
Next, it is confirmed whether or not the brake pedal switch 13 is off (step S2). When it is in the ON state, that is, when the brake is artificially applied, the next step S The control processing after 3 is not performed.
[0038]
When both the conditions of step S1 and step S2 are satisfied, specifically, when the start switch 12 is on and the brake pedal switch 13 is off, the processing after step S3 is performed.
[0039]
The process of step S3 includes a process of calculating the position of the current vehicle (in this case, the following vehicle 130) (also referred to as current position coordinates) Xa, a process of calculating the own vehicle speed Va, and the own vehicle acceleration Aa. Is a calculation process.
[0040]
When the section number b1 is read by the control planning module 2 through the magnetic nail sensor 6, the own vehicle position Xa, that is, the position Xa on the course, as described in the section of the related art, is expressed by the above equation (2). Can be calculated more easily. However, when an error occurs in reading the section number b1 or the like, or when the vehicle enters (joins) the traveling path RD from the middle of the section between the section number b1 and the section number b2 during the traveling path RD. Until the vehicle travels to a position such as the next section number b2, the section number is unknown.
[0041]
When the preceding vehicle 110 does not exist, the vehicle may travel at a predetermined speed while detecting the magnetic nail Mn until the first section information NS bit string portion An (in this case, An = A2) is read.
[0042]
When the preceding vehicle 110 exists, the detection process (calculation process) of the inter-vehicle distance Lba with the preceding vehicle 110 according to the main part of the present invention is started.
[0043]
The calculation process of the inter-vehicle distance Lba will be described based on a functional block diagram of the inter-vehicle distance calculation means 150 shown in FIG. The vehicle-to-vehicle distance calculating means 150 is basically composed of the magnetic nail sensor 6, the communication antenna 11, the communication module 1, the control planning module 2, and the software installed in the modules 1, 2.
[0044]
In this case, the following vehicle 130 stores the marker interval Lu (see FIG. 10), which is the distance between adjacent magnetic nails Mn (Ms) measured by the marker interval measuring unit 152, in the storage unit 154 (for example, the RAM in the control planning module 2). ), The latest measured value is stored as the own vehicle measurement data string 160 of continuous data with the head as the head.
[0045]
The marker interval measuring means 152 continuously measures the marker interval Lu based on the outputs of the marker passage detecting means 156 and the traveling distance pulse output means 158. The marker passage detecting means 156 uses the magnetic nail sensor 6, and the traveling distance pulse output means 158 uses the wheel pulse sensor 8. In this case, since the pulse interval of the wheel pulse sensor 8 can be converted as a predetermined distance, the ratio of the output pulse interval of the wheel pulse sensor 8 to the output pulse interval of the magnetic nail sensor 6 is used to calculate the magnetic nail Mn (Ms). The interval Lu can be accurately measured. Further, the marker interval measuring means 152 calculates the latest measured value, in other words, the traveling distance data ΔLa from the detection point of the last marker, that is, an accurate current position, and calculates the subtraction input of the adder / subtractor which is the adjusting means 170. Supply to terminal. This travel distance data ΔLa is a distance corresponding to a time between the marker passing detection time point and the calculation time point by the adjusting means 170 mainly considering the calculation time of the cross-correlation function (described later).
[0046]
Note that the magnetic nail Mn (Ms) as a marker is buried at regular intervals (specification distance or predetermined distance), that is, at every 1 m, macroscopically (in terms of specifications). , 1.00 m, but a burial variation of about ± 5 cm exists. Therefore, microscopically, the magnetic nail interval Lu is an arbitrary interval. The present invention focuses on this arbitrary interval.
[0047]
Similarly, the marker interval of the leading vehicle 110 sent from the leading vehicle 110 by the inter-vehicle communication means 162 at any time is stored in the storage means 154 as a leading vehicle measurement data sequence 161 of continuous data with the latest measured value at the top. In addition, the traveling distance data ΔLb from the preceding vehicle last detection marker at that time is supplied to the addition input terminal of the adjusting means 170. Further, the position Xb {see equation (2)} of the preceding vehicle 110 on the course at that time is supplied to the addition input terminal of the adjusting means 172 which is a subtractor.
[0048]
FIG. 5 shows an actual measurement example of the preceding vehicle measurement data sequence 161 stored in the storage means 154. The horizontal axis is the time as address i, and the vertical axis is the marker interval measurement value. From FIG. 5, it can be seen that the preceding vehicle measurement data sequence 161 has a waveform shape having a certain characteristic.
