JPS6316692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an in-vehicle course guidance system with an offset warning mechanism, in particular, an electronic display mounted on the driver's seat of a passenger car, and a map showing roads etc. on the display screen of the display. In a course guidance system that extracts the location of the vehicle using a direction sensor and a speed sensor mounted on the vehicle body, plots it on the display, and guides the driving course by correlating it with the map. Each time the vehicle continues to drive for a certain period of time, a warning message is output on the display, for example, to warn the driver to offset the direction sensor in order to reduce the influence of cumulative errors caused by the drift of the direction sensor. This invention relates to an on-vehicle course guidance system with an offset warning mechanism that makes it possible to

Recently, microcomputers have become relatively easy to obtain, and they are now being considered as driving navigators for automobiles. One of these types of navigators is equipped with a direction sensor and a speed sensor, extracts the driving position of the car, plots the driving trajectory on a CRT display, for example, and maps a road map onto the display. A system is being developed that guides the course by having the plots extend along the roads on the map.

When employing this system, it is necessary to accurately detect the direction in which the vehicle is traveling using the direction sensor. For example, there are direction sensors that detect the earth's magnetic field to detect the angle between magnetic north and the direction of travel of the vehicle, but those that use earth's magnetic field cannot be used near the polar regions of the earth, and they cannot be used near the polar regions of the earth. There are drawbacks such as errors caused by changes. Therefore, some types of direction sensors detect changes in direction from a certain reference direction by sensing changes in air flow or pressure changes due to inertia of fluid due to changes in the direction of the vehicle body. things are done. When this type of direction sensor is used in an on-vehicle course guidance system, the reference direction is the direction of the vehicle when the vehicle is stopped. The direction in which the car is traveling is always determined as the cumulative result of angular changes from the reference direction when the car is stationary. In this case, if the vehicle stops frequently, the reference direction of the direction sensor will be reset and no problem will occur. However, if the car in question continues to drive for a long time without stopping, errors will occur in the detection of angle changes due to the drift of the direction sensor, and as these errors accumulate, the effects of these errors will be reduced. It grows and becomes impossible to ignore.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems by outputting a warning message after the vehicle has been continuously traveling for a certain period of time, thereby enabling the driver to take measures to offset the direction sensor. This will be explained below with reference to the drawings.

Fig. 1 is an overall perspective view of an embodiment of the course guidance system of the present invention as a unit, Fig. 2 is a block diagram of an embodiment of the invention, and Fig. 3 is position information stored in the trajectory memory shown in Fig. 2. 4A and 4B are explanatory diagrams illustrating the cumulative difference due to the drift of the direction sensor,
FIG. 5 shows the configuration of an embodiment of the offset warning mechanism according to the present invention.

In FIG. 1, 1 is a display screen of a cathode ray tube display, 2 is a shaded portion, 3 is a map printed on, for example, a transparent film, 4 is a map insertion guide groove, 5 is a map fixing means, and 6 is a traveling vehicle. It represents the trajectory.

As will be described later with reference to FIG. 2, a direction sensor and a speed sensor are mounted on the vehicle body to extract the momentary running position from the starting point, for example, and display the running trajectory 6 on the display screen 1 of the cathode ray tube display. Let's plot it. On the other hand, a map 3 printed on a transparent film is inserted from the bottom of the figure along the map insertion guide groove 4 so that the map is positioned in front of the display screen 1,
It is fixed by the fixing means 5 mentioned above. Needless to say, consideration has been given to displaying the traveling trajectory 6 in accordance with the scale of the map. Then, the traveling trajectory 6 is made to appear sequentially along the desired traveling route on the map, and the driver or the passenger knows the current traveling position from the correspondence between the traveling trajectory 6 and the map, and the driver or the passenger is able to know the current traveling position and proceed with the journey. The direction, current position, etc. are determined.

FIG. 2 shows an overall block diagram of one embodiment of the present invention. Reference numeral 7 in the figure is a direction sensor that detects the direction in which the vehicle is traveling in accordance with a certain reference direction. Reference numeral 8 denotes a speed sensor which generates clock pulses corresponding to, for example, the rotation of the wheels. Reference numeral 9 designates input keys, which are provided on the front surface of the shaded portion shown in FIG. 1 and on the side surface of the display body (not shown). Reference numeral 10 represents a display.

