JPH03230203A - Method and device for automatic steering of vehicle - Google Patents

Abstract

PURPOSE:To make the vehicle return to a set course smoothly by controlling the steering angle so that the vehicle travels in a direction obtained by subtracting an azimuth error from the output of an azimuth measuring means. CONSTITUTION:A subtracting means 6 which subtracts a correcting signal SC from the output signal Stheta from the azimuth measuring means 1 and supplies the subtraction signal Stheta-SC as a corrected azimuth signal Sthetac to an arithmetic means 5 is provided between the azimuth measuring means 1 and arithmetic means 5. Then when the vehicle passes a predetermined check point, the position shift from the course is detected to find the azimuth error, which is subtracted from the output signal of the azimuth measuring means 1. Further, the linear combination of the position deviation from the set course and the azimuth deviation obtained by correcting the azimuth error is used as the steering angle to control the traveling direction of the vehicle. Consequently, even if the vehicle deviates from the set course under the influence of the azimuth error, the vehicle can be made to return to the set course smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic steering method for quickly guiding a vehicle along a predetermined course, and an automatic steering device using the method.

[Conventional technology] Traditionally, this type of self-steering system was equipped with an automatic steering function.

In a vehicle such as a people carrier, there is a direction measuring means for detecting the traveling direction of the vehicle, a distance measuring means for measuring the traveling distance, a storage means for storing data of the set cost from the starting point to the target point, and these. The vehicle is equipped with control means and the like for processing measurement signals from the measurement means and controlling the steering of the vehicle so as to follow the set course. That is, the control means calculates the current position and traveling direction of the vehicle based on the azimuth signal outputted from the azimuth measuring means and the distance signal outputted from the distance measuring means, and furthermore, calculates the current position and traveling direction of the vehicle based on the azimuth signal outputted from the azimuth measuring means and the distance signal outputted from the distance measuring means. The vehicle is caused to travel along the set course by determining the deviation from the set course data and controlling the steering of the vehicle so that the deviation becomes zero.

However, in vehicles equipped with such an automatic steering function, measurement errors of the direction measuring means and distance measuring means themselves,
Rounding errors caused by calculations by the control means, as well as errors caused by dead zones in the vehicle's steering system, delays in actual steering relative to sliding from the control means, etc. accumulate, and gradually the result calculated by the control means differs from the actual set course. There is a problem in that the deviation error increases and the vehicle deviates from the set course.

Therefore, conventionally, in order to further correct the various errors mentioned above, when driving at a certain known point, the error between that point and the set course is detected and the error is reduced to zero. A correction means is employed to control the steering of the vehicle.

For example, as shown in FIG. 5, a vehicle that starts from a point P1 and is to travel along a set course S (a course from Pi→P2-P3) is traveling on a different course 5-(Pt→P-).
2), a certain specified driving point P2 is set as a checkpoint, and when the vehicle passes near the point P2, the position of the vehicle is measured by optical or magnetic measuring means, The distance deviation and azimuth deviation Δθ of the vehicle from checkpoint P2 are calculated. and,
The vehicle is controlled to return to the set course by steering the vehicle to travel from point P''2 toward the prescribed point P3 of the set course S so that the distance deviation becomes zero.

[Problems to be Solved by the Invention] However, in the conventional vehicle steering method equipped with such a correction function, when the direction measuring means itself has a measurement error, the point P′2 in FIG. Even if the steering is controlled so that the vehicle travels from point P3 to point P3, the problem arises that the vehicle travels to another erroneous point P-3, etc., making it difficult to perform accurate correction.

The present invention has been made in view of such problems,
It is an object of the present invention to provide an automatic steering method for a vehicle that smoothly returns the vehicle to a set course by accurately correcting the measurement error of an azimuth measuring means itself, and an automatic steering device using the method.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides an azimuth measuring means for detecting the traveling direction of the vehicle, a distance measuring means for measuring the distance traveled by the vehicle, and a direction measuring means for detecting the traveling direction of the vehicle, a distance measuring means for measuring the traveling distance of the vehicle, and a direction measuring means for detecting the traveling direction of the vehicle. a storage means for storing a set course up to the point; a detection means for measuring a positional deviation from the set course when the vehicle passes a predetermined checkpoint; and a direction measuring means based on the positional deviation and the distance traveled by the vehicle. The steering angle is controlled so that the vehicle travels in the direction obtained by subtracting the azimuth error from the output from the azimuth measuring means.