[0049]
Next, the normalization means 164 performs a normalization process using the following equation (4) so that the average values of both data strings 160 and 161 match.
[0050]
y (j) = {bar x (i) / bar y ′ (j)} × y ′ (j) (4)
here,
j is a measurement point (address) of the own vehicle measurement data sequence 160, and j = 1, 2,.
i is a measurement point (address) of the preceding vehicle measurement data sequence 161 and i = 1, 2,..., N (where M <N),
x (i) is an observation waveform, and the preceding vehicle measurement data sequence 161,
Bar x (i) is the average of x (i),
y ′ (j) is a waveform to be searched, and the vehicle measurement data sequence 160,
The bar y '(j) is the average of y' (j),
y (j) is the normalized vehicle measurement data sequence.
[0051]
Note that this normalization processing means that calibration is performed so that the outputs of the distance sensors that measure the marker interval, that is, the outputs of the marker passage detection unit 156, the traveling distance pulse output unit 158, and the marker interval measurement unit 152 match. I do.
[0052]
However, if the distance sensor has been calibrated in advance by some means, this normalization processing is unnecessary. However, in the normal case, the section number cannot be read until after the section, so that the section merges with the travel path RD. In some cases, this normalization processing is required.
[0053]
Next, the cross-correlation function Rxy (i) of both data strings y (j) and x (i) is calculated by the correlation function calculation / phase difference detection means 166 to detect the phase difference.
[0054]
The cross-correlation function Rxy (i) moves the waveform of the data sequence y (j) of the following vehicle 130 having a small number of data at every address with respect to the data sequence x (i) of the preceding vehicle 110 having a large number of data. However, it can be calculated by the following equation (5) in the form of taking the product sum of the corresponding positions. Although the calculation of the correlation value at both ends of the data string x (i) having a small number of sums of products is a formula different from the formula (5), the reliability is reduced. I haven't.
[0055]
Rxy (i) = (1 / M) Σ (j = 1 → M) ｛x (i + j) · y (j)｝ (5)
However,
i = 0, 1, 2,..., NM,
Σ (j = 1 → M) means a Σ operation from j = 1 to j = M, that is, a sum operation. Therefore, in this case, it means a product-sum operation of {x (i + j) .y (j)}.
[0056]
According to the calculation result of the cross-correlation function Rxy (i) according to the equation (5), the waveform of the data sequence y (j) of the following vehicle 130 having a small number of data is the data sequence x (i) of the preceding vehicle 110 having a large number of data. ), A peak appears at the time (point) where the peak value peak {Rxy (ip)} is obtained, that is, by detecting the phase difference, the following equation (6) is obtained. This phase difference ip is converted into a distance, that is, inter-vehicle distance data Lba.
[0057]
Lba = Lu × ip (6)
Lu is a specified value (specified value) of the marker interval. In this embodiment, Lu = 1 m may be used.
[0058]
The processing including the cross-correlation processing up to the expression (6) will be described in more detail with reference to FIG. 6, the symbol x (i) depicts the data sequence 161 of the measured marker interval values of the leading vehicle 110 shown in FIG. 5, and the symbol y (j) is the normalized following vehicle 130. The vehicle measurement data sequence is drawn. The symbol Rxy (i) indicates the calculation result of the cross-correlation function.
[0059]
By moving the waveform of the own vehicle measurement data sequence y (j) to the right side with i = 1, 2,..., When i = ip, the correspondence of the preceding vehicle measurement data sequence x (i) Both waveforms coincide in the section Lcp. The cross-correlation function Rxy (i) is obtained when the waveform of the data sequence y (j) of the following vehicle 130 having a small number of data matches the waveform of the data sequence x (i) of the preceding vehicle 110 having a large number of data (point). ), The distance (phase difference) from 0, 1, 2,..., Ip to the point i = ip at which the peak value peak {Rxy (ip)} appears is the inter-vehicle distance Lba (Lba = Lu × ip). ).
[0060]
The position Xa (Xa = Xb−Lba) of the own vehicle 130 on the course can be calculated from the inter-vehicle distance Lba calculated in this way, but the more accurate inter-vehicle distance Lba ′ is calculated by the adjusting means 170.
