JPS6261275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-vehicle course guidance system with an automatic direction adjustment 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 car using a direction sensor and a speed sensor mounted on the car body, plots it on the display, and guides the driving course by correlating it with the map. In order to reduce the influence of the cumulative error caused by the drift of the direction sensor, when the vehicle is confirmed to have stopped and there is no change in direction, the output of the direction sensor is automatically extracted and the output from the direction sensor is automatically extracted. The present invention relates to a vehicle-mounted course guidance system with an automatic direction adjustment mechanism that offsets the output so that the output does not indicate a change in direction.

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 adopting this system, it is conceivable to use a direction sensor that utilizes geomagnetism, for example, to determine the traveling direction of the vehicle based on magnetic north. However, when using geomagnetism, there are problems such as it cannot be used near the Earth's polar regions and errors may occur due to local changes in the magnetic field. Therefore, consideration has been given to using a direction sensor that detects, for example, a change in airflow or a change in pressure due to the inertia of a fluid, and outputs a change in the traveling direction of the vehicle. When such a direction sensor is used, the traveling direction of the vehicle is not determined as an absolute value, but as a relative value based on an angular change from the traveling direction at a certain point in time. Therefore, when the vehicle continues to run for a long time, an accumulated error occurs due to the drift of the direction sensor, and its influence cannot be ignored.

Although the present invention is not limited to the use of the direction sensor having the above-mentioned special configuration, it focuses on the fact that there is no change in direction when the car is stopped, and it is possible to confirm that the car is stopped while driving. The purpose of this invention is to automatically offset the output of the direction sensor in a state where there is no change in direction, thereby reducing the influence of cumulative errors caused by the drift of 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. FIG. 4 is an explanatory diagram illustrating the storage mode and readout mode, FIG. 4 is an example configuration of an automatic direction adjustment mechanism that is partially omitted from FIG. 2, FIG. 5 is an explanatory diagram of an embodiment of a pulse determination circuit,
FIG. 6 shows an explanatory diagram of the operation of one embodiment of the offset correction circuit.

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 trajectory 6 in accordance with the scale of the map. and,
The travel trajectory 6 is made to appear sequentially along the desired travel route on the map, and the driver or passenger knows the current travel position based on the correspondence between the travel trajectory 6 and the map, and determines the direction of travel. The 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 and the side surface of the display body shown in FIG. 1. 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 it in #bank (BANK) of the trajectory memory 16. Supply to store. 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
The route is observed through a map written on a transparent sheet shown in FIG. 1, and the course is guided by matching the desired road on the map.

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 is used to correct slight distortions between the road on the map and the travel trajectory 6 when the map is set as shown in FIG. Data 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. Reference numeral 29 denotes a comparison processing section, which is used to write marks on the locus display memory 20 corresponding to points corresponding to the contents of the count 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. Trajectory memory 16
For example, #0 bank (BANK) for 128 words,
It has #1 bank to #5 bank of 64 words. Then, the 128 coordinates (x ₁₂₇ , y ₁₂₇ ) starting from the illustrated coordinates (x ₀ , y ₀ ) are sequentially stored in the #0 bank using, for example, a push-down method.
For example, the coordinate information overflowing from the #0 bank is extracted every second and stored in the #1 bank in a push-down manner, and the coordinate information overflowing from the #1 bank is extracted every second, for example. The data is stored in bank #2 using push-down method. #3 below
The same applies to storage in banks to bank #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.

The in-vehicle course guidance system according to one embodiment of the present invention has the configuration and functions described above, but in order to reduce the influence of cumulative errors caused by the drift of the direction sensor 7, Adjustment of the output of sensor 7 is required. The present invention adjusts the output from the direction sensor 7 using an automatic direction adjustment mechanism as shown in FIG.

In FIG. 4, symbols 7, 8, 11, 12, and 13 correspond to those in FIG. 2, 31 is an offset correction circuit, and 32 is an offset correction circuit.
represents a pulse determination circuit. As described above, the direction information output from the direction sensor 7 is converted into a digital signal by the A/D converter 11, and converted into angle information by the angle conversion section 12. When the car is stopped, there is no change in direction, so A/
The output of the D converter 11 is sent to the direction sensor 7 and the A/
If there is an offset of the D converter 11, it corresponds to that offset. On the other hand, if the car is running, the speed sensor 8 emits a pulse, and this pulse is input to the pulse determination circuit 32. For example, the pulse determination circuit 32
It is configured as shown in the figure and determines whether the output pulse from the speed sensor 8 arrives within a predetermined period. That is, in FIG. 5, counter 34 continues to count by clock pulses from clock 33, but is reset by output pulses from speed sensor 8.
Therefore, when the car is running, there is no output, and when the car is stopped, an overflow occurs to the offset correction circuit 31.

The offset correction circuit 31 operates as shown in FIG. 6, for example. First, as in process a shown in FIG. 6, the presence or absence of an output from the pulse determination circuit 32 is checked, and if there is no output, nothing is done because the car is running. If there is an output, it means that the car has stopped, so as shown in process b shown in FIG. Check. If a change in direction is detected even though the vehicle is stopped, this means that an error has occurred in the direction sensor 7 due to drift, so the A/D converter 11 is The output is corrected and adjusted so that the output of the angle converter 12 indicates no change in direction. In this way, it is possible to automatically adjust the direction when the vehicle is stopped.

As described above, according to the present invention, it is possible to automatically offset the output of the direction sensor when the vehicle stops, thereby reducing the influence of cumulative errors caused by drift of the direction sensor. In particular, it detects changes in air flow and pressure changes due to fluid inertia,
When using a direction sensor that outputs a change in the direction of travel of the vehicle, that is, when the vehicle stops,
This effect is significant when using a direction sensor that causes drift due to its inertial force.

[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. 4 is an explanatory diagram illustrating the storage mode and readout mode, FIG. 4 is an explanatory diagram of an embodiment of the automatic direction adjustment mechanism according to the present invention, FIG. 5 is an explanatory diagram of an embodiment of the pulse determination circuit, and FIG. 6 is an offset diagram. An explanatory diagram of one embodiment of the operation of the correction circuit is shown. In the figure, 1 is a display screen, 2 is a shaded part, 3 is a map, 4 is a map insertion guide groove, 5 is a map fixing means, 6 is a traveling trajectory, 7 is a direction sensor,
8 is a speed sensor, 9 is an input key, 10 is a display, 13 is a pulse counter, 16,1
8 is a trajectory memory, 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 a memory address generation unit, and 26 is an X , Y, θ correction registers, 31 represents an offset correction circuit, and 32 represents a pulse determination circuit.

Claims (1)

[Scope of Claims] 1. A direction sensor and a speed sensor are mounted on the vehicle body to detect relative changes in the angle of the traveling direction, and a display mounted on the vehicle body and a display screen of the display are displayed. an in-vehicle course configured to extract the location of the vehicle body using the direction sensor and the speed sensor, plot the location on the display, and associate it with the map; In the guidance system, an angle conversion unit converts the output from the direction sensor into angle information corresponding to a direction change of the vehicle body, and a signal is provided to detect a state when an output pulse from the speed sensor is not present for a predetermined period of time. and an offset correction circuit that corrects the output from the direction sensor based on the output of the pulse judgment circuit so that the output of the conversion result in the angle conversion section indicates no change in direction, An in-vehicle course guidance system with an automatic direction adjustment mechanism, characterized in that the output of the direction sensor is automatically offset when the vehicle stops so as to reduce the influence of accumulated errors due to sensor drift.