Direction information from the direction sensor 7 is converted into a digital signal by an A/D converter 11, and converted into angle information by an angle conversion section 12. On the other hand, the clock pulses from the speed sensor 8 are counted by a pulse counter 13 so that a sample clock can be output, for example, every 10 revolutions of the wheel. Every time the sample clock is issued, the angle information from the angle converter 12 is
The signal is supplied to the X component calculation section 15X and the Y component calculation section 15Y via the angle correction section 14. Then, the calculation unit 15X extracts the change on the X-axis based on the direction (north), for example, and adds it to the cumulative value of the change on the X-axis up to that point to calculate the current position coordinates on the X-axis, and the trajectory memory 16 The data is supplied to be stored in bank #0 (BANK). In addition, the calculation unit 15Y similarly extracts the change on the Y-axis, adds it to the cumulative value of the Y-axis change up to that point, calculates the current position coordinate on the Y-axis, and stores the coordinates in the #0 bank (BANK) of the trajectory memory 16. Supply to be stored in. That is, for example, when the coordinates at the start point are (0, 0), the coordinate values of the current position are calculated and supplied to the trajectory memory 16.

The contents of the trajectory memory 16 are read out in order to be transferred to the trajectory memory 18, and the memory conversion processing section 17
A predetermined conversion is performed in the locus memory 1.
It is stored on 8. In this case, conversion corresponding to the scale of the map is performed, which will be described later with reference to FIG. The contents of the locus memory 18 are read out to be transferred to the locus display memory 20, and are subjected to a predetermined transformation such as parallel movement in the memory conversion processing section 19, and then stored in the locus display memory 20. The contents of the trajectory display memory 20 are displayed on the display 10.
corresponds to the image figure displayed by the display drive circuit section 21,
The display 10 is supplied with the signal. That is, a traveling trajectory 6 as shown in FIG. 1 is obtained. The traveling trajectory 6 is observed through a map drawn on a transparent sheet shown in FIG. 1, and is matched with a desired road on the map to provide course guidance.

22 is a scale register in which scale information of the set map shown in FIG. The contents of the register 22 are supplied to the memory conversion processing section 17 and used when transcribing the contents of the trajectory memory 16 to the trajectory memory 18. Further, the contents of the register 22 are stored in the sampling interval determining section 23.
The information is notified to the memory address generator 24 and used for address generation by the memory address generator 24, and the processing during this time will be described later with reference to FIG.

Reference numeral 25 denotes a θ correction register, in which a correction value is set using the input key 9 to correct the angular deviation between the travel trajectory and the map when the vehicle is actually traveling on a road. Then, by using the correction value set in the adjustment mode, that is, the correction value set to correct the angular deviation in the adjustment mode such as when the unit shown in FIG. When transcribing to the trajectory memory 18, the above-mentioned angular deviation is corrected.

Reference numeral 26 denotes an X, Y, and θ correction register, which stores correction data in order to correct slight distortion between the road on the map and the travel trajectory 6 when the map is set as shown in FIG. is set via input key 9. Then, when the contents of the trajectory memory 18 are transferred to the trajectory display memory 20, the above distortion is corrected in the memory conversion processing section 19.

Reference numeral 27 is a parallel movement and/or rotation movement register, which is used to move the entire travel trajectory 6 on the display 10 in parallel or rotate it when the map 3 set as shown in FIG. 1 is replaced with a new map. In this case, movement amount information is set from the input key 9, and when the contents of the trajectory memory 18 are transferred to the trajectory display memory 20, the parallel movement and rotation are performed in the memory conversion processing section 19.

28 is a count value memory in which the contents of the pulse counter 13 are set at the time when the automobile passes, for example, a railroad crossing or a bridge, and are displayed on the display screen of the display 10 in a manner different from the above-mentioned travel trajectory 6. It is used to plot the above passing position. That is, a memory mark of a brighter point is left in the travel trajectory 6 and is used for alignment with the map. Further, 29 is a comparison processing section,
It is used to write a mark on the trajectory display memory 20 corresponding to a point corresponding to the contents of the counter value memory 28. Furthermore, 30 is an encoder that generates a code corresponding to input information from the input key 9.

Note that the display drive circuit 21 shown in FIG.
The suppress mode instruction information from the encoder 30 and the running information from the speed sensor 8 are received, and the display on the display 10 is suppressed while the car is running so that the display 1 is displayed while the driver is driving.
It has a display suppressing function to prevent undesired attention from being drawn to the display of 0.

