JPS60201208A - Direction detector for vehicle - Google Patents

Abstract

PURPOSE:To prevent an error in advance direction even when the vehicle varies in slide angle by varying a set value which is switched to a detection direction based upon a steering angle when an error is caused in detection direction based upon the terrestrial magnetism according to the steering angle. CONSTITUTION:The 1st direction detector 10 which detects the advance direction of the vehicle generates digital signals of an X and a Y component corresponding to the advance direction of the vehicle. A distance sensor 20 which detects the run distance of the vehicle generates a distance pulse every time the vehicle advances by unit distance. A steering angle sensor 30 which detects the steering angle decide on the extent and direction of the direction change of the vehicle from the phase difference between outputs of two photocouplers. A microcomputer 40 performs arithmetic processing by receiving signals from the 1st direction detector 10, run distance sensor 20, and steering angle sensor 30 and a signal from a reader which detects and read map data on a specific area on a laser disk 51 stored with map data on plural areas.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a vehicular azimuth detecting device capable of accurately detecting the traveling azimuth of a vehicle regardless of whether the curve is steep or steep.

←) Conventional technology Recently, in vehicles such as cars, a map of the driving area is displayed in a position that is easy to see from the driver's seat, and the current position and driving trajectory of the own vehicle or the starting point and destination are displayed on the map. Devices have been proposed that provide route guidance for the driver's convenience, and are called map display devices or travel guidance devices. In order to know the current position of the own vehicle, such a device uses geomagnetism to detect the direction and travel distance.

By the way, on the ground, structures that contain reinforcing bars (iron bridges, buildings, etc.) and railway tracks and power transmission lines that carry large currents cause local geomagnetic disturbances (disturbances) inside tunnels. Ru. Therefore, when a vehicle equipped with a direction detection device passes through a place where there is such disturbance, the detected direction will be distorted due to the influence of the disturbance. Therefore, in order to eliminate the influence of such disturbances, for example,
Publication No. 3 states that the heading direction is detected by a steering angle sensor,
Based on the heading angle calculated based on the steering angle and geomagnetism.
A method has been proposed in which when the difference between the steering angle and the calculated heading angle exceeds a set value, it is assumed that a disturbance has mixed in with the earth's magnetic field, and the heading calculated from the steering angle is set as the heading direction of the vehicle.

Incidentally, when a vehicle travels around a curve, it often causes sideslip, and the sideslip angle varies depending on the number of passengers and the condition of the road surface, but such sideslip phenomenon causes errors in azimuth calculation from the steering angle to a greater or lesser degree. In general, there is a relationship between the sideslip angle β and the actual steering angle δ (proportional to the steering angle): β = δ. Here, K is a constant determined by many factors such as vehicle speed, vehicle weight, and vehicle wheel pace. From this, it can be seen that the sideslip angle increases as the steering angle increases, that is, as the curve becomes steeper. In other words, the above method of calculating the heading from the steering angle has a problem in that the error increases where the curve is steep.

(c) Purpose and structure of the invention The present invention has been made in view of the above points, and the difference between the heading calculated based on geomagnetism and the heading calculated based on the steering angle is greater than or equal to a set value. The purpose of the azimuth detection device, which switches the azimuth based on geomagnetism to the azimuth based on the steering angle, is to detect the accurate azimuth regardless of the steepness or steepness of the curve. The setting value for the difference in heading when switching is configured to be changed depending on the magnitude of the steering angle.

FIG. 1 shows an overall configuration diagram of the present invention, in which the traveling azimuth of the vehicle is calculated in the traveling azimuth calculating means from the azimuth data detected by the geomagnetic sensor and the travel distance data detected by the distance sensor, and the traveling azimuth of the vehicle is calculated based on the geomagnetic field. When the difference between the traveling azimuth calculated based on the steering angle and the traveling azimuth calculated based on the steering angle exceeds a set value, the traveling azimuth output is switched from the previous value based on geomagnetism to the value based on the steering angle. In this case, the set value for switching the heading output is changed by the set value control means depending on the magnitude of the steering angle.Examples The present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the basic configuration of the direction detecting device according to the present invention, in which 1 is a first direction detecting means that calculates the direction of travel of the vehicle by detecting the earth's magnetism, and 2 is a unit for calculating the direction of travel of the vehicle by detecting the earth's magnetic field. Distance detection means generates a pulse for each distance traveled, and numeral 3 denotes a steering angle detection means that detects the steering angle of the vehicle. Reference numeral 4 denotes a device for calculating the accurate traveling direction of the vehicle by performing various calculation processes based on the signals from the first direction detecting means 1, the distance detecting means 2, and the steering angle detecting means 3. The second azimuth detection means 5 calculates the traveling direction of the vehicle using the steering angle information from the steering angle detection means 3, and the azimuth detected by the first azimuth detection means 1 and the second azimuth detection means. When the difference from the azimuth detected by 5 exceeds a set value, the azimuth from the second azimuth detection means 5 is output, and when the difference is less than the set value, the azimuth from the first azimuth detection means 1 is output. and a set value switching means 7 which changes the set value obtained by the second azimuth detection gP sensor 5 and changes it accordingly. The structure is Q. The second azimuth detection means 5 includes an azimuth change calculation device 51 that calculates a change in azimuth based on the steering angle information from the steering angle detection means 3, and a heading azimuth calculation device 52 that calculates a heading. be done.