[0061]
That is, it can be easily understood that the more accurate inter-vehicle distance Lba 'can be obtained by the following equation (7) with reference to FIG.
[0062]
Lba ′ = Lba + ΔLb−ΔLa (7)
The accurate position Xa of the following vehicle 130 on the course at this time can be calculated by the following equation (8) by the adjusting means 172 which is a subtractor (see FIG. 7).
[0063]
Xa = Xb-Lba '(8)
The above is the description of the calculation process of the vehicle position Xa in step S3. In the process of calculating the cross-correlation function described above, after detecting the section number on the course once, the positions Xb and Xa on the course are calculated by the equations (1) to (3) described in the section of the related art. Alternatively, the process may be changed to a process for obtaining the inter-vehicle distance Lba.
[0064]
Next, the process of calculating the own vehicle speed Va during the process of step S3 will be described.
[0065]
In the case of performing the auto-following traveling, the position Xb of the preceding vehicle 110 on the course and the speed Vb of the preceding vehicle, the position Xa of the host vehicle (following vehicle) 130 on the course, the speed Va, and the target inter-vehicle distance Lo Based on this, it is determined whether the predicted position and speed of the preceding vehicle 110 and the following vehicle 130 after T seconds are appropriate, and the required acceleration of the own vehicle (the following vehicle) 130 at the present time is planned, and the throttle CBW 15 or It is necessary to drive the boost pressure control brake 16, and therefore, it is necessary to calculate the speeds Va and Vb.
[0066]
FIG. 8 shows a configuration example of the speed calculation means 180. The speed calculating means 180 is basically composed of the magnetic nail sensor 6, the control plan module 2, and the software installed in the control plan module 2.
[0067]
Each time the output pulse of the marker passage detecting means 156 using the magnetic nail sensor 6 is supplied to the time reading means 182, the time reading means 182 reads the time of the timer 184 in synchronization with this output pulse and reads at least two times. The time is sequentially stored in a storage circuit 186 capable of storing the time.
[0068]
By subtracting the current storage time from the previous storage time by the subtractor 188, the elapsed time during that period, that is, the required time between adjacent markers is calculated.
[0069]
The speed (vehicle speed) V (Va, Vb) can be calculated by dividing the elapsed time by a specified distance (distance on specification, predetermined distance) Lu between the markers.
[0070]
This speed calculation result seems to have a problem with the dispersion of the marker laying intervals. However, in practice, both the leading vehicle 110 and the following vehicle 130 are traveling on the same traveling path RD, so the same variation is caused. This causes the algorithm to cancel each other in a short time algorithmically when following. Therefore, the following performance has almost no effect.
[0071]
The vehicle speed may be calculated by counting pulses output from the wheel pulse sensor 8 every time the vehicle travels a certain distance for a certain period of time, or by measuring the pulse interval time. However, when the vehicle speed obtained in this way is received by the inter-vehicle communication and the following vehicle 130 is to be controlled to the same vehicle speed as the preceding vehicle 110, the distance obtained by the running pulse between the vehicles is corrected and matched. Otherwise, even if the same speed is calculated, a speed difference occurs, and accurate tracking cannot be performed. In addition, even if the traveling distances are corrected, an error occurs in the traveling distance due to a change in the air pressure of the wheels or a slip. Such a problem is solved by the vehicle speed V calculated by the speed calculating means in FIG.
[0072]
The above is the description of the process of calculating the own vehicle speed Va during the process of step S3.
[0073]
Next, the acceleration Aa of the own vehicle can be easily obtained by differentiating the own vehicle speed Va with respect to time. Thus, the process of step S3 ends.
[0074]
Next, the vehicle position Xat, the vehicle speed Vat, and the vehicle acceleration Aat after a lapse of a predetermined time (T seconds) are predicted (step S4). It has been confirmed by experiments that the fixed time T is selected to be about 1 to 2 seconds so that the following vehicle 130 can smoothly follow the preceding vehicle 110. Here, T = 1.5 seconds is selected. I have.
[0075]
It is easily understood that the own vehicle position Xat and the own vehicle speed Vat after T seconds can be calculated from the present own vehicle position Xa, the speed Va, and the acceleration Aa by the following expressions (9) and (10). .
[0076]
Xat = Xa + Va · T + (1/2) Aa · T ² … (9)
Vat = Va + Aa · T (10)
Next, position information and speed information of the preceding vehicle 110 are received from the preceding vehicle 110 (step S5).