Further, the vehicle may be returned to the set course by controlling the traveling direction of the vehicle using a linear combination of the positional deviation from the set course and the azimuth deviation corrected for the azimuth error as the steering angle.

According to the present invention having such a configuration, when the vehicle passes a predetermined checkpoint, the positional deviation from the set course is detected to determine the orientation error, and the output signal from the orientation measurement means is detected. Since the azimuth error is subtracted from the azimuth error, the influence of the measurement error of the azimuth measuring means itself and the mounting error can be canceled out, and the vehicle can be reliably returned to the set course.

In addition, by controlling the vehicle's direction of travel by using a linear combination of the positional deviation from the set course and the azimuth deviation corrected for the azimuth error as the steering angle, even if the vehicle deviates from the set course due to the influence of the azimuth error, , it is possible to smoothly return to the set course.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 shows the configuration of an automatic steering system based on the steering method of the present invention. In FIG. 1, there is shown a direction measuring means 1 consisting of, for example, a tire wheel, which sequentially measures the running direction of the vehicle and outputs the direction signal Sθ, and a direction measuring means 1, which sequentially measures the running distance by, for example, measuring the number of rotations of the wheels, and outputs the direction signal Sθ. Sl
Distance measuring means 26 consisting of an output encoder etc., storage means 3 consisting of a random access memory (RAM) etc. for storing in advance data of a set course on which the vehicle should travel; The vehicle is provided with a detection means 4 for detecting this, and a calculation means 5 comprising, for example, a microprocessor or the like, for receiving output signals outputted from these means and calculating the direction in which the vehicle should travel.

However, between the direction measuring means 1 and the calculation means 5, the correction signal SC is subtracted from the output signal Sθ from the direction measurement means 1, and the subtracted signal Sθ-8C is used as the corrected direction signal SθC. A subtracting means 6 is provided for supplying the subtracting means 6 to

Note that the detection means 4 includes a light source provided on the vehicle side, and two reflectors provided at predetermined checkpoints.
A so-called triangular type device that measures the vehicle position by measuring the time it takes for the light emitted from the light source to return via these reflectors, or a device that uses multiple magnetic sensors on the vehicle side. A magnetic board is provided at the checkpoint, and a device or the like is applied that magnetically detects the position of the vehicle when the vehicle passes over the magnetic board.

Next, the operation of the automatic steering system of this embodiment having such a configuration will be explained.

First, to outline the operation of this embodiment, as shown in FIG. 2, there are roughly two control modes. That is, in this embodiment, the preset setting course includes:
Checkpoints P2. P3. P4. P5・
...Pn is provided. And step 100
When the vehicle is at the starting point, the direction measuring means 1
After initializing the output of the distance measuring means 2 to be zero, the output from the direction measuring means 2 is output along steps 1.10, 120.130 while driving between each checkpoint. On the other hand, when the vehicle passes near each checkpoint, steps 110 to 14 are performed.
After processing is performed to 130 via 0 and 150 to correct the azimuth signal from the azimuth measuring means 2, the steering of the vehicle is controlled based on the corrected azimuth signal.

First, a description will be given of the processing in steps 140, 150 to step 130 in FIG. 2, that is, the case where steering control is performed after correcting the measurement error of the azimuth measuring means 2 itself.

8 When the distance measuring means 2 measures that the vehicle has traveled the distance from the starting point PI, the detecting means 4 measures the actual position of the vehicle from the first check point P2, and calculates the position deviation from the check point. Measure the actual value. That is, if the positional deviation from the check point P2 (positional deviation from the set course) is D, then the measurement error (hereinafter referred to as azimuth error) Eθ that the azimuth measuring means 1 itself has is Eθ = jan-1 ( The calculation means 5 calculates it using the calculation formula: D/L)-(1).