FIG. 3 shows an embodiment of a map display device using the direction detection device according to the present invention.

In the figure, reference numeral 10 denotes a first direction detection device for detecting the traveling direction of the vehicle; It is equipped with an amplifier 12 for amplifying an output signal and an A/D converter 13 for A/D converting the amplified signal, and generates digital signals of ix and yta according to the traveling direction of the vehicle.

A distance sensor 20 detects the travel distance of the vehicle, and generates a distance pulse every time the vehicle travels a unit distance.

A steering angle sensor 30 detects the steering angle, and is connected to a rotary plate 31 with a slit that rotates in accordance with the rotation of the steering wheel and two photocouplers 32a to 32b.

Photocoupler 32g as the steering wheel rotates
, 32b outputs the steering signal 8Tt -ST
x is a rectangular wave as shown in Fig. 4 (←) when the steering wheel rotates in the forward direction, and as shown in Fig. 4 (b) when the steering wheel rotates in the reverse direction. The magnitude of the direction change of the vehicle, that is, the steepness and steepness of the curve of the road on which the vehicle is traveling, as well as the direction of rotation, can be determined from the phase difference between the outputs of the two photocouplers.

40 is a microcomputer that executes digital arithmetic processing according to a predetermined control program;
41, a ROM 42, a RAM 43, an interface circuit 44, and a CRT controller 4-245.
It becomes operational when supplied with power source voltage from the on-board battery. This microcomputer is the first direction detecting device l.
A laser disk serving as an external memory that stores digital signals of the X and Y components of geomagnetism from O, distance pulses from the mileage sensor 20, rectangular wave signals from the steering angle sensor 30, and map data of a plurality of regions. It receives signals from a reading device 50 that detects and reads map data of a specific area within 51, performs arithmetic processing, and outputs a display signal from a CRT controller 45 for displaying a map and various travel route information. Map data, travel routes, characters, etc. are displayed on a CRT display device 60 using a video signal and a synchronization signal from the CRT controller 45.

Next, the operation of the map display device having the above configuration will be explained based on a flowchart of a control program.

FIG. 5 is a flowchart of the main processing.

In the vehicle configured as shown in FIG. 3, when the key switch is turned on at the start of operation, power supply voltage is supplied from the vehicle battery and the various electrical systems are put into operation. In the microcomputer 40, the arithmetic processing is started from the start step (400) in FIG. Set to the initial state.

After this initial setting, in checking the function keys, that is, map switching and other various operation keys (402), the manual reading of the keys and corresponding processing 2 are performed. Step (
Step 403) determines whether it is necessary to read map data, and if new map data is required, the next step (403) is performed.
04), the map data is read. If unnecessary, the process directly moves to step (405). Step (4
In step 05), the position display is rewritten based on the position data calculated in the interrupt process, and then step (402
) Return to This routine is then repeated.

While this main routine is being executed repeatedly, when a distance pulse from the mileage sensor 20 is input to the interrupt terminal of the microcomputer 40, the microcomputer 40 temporarily suspends the arithmetic processing of the main routine.
The interrupt processing shown in the figure is carried out one by one.In this interrupt processing, as will be described later, while the main routine is being repeated, the steering ring signal 8Tt from the steering angle sensor 30 is When input to the interrupt terminal of the microcomputer 40, the microcomputer 40 temporarily suspends main processing and executes the interrupt processing shown in FIG.

Next, returning to FIG. 6, we will explain the interrupt processing by the distance pulse from the distance sensor 20. When the interrupt of the O distance pulse occurs, calculation starts from the interrupt processing step (500), and in step (sol), the first Direction detection device 1
0, the earth's magnetism is detected and the azimuth signal X1*Yl converted into a digital signal is manually input. Azimuth calculation step (
1ian-
In step (503), the count value Na(1) of the pulse output from the steering angle sensor 30 and the vehicle-specific constant Cs (
The azimuth change Δ'5(1) can be calculated by multiplying by Δ'5(1), which indicates how much one pulse from the steering angle sensor actually changes the direction of the vehicle.

In step (504), the initial value θm(d
Based on the azimuth change Δθ5(1), the vehicle's traveling direction θ1(
υ=θ, (10 fathoms). Δθ, (calculate ri. However, θ,
Since (I) causes errors depending on the road surface condition, the initial value is reset at regular intervals to prevent accumulation of errors.

In step (so5), the conventional set value θ is a constant value, but in the present invention, the set value θ1 is changed in accordance with changes in the steering angle. In this example, the set value θ is the term 1ΔθB(1) l X due to the change in azimuth angle.
Calculate as the sum of c* and constant 03. This is a constant that is appropriately selected depending on the size of the peri-angle that crosses C2. C3 is a constant that guarantees the minimum value of the set value 0v, and corresponds to the steering play.

Steps (506, 50, so8) are steps for detecting and removing disturbances, in which the azimuth angle θ□(0) determined by detecting the earth's magnetic field and the azimuth angle θm(1) determined from the steering
Calculate the difference 1θ, (0-0m(111), and if the difference is larger than the set value θ,'f!-, it is assumed that a disturbance has mixed in the geomagnetic field, and the azimuth angle θm (ll is cut, and the azimuth angle is θ, (
0 is used as the current direction for distance calculation in subsequent steps.

Step (509) executes distance calculation using the azimuth angle θ (-0g(1)) from which the disturbance was removed in step (508). In other words, if t is a unit distance, the distance III traveled in the X and Y directions is t-龜θ, t・(2)θ, and the current position of the vehicle is the distance 1iJiDX, DY at the time one pulse ago.
You can make it by adding each. This completes the interrupt process when a distance pulse is received from the distance sensor 20, and returns to the main process (shown in FIG. 5) from step (510).

Next, interrupt processing when the steering STI is input will be explained with reference to FIG.

Steering signal ST1 output from steering angle sensor 30
e STg Fi Since the relationship is as shown in FIG. 4, it is possible to determine whether the steering wheel has rotated forward or reverse by determining the level of the steering signal STz when the steering signal 8Ts rises. Furthermore, by counting the number of times the steering signal ST1 is interrupted, the magnitude of the rotation of the steering wheel can be determined.

In step (602), the steering signal 5T20
As a result of level judgment, signal ST: is at Low level (・
If the steering wheel is in normal rotation, step (60
In 3), l is added to the count number N. Hi again
If the steering wheel is at the gh level (steering is in reverse), 1 is subtracted from N in step (604). This completes the steering signal ST1 interrupt processing, and returns to the main processing shown in FIG. 5 from step (605). By repeating this process when the steering signal STs rises, the steering state can be determined.

In the above embodiment, the direction is detected and the distance is calculated every distance 1llII<rus from the distance sensor, but the direction may be detected every unit time regardless of the distance pulse.

(e) Detailed Description of the Invention As described in detail, the present invention provides a direction detection device that switches from a traveling direction based on geomagnetism to a detection direction based on a steering angle when an error occurs in a detected direction based on geomagnetism. Since the setting value for switching to the heading direction is changed according to the size of the steering angle, errors in the heading direction based on the steering angle can be prevented even if the vehicle's sideslip angle changes depending on the number of soldiers from the East or the steepness or steepness of the curve. When used in map display devices and travel guidance devices, it is possible to accurately display travel trajectories and route guidance, thereby improving performance. In addition, in order to accurately detect the direction from the steering angle, it is necessary to add a force measurement sensor and a road surface μ measurement sensor, but in reality it is difficult to accurately measure the road surface μ. However, according to the present invention, the direction can be accurately detected from the steering angle and the calculation time can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a direction detecting device according to the present invention, FIG. 2 is a block diagram showing the basic structure of an embodiment of the direction detecting device according to the present invention, and FIG. 3 is a block diagram showing the basic structure of an embodiment of the direction detecting device according to the present invention. A schematic diagram showing the course of one embodiment of the detection device, FIG. 4 is an output signal waveform diagram of the steering angle sensor of the azimuth detection device shown in FIG. 3, and FIG. The main processing flowchart of the operation of the travel guidance device,
FIGS. 6i and 7 are flowcharts of interrupt processing for azimuth calculation in the present invention. 1... First direction detection means, 2... Distance detection means, 3
...Steering angle detection means, 5...Second direction detection means, 6
...Disturbance detection and removal means, film constant value switching means for 7, 31.
...Rotary plate with slit, 32a*32b...Photocoupler

Claims (1)

[Claims] The difference between the vehicle's traveling azimuth calculated based on the earth's magnetic field and the vehicle's traveling azimuth calculated based on the steering angle is the set value tool F.
In a direction detection device that outputs a heading angle based on geomagnetism when φ exceeds the set value, switches to output a heading angle based on the steering angle when 1. A vehicle orientation detection device characterized in that it is provided with a setting value switching means for switching according to the setting value.