[0077]
The control plan module 2 calculates the preceding vehicle acceleration Ab by differentiating the received preceding vehicle speed Vb (step S6).
[0078]
Next, the leading vehicle position Xbt and the leading vehicle speed Vbt of the leading vehicle 110 after T seconds are calculated by the following equations (11) and (12) corresponding to the above equations (9) and (10). Ask.
[0079]
Xbt = Xb + Vb.T + (1/2) Ab.T ² … (11)
Vbt = Vb + Ab · T (12)
The vehicle speed control module 4 calculates the own vehicle position Xat after T seconds, the own vehicle speed Vat after T seconds, the preceding vehicle position Xbt after T seconds, and the after T seconds calculated by the expressions (9) to (12). To determine whether to control the throttle CBW 15 to increase the speed of the own vehicle 130 or to control the boost pressure brake 16 to reduce the speed of the own vehicle 130 based on the preceding vehicle speed Vbt. Is calculated (step S8).
[0080]
FIG. 9 shows a detailed flowchart of a subroutine for calculating the designated acceleration Ap. Therefore, first, a predicted position difference (predicted inter-vehicle distance) Dp (Dp = Xbt-Xat) between the preceding vehicle 110 and the own vehicle 130 after T seconds, that is, a calculated inter-vehicle distance is obtained (step S8a).
[0081]
Next, a difference Lp (Lp = Dp-L) between the position difference Dp and the target inter-vehicle distance L is determined (step S8b).
[0082]
The difference Lp is multiplied by the position gain constant Kp to obtain Lp · Kp (step S8c).
[0083]
Similarly, a predicted speed difference Dv (Dv = Vbt-Vat) between the preceding vehicle 110 and the own vehicle 130 after T seconds is obtained (step S8d).
[0084]
Dv · Kv is obtained by multiplying the obtained speed difference Dv after T seconds by the speed gain constant Kv (step S8e).
[0085]
The command acceleration Ap is obtained by combining the results of step S8c and step S8e (step S8f). The designated acceleration Ap can be obtained by the following equation (13).
[0086]
Ap = Lp · Kp + Dv · Kv (13)
Next, returning to the main routine shown in FIG. 3, it is determined whether or not the obtained designated acceleration Ap is a zero value (Ap = 0) (step S9).
[0087]
If Ap = 0, the vehicle may continue running at the current throttle opening and brake pressure, and the process returns to step S1 without performing any processing.
[0088]
If Ap ≠ 0, an integration process of converting the indicated acceleration Ap into a throttle opening and adding it to the previous throttle opening is performed (step S10), and the throttle CBW 15 is controlled based on the value of the integration result. Performs processing to increase or decrease the vehicle speed.
[0089]
On the other hand, the command acceleration Ap is also input in parallel to the brake control processing. An integral process of converting the commanded acceleration Ap into a brake pressure and adding the same to the previous brake pressure is performed (step S12), and the boost pressure control brake 16 is controlled based on the integration result to apply a brake or release the brake. (Step S13).
[0090]
Note that the duty of the control pulse is normally calculated for controlling the throttle CBW 15 and boost pressure control.
[0091]
In addition, in any control, the control using the integration process (integration means) is performed in order to avoid a sudden change in the designated acceleration Ap due to a missing data or the like in advance. In other words, this is because the following control of the preceding vehicle 110 is smoothly performed by making the speed change gradual.
[0092]
Note that the processing of steps S10 and S11 and the processing of steps S12 and S13 are preferably performed in parallel to improve processing speed.
[0093]
By performing the above-described vehicle speed control processing, the following vehicle 130 can run smoothly while maintaining a substantially target inter-vehicle distance (generally, a constant inter-vehicle distance) Lba ′ with respect to the preceding vehicle 110.
[0094]
Note that, under the control of the control plan module 2, the speed of the own vehicle 130, the speed of the preceding vehicle 110, the speed difference between the own vehicle and the preceding vehicle, the actual speed, Among the inter-vehicle distance, the target inter-vehicle distance, and the difference between the actual inter-vehicle distance and the target inter-vehicle distance, it is possible to output necessary ones from the speaker via the audio output device 17. The positions of the own vehicle 130 and the preceding vehicle 110 can be displayed above.