Then, the calculation means 5 supplies the azimuth error Eθ as a correction signal SC to the subtraction means 6, and the subtraction means 6 subtracts the correction signal SC from the azimuth signal Sθ from the azimuth measurement means 1,
This subtraction result Sθ-5C is supplied to the calculation means 5 as a corrected azimuth signal SθC. By performing this processing, the corrected azimuth signal SθC indicates the true azimuth from which the azimuth error of the azimuth measuring means 2 itself has been removed.

Furthermore, the remaining checkpoint P3. P4...
For Pn, the above formula (
By performing the calculation of 1) and performing the above-mentioned subtraction processing, the corrected azimuth signal SθC for each checkpoint is sequentially calculated.

Then, based on this azimuth signal SθC and the measured distance deviation, the steering angle α is calculated by the process of step 130 (see the following equation (5)), which will be described later.

Next, the steering control in steps 120 to 130 (
The operation when the azimuth signal is not corrected will be explained.

In this process, as shown in FIG.
The movement of the vehicle 7 is assumed to be moving in the Y coordinate system, and the motion of the vehicle 7 is expressed by the following equation (2
) to (4).

dx/”dt=vacos (θ) ・----
-(2) dy/'dt=v*s in (θ)
・・・・・・(3) dθ/d t = (v/Lo)
Fist t a na α・=----(4) Here, dx/dt
is the change in unit time in the X direction, ayy"at is the change in unit time in the Y direction, ■ is the speed of the vehicle, LO is the distance between the front and rear wheels,
θ represents the azimuth of the vehicle measured by the azimuth measuring means 1, and α represents the advancing angle of the front wheels, that is, the steering angle. And the above formula (2),
After calculating the position of the vehicle from (3) as a point on the X'-Y coordinate system, the distance between that point and the set course is determined as the distance deviation.

In this embodiment, the steering angle of the wheels is set according to the steering angle α calculated by the calculating means 5, and when the vehicle deviates from the set course, the steering angle α is set to allow the vehicle to return to the set course. This is what we are trying to achieve.

For example, as shown in Fig. 4, when a positional deviation of D and an azimuth deviation of Δθ are detected from the vehicle's set course (assumed to be on the X-axis in the figure), the steering wheel to be controlled The angle α is determined by a linear combination of the positional deviation and the azimuth deviation Δθ according to the following equation (5).

α=1・D+2・Δθ (5) Here, the coefficients 1 and 2 are set to appropriate values in advance, and the azimuth deviation Δθ is determined when the vehicle reaches the predetermined checkpoint. When the vehicle is traveling between the two, there is a difference between the original orientation θ of the set course and the orientation signal Sθ output from the orientation measuring means 1 while the vehicle is actually traveling. When passing through, the value obtained by further subtracting the orientation error Eθ obtained by the above equation (1) (that is, θ−8θE
θ).

Next, the principle of returning the vehicle 7 to the set course by steering the front wheels of the vehicle 7 in the direction of the steering angle α determined by the calculation process of equation (5) above will be explained.

The setting course is now set to match the X axis.

Therefore, the positional deviation is the Y-axis value, and the azimuth deviation Δθ is θ
It can be equivalent to the above formula (3) % formula % (6) If θ is small, the above formula (6) becomes dD/dt=v・θ ・・・・・・(7
).

Further, assuming that the steering angle α is small, the above formula (4) % formula % (8) is obtained. Furthermore, by substituting the above equation (5) into the above equation (8), we get dθ/d t= (v/Lo)” (2 aθ for Kl ・D+)...(9), and further the above equation (9) when the vehicle speed V is constant (v=
const), the above equation (8
), then d2θ/dt2 = (v/'Lo) @ (K l * v-θ 2-
dθ/”dt)...(10) Since the above equation (1o) is a second-order differential equation, the conditions of K1 x 0 and K2 x 0 are satisfied for the coefficients 1 and 2. If it is set to a value of

Therefore, according to the size of the vehicle to be controlled, the optimum coefficient KF is set to 2 in advance, and the calculation means 5 in FIG. By performing calculation processing, it is possible to determine the optimal steering angle α, and by controlling the vehicle based on this steering angle α, it is possible to completely automate the return of the vehicle to the set course. It becomes possible.