The above-mentioned X component calculation section 15X, Y component calculation section 15
Regarding the main processes in Y, the trajectory memory 16, the memory conversion processing unit 17, and the trajectory memory 18, the third
This will be explained in detail with reference to the drawings.

As described above, the X-component calculation section 15X and the Y-component calculation section 15Y calculate the coordinates of the starting point, for example, (0,
0), the coordinates (xi, yi) of the vehicle running position at the time corresponding to each sample clock are calculated. This result is stored in the trajectory memory 16, and if this aspect is illustrated corresponding to the traveling trajectory 6, it can be considered as the one shown on the left side of FIG. 3A.
That is, from the coordinates (0, 0) of the starting point, (x _o-1 , y _o-1 ), ... (x ₂ , y ₂ ), (x ₁ , y ₁ ), (x ₀ ,
y ₀ ) is stored in the trajectory memory 16. The trajectory memory 16 includes, for example, #0 bank (BANK) for 128 words, and #1 bank to #5 for 64 words.
It has a bank. And the illustrated coordinates (x ₀ ,
128 coordinates starting from y ₀ ), i.e. (x ₁₂₇ , y ₁₂₇ )
are sequentially stored in the #0 bank using a push-down method, and the coordinate information overflowing from the #0 bank is extracted one in two and stored in the #1 bank using a push-down method. For example, the overflowing coordinate information is extracted one in two and stored in bank #2 in a push-down manner. The same holds true for storage in banks #3 to #5.

In other words, as shown in FIG. 3B, 128 pieces of coordinate information from the current point (x ₀ , y ₀ ) are stored in bank #0 for each sample clock, and the coordinate information for the current point (x 0 , y ₀ , y ₀ ) from the 129th to 256
Up to the first one, 64 pieces of coordinate information are stored in bank #1 every two sample clocks.
Similarly, from the 513th to the 1024th coordinate information, one piece of coordinate information is stored in bank #2 for 4 sample clocks for 64 pieces. Furthermore, bank #3 has one clock for every 8 sample clocks, bank #4 has one clock for every 16 sample clocks, and bank #5 has one clock for every 16 sample clocks.
One sample is stored in the bank for every 32 sample clocks.

When using a map as described above, display 1
The travel trajectory on 0 should be displayed in a form appropriate to the scale of the map. For this reason, when displaying the travel trajectory 6 corresponding to the map with the smallest scale ratio, the coordinate information on the #0 bank is sampled at an interval of "1" (sampling is performed as shown in FIG. 3C). without)
are sequentially read out to generate a travel trajectory consisting of 128 points. In addition, when using a map with approximately twice the scale, read the coordinate information for 64 pieces from the #0 bank at a sampling interval of "2" (extract every other piece).
Then, 64 pieces of coordinate information are read out from the #1 bank at a sampling interval of "1", and a travel trajectory consisting of a total of 128 points is generated. Similarly, for example, the scale factor is approximately 32
When using a double map, every 32 pieces from bank #0, every 16 pieces from bank #1, every 8 pieces from bank #2, every 4 pieces from bank #3, and every 2 pieces from bank #4. Read all from bank #5 one by one,
A travel trajectory consisting of a total of 128 points is generated.

When the contents of the trajectory memory 16 are transferred to the trajectory memory 18, scale information is set in the scale register 22 in accordance with the above-mentioned scale rate, and the above-mentioned sampling interval is determined accordingly. A memory address is generated. Then, the locus memory 16 is accessed based on the address. During this time, correction is performed based on the contents of the θ correction register 25 described above, but a detailed explanation thereof will be omitted in connection with FIG. 2. However, in extracting 128 points from the contents of the trajectory memory 16 and storing them in the trajectory memory 18, the memory conversion processing unit 17 converts the current coordinate The position is the origin (0, 0), and the previous coordinate position is (x ₁ −x ₀ ,
y ₁ −y ₀ ), and the previous coordinate position as (x ₂ −x ₀ , y ₂ −
y ₀ ), ... and store it in the trajectory memory 18.
Posted to. By doing so, when displaying on the display 10, it is possible to process the current position as a reference, and various adjustments can be made easily.

An in-vehicle course guidance system according to an embodiment of the present invention has the configuration and functions as described above, except that the direction sensor 7 determines the direction from which the vehicle is stopped based on the direction when the vehicle is stopped. When detecting the driving direction of a car by sensing angle changes, the longer the continuous driving time, the more errors in angle changes from the reference direction will accumulate, making it difficult to output correct results. become.