[0095]
It should be noted that the present invention is not limited to the above-described embodiment, but may adopt various configurations without departing from the gist of the present invention.
[0096]
【The invention's effect】
As described above, according to the present invention, the following vehicle (own vehicle) uses the inter-vehicle distance calculating means to calculate the marker interval data of the own vehicle and the marker interval data of the preceding vehicle obtained by communication from the preceding vehicle. As a result, the effect that the inter-vehicle distance between the traveling position of the preceding vehicle and the traveling position of the own vehicle can be calculated from the detected position of the corresponding marker interval data.
[0097]
In this case, the corresponding marker interval data can be calculated more accurately by calculating the cross-correlation function of both the marker interval data, and as a result, the effect that the accurate inter-vehicle distance can be calculated is achieved. Is done.
[0098]
Also, when calculating the inter-vehicle distance, add the mileage data from the last detected marker of the preceding vehicle to the calculated inter-vehicle distance and further reduce the mileage data from the last detected marker of the own vehicle. Thus, it is possible to eliminate a calculation error in one marker section.
[0099]
Furthermore, since the inter-vehicle distance is calculated based on the marker interval instead of the inter-vehicle distance based on the section number, when the following vehicle enters the course from the middle of the section at the junction, etc. The effect that the inter-vehicle distance can be calculated even before the section number displayed at the head of the section is read is achieved.
[0100]
Furthermore, since the section number is not used when calculating the inter-vehicle distance, the effect that the inter-vehicle distance can be correctly calculated even when a reading error of the section number displayed at the head of the section occurs. Is achieved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a plan view used for explaining steering angle control.
FIG. 3 is a flowchart of a mail routine used for explaining the vehicle speed control in the example of FIG. 1;
FIG. 4 is a functional block diagram illustrating a configuration example of an inter-vehicle distance calculation unit;
FIG. 5 is a graph showing measured values of marker intervals.
FIG. 6 is a graph used for explaining a cross-correlation function process.
FIG. 7 is an explanatory diagram provided for explaining more accurate inter-vehicle distance calculation.
FIG. 8 is a functional block diagram illustrating a configuration example of a speed calculation unit.
FIG. 9 is a flowchart of a subroutine relating to an instruction acceleration calculation process in the flowchart of FIG. 2;
FIG. 10 is an explanatory diagram showing an example of laying a marker.
[Explanation of symbols]
1. Communication module 2. Control planning module
3: lateral control module 4: vehicle speed control module
100: Automatic tracking system 110: Car in front
130: Following vehicle 150: Inter-vehicle distance calculating means

Claims (2)

Equipped with a preceding car and a following car that follows it,
The preceding vehicle is
Marker detection means for detecting markers installed at arbitrary intervals on the traveling path,
Marker interval calculation means for calculating the distance between the detected adjacent markers,
Having a transmitter to transmit the calculated marker interval data to the following vehicle side,
The following vehicle is
A receiver for receiving the transmitted marker interval data of the preceding vehicle ,
A marker detection means for detecting an installed markers at arbitrary intervals on the run path,
Marker interval calculation means for calculating the distance between the detected adjacent markers,
Storage means for storing the marker interval calculated for the own vehicle as continuous vehicle marker interval continuous data, and for storing the marker interval calculated for the preceding vehicle transmitted from the preceding vehicle as preceding vehicle marker interval continuous data; and ,
An inter-vehicle distance calculating means for calculating a cross-correlation function between the following vehicle marker interval continuous data and the preceding vehicle marker interval continuous data, and calculating an inter-vehicle distance between the own vehicle and the preceding vehicle based on the calculation result. And an automatic following system. In claim 1 Symbol mounting system,
The preceding vehicle has a traveling distance calculation unit from a preceding vehicle last detection marker for calculating traveling distance data from a last detected marker, and calculates the traveling distance data from the preceding vehicle last detection marker. Transmit to the following vehicle side by the transmitter,
The following vehicle has a traveling distance calculation unit from the own vehicle last detection marker for calculating the traveling distance data from the last marker detected by the marker detection unit of the own vehicle,
The inter-vehicle distance calculating means adds the traveling distance data from the preceding vehicle last detection marker to the calculated inter-vehicle distance, and further calculates a distance obtained by subtracting the traveling distance data from the own vehicle last detection marker with the calculated inter-vehicle distance. An automatic tracking system characterized by:

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