In this embodiment, the calculation of the vehicle distance deviation (calculation in step 120) when the vehicle has not reached the checkpoint is performed using the following equation (11) instead of the above equations (2) and (3). , is calculated as the position in the XY coordinate system by applying the discretized difference calculation shown in (12). Then, the distance between the calculated position and the set course is defined as the distance deviation.

That is, if the current position is (Xn, Yn) and the previously determined position is (X n-1, Y n-1), the above formula (2)
Corresponding to (3), Xn = Xn-1+XΔt Xn-1+VXCO3(θ-Δθ)×Δt...
... (11) Yn = Ynl + Y△ t = Yn-1 + vXs in (θ - Δθ) × Δt...
...... Find it from (12).

[Effects of the Invention] As explained above, according to the present invention, when a vehicle passes a predetermined checkpoint, the positional deviation from the set course is laterally compared to obtain the orientation error, and the orientation measuring means Since the azimuth error is subtracted from the output signal from the azimuth measuring means, the influence of the measurement error of the azimuth measuring means itself and the mounting error can be canceled out, and the vehicle can be reliably returned to the set course. .

In addition, by controlling the vehicle's traveling direction using a linear combination of the positional deviation from the set course and the azimuth deviation corrected for the azimuth error as the steering angle, even if the vehicle deviates from the set course due to the influence of the azimuth error, You can smoothly return to the set course.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the steering angle control device according to the present invention, FIG. 2 is a flowchart for explaining the operation of the embodiment, and FIGS. FIG. 5 is an explanatory diagram for explaining the problems of the conventional technology. Reference numeral 1 in the figure; direction measuring means 2, distance measuring means 3, storage means 4; detection means; calculation means; subtraction means; vehicle

Claims (4)

[Claims] (1) Direction measuring means for detecting the direction of travel of the vehicle, distance measuring means for measuring the distance traveled by the vehicle, storage means for storing the set course from the starting point to the destination point, and predetermined checkpoints. A detection means for measuring a positional deviation from a set course when a vehicle passes, and a calculation means for calculating a bearing error of the bearing measuring means from the positional deviation and the travel distance of the vehicle, and an output from the bearing measuring means is provided. An automatic steering method for a vehicle characterized by controlling a steering angle so that the vehicle moves in a direction obtained by subtracting the azimuth error. (2) The vehicle is returned to the set course by controlling the steering angle of the vehicle using a linear combination of the positional deviation from the set course and the azimuth deviation corrected for the azimuth error as the steering angle. (1) Automatic steering method for a vehicle. (3) Direction measuring means for detecting the direction of travel of the vehicle, distance measuring means for measuring the distance traveled by the vehicle, storage means for storing the set course from the starting point to the destination point, and predetermined checkpoints. a detection means for measuring a positional deviation from a set course when a vehicle passes; a means for calculating a bearing error of a bearing measuring means from the positional deviation and a travel distance of the vehicle; and subtracting the bearing error from an output of the bearing measuring means. 1. An automatic steering device for a vehicle, comprising: arithmetic means for controlling a steering angle so that the vehicle moves in a direction obtained by the steering angle. (4) Direction measuring means for detecting the direction of travel of the vehicle, distance measuring means for measuring the distance traveled by the vehicle, storage means for storing the set course from the starting point to the destination point, and predetermined checkpoints. a detection means for measuring a positional deviation from a set course when a vehicle passes; a means for calculating a bearing error of a bearing measuring means from the positional deviation and a travel distance of the vehicle; and subtracting the bearing error from an output of the bearing measuring means. 1. An automatic steering system for a vehicle, comprising: arithmetic means for controlling the vehicle by using a linear combination of the azimuth deviation obtained by the above-mentioned position deviation as a steering angle.