For example, as shown in FIG. 4A, the car has coordinates (X ₀ ,
Suppose that you are facing the direction of θ ₀ at the point Y ₀ ). Next, let d be the traveling distance before sampling the output from the direction sensor 7, and assume that there is an error α due to the drift of the direction sensor 7 every time you travel one section.
The direction θi at the nth point is observed as θi' as shown in FIG. 4B, and the X coordinate at the nth point is calculated as follows.

cosθ′=cos(θ+α)=cosθ・cosα−sinθ・sinα Here, α is extremely small, so cos(θ+α)≒cosθ−αsinθ Therefore, Similarly, The third term on the right side of the equations for X and Y above accumulates over time and becomes non-negligible when the car runs continuously for a long time. Therefore, although omitted in the explanation of FIG. 2, for example, if a configuration as shown in FIG. Output a message.

In FIG. 5, numerals 10 and 13 correspond to those in FIG. 2, 31 is a clock, 32 is a first counter for detecting whether or not the car is running, and 33 is a predetermined counter when the car is running. A second counter 34 that outputs a message output signal every time represents a message output processing section that outputs an offset warning message to the driver.

The first counter 32 performs counting using clock pulses sent from the clock 31, but if the car is running and the pulse counter 13 is activated and a sample clock signal is sent, it is reset and a new signal is sent. Start counting. Therefore, when the car is running, the output of the first counter 32 is never turned on. If the car stops and the output pulse from the pulse counter 13 does not arrive for a certain period of time, the first counter sends a reset signal to the second counter 33 due to overflow or the like. The second counter 33 similarly performs counting using clock pulses from the clock 31. If the car is stopped, it is reset by the reset signal from the first counter 32, but if the car continues to run for a predetermined period of time, the second counter 33 is reset.
causes an overflow or the like, and sends a message output signal to the message output processing section 34. The message output processing section 34 outputs a warning message on the display 10 that displays the driving trajectory, for example, to request offset of the direction sensor, and prompts the driver to take measures such as temporarily stopping the vehicle. The warning message may be stored in a voice memory or the like and outputted as voice if necessary.

As explained above, according to the present invention, it is possible to output a direction sensor offset warning message to the driver every time the vehicle is continuously driven for a certain period of time, thereby preventing the accumulation of errors due to direction sensor drift. Therefore, it is possible to prevent unexpected errors from occurring.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view of an embodiment of the course guidance system of the present invention as a unit, Fig. 2 is a block diagram of an embodiment of the invention, and Fig. 3 is position information stored in the trajectory memory shown in Fig. 2. FIGS. 4A and 4B are explanatory diagrams illustrating the cumulative error due to the drift of the direction sensor;
FIG. 5 shows the configuration of an embodiment of the offset warning mechanism according to the present invention. In the figure, 1 is a display screen, 22 is a shaded part, 3 is a map, 4 is a map insertion guide groove, 5
is a map fixing means, 6 is a travel trajectory, 7 is a direction sensor, 8 is a speed sensor, 9 is an input key, 10
is the display, 13 is the pulse counter, 1
6 and 18 are trajectory memories, 17 and 19 are memory conversion processing units, 20 is a trajectory display memory, 21 is a display drive circuit unit, 22 is a scale register, 23 is a sampling interval determination unit, 24 is an address generation unit, and 31 is a clock. , 32 and 33 are counters, and 34 is a message output processing section.

Claims (1)

[Claims] 1. A direction sensor and a speed sensor are mounted on the vehicle body to detect changes in the angle of the relative direction of travel, and the direction sensor and the speed sensor enable the vehicle to:
In an in-vehicle course guidance system configured to extract the location of the vehicle concerned and plot and display the extracted location of the vehicle on a display mounted in the vehicle in correspondence with a map, a counter that returns to its initial value when the vehicle is stopped, counts up or counts down at predetermined intervals while the vehicle is running, and sends out a message output signal when the count value reaches a predetermined value; The present invention further includes a message output processing unit that outputs an offset warning message for the direction sensor based on the output signal, and outputs a warning message to the effect that the direction sensor should be offset every time the vehicle continues to drive for a predetermined period of time. An in-vehicle course guidance system with an offset warning mechanism, characterized by: