JP2917644B2 - Autopilot control device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering control device for a vehicle, and more particularly to the control of an automatic steering control device for automatically driving a vehicle along a predetermined guideway.

[0002]

2. Description of the Related Art Autopilot vehicles that automatically travel on a predetermined lane are well known, and are used in automatic guided vehicles in factories and in endurance running tests. Such an autopilot vehicle has, for example, a guide cable provided on a track, and operates a steering wheel, an accelerator, a brake, and the like with an actuator while detecting a position of the guide cable by a magnetic field sensor provided in the vehicle, and moves along the guide cable. This realizes automatic traveling, whereby the vehicle can be made to travel faithfully on the course.

[0003] Conventionally, Japanese Patent Laid-Open No. 63-33
As disclosed in Japanese Patent Publication No. 15, there is a vehicle in which an actual course is run by manned operation to collect course information and information necessary for setting a running course is given to a vehicle in advance. According to this, even on relatively complicated terrain, it is possible to run smoothly without departing from a predetermined course.

However, in such conventional vehicle automatic driving, since the vehicle is driven by a program created mechanically, a fine-grained driving that a human can actually drive cannot be performed, and the riding comfort is poor. There was a problem of bad.

In general, the most important problem in an autopilot is to drive the vehicle faithfully on a course. Therefore, high-speed control with a high feedback gain is performed. There was a problem that stability was deteriorated. Therefore, the applicant of the present application has previously proposed the following vehicle autopilot control device in Japanese Patent Application Laid-Open No. 2-231609. That is, first, the driver actually travels on the taxiway, and the taxiway is taught as a target course, and the operation amounts of various actuators at the time of this teaching are detected and stored in the storage means together with the target course. And
When the vehicle is controlled to travel according to the teaching content, a prediction error when the vehicle travels a predetermined distance from the current position is sequentially calculated, the teaching content is corrected according to the prediction error, and the operation amounts of various actuators are calculated. is there.

[0006]

However, the running conditions when the driver actually runs and teaches the target course and the running conditions when the vehicle automatically runs along the target course according to the teaching contents are the friction coefficients of the road surface. If the speed varies depending on changes in μ and vehicle speed, there is a problem that it is not always possible to run accurately on the target course.

That is, if the friction coefficient μ and the vehicle speed of the road surface are different from the values at the time of teaching due to the degree of wetness of the road surface, the front and rear wheel cornering forces and the motion characteristics of the vehicle change, and the steering characteristics of the vehicle change. Even if the vehicle is controlled with the same amount of steering, the turning radius of the vehicle differs from that at the time of teaching, causing a course deviation.

Further, for example, in a durable running test, it is necessary to run not only one vehicle type but also various types of vehicles along a target course. There is complication that the teaching operation must be performed by the vehicle type.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an automatic steering control device for a vehicle capable of accurately traveling on a target course in accordance with various traveling conditions and vehicle types. Is to provide.

[0010]

In order to achieve the above object, the present invention relates to an automatic steering control device for a vehicle which controls each actuator for automatic steering based on a current position of the vehicle with respect to a target course. Vehicle speed detecting means for detecting the speed of the vehicle, steering amount detecting means for detecting the steering amount of the vehicle, yaw rate detecting means for detecting the yaw rate of the vehicle, and turning radius calculation for calculating the turning radius of the vehicle from the vehicle speed and the yaw rate Means, a model calculating means for sequentially calculating a correspondence between the steering amount and the turning radius within a predetermined time, and a steering required by using the correspondence from a target turning radius required for traveling on the target course. A steering amount calculating means for calculating the amount.

[0011]

As described above, if the same steering amount is given under different driving conditions or vehicle types, the turning radius is different, so that the target course cannot be run. However, in the present invention, the turning radius required to run on the target course is not obtained. Is input, and the steering amount necessary to obtain this turning radius is automatically calculated to control traveling.

Although the correspondence between the steering amount and the turning radius differs depending on the running conditions or the type of vehicle, the correspondence between the steering amount and the turning radius within a predetermined time is statistically processed to calculate a model. By sequentially obtaining the steering amount corresponding to the required turning radius using the correspondence relationship between the turning radius and the steering amount, the vehicle can be controlled with the steering amount corresponding to the traveling condition or the vehicle type.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an automatic steering control device for a vehicle according to the present invention.

FIG. 2 shows the configuration of this embodiment.
Front magnetic field sensor 110 for detecting lateral deviation of a vehicle
a, front lateral deviation detection circuit 111a, rear magnetic field sensor 11
0b, a rear lateral deviation detection circuit 111b is provided, which detects a magnetic field output from the induction cable 20 provided on the taxiway to determine the lateral deviation of the vehicle and the yaw angle. That is, the front lateral deviation is Yf, and the rear lateral deviation is Y
Assuming that r, the lateral deviation Y of the vehicle 28 is Y = (Yf + Yr) / 2, and if the total length of the vehicle 28 is a, the yaw angle θ of the vehicle is θ = (Yf−Yr) / a. .

A magnet pickup 114 for determining the vehicle speed is provided, and the vehicle speed is detected by detecting the number of rotations of the magnet rotating plate 113.

An antenna 115 and a reference position detection circuit 116 for detecting the position of the vehicle on the taxiway are provided.
The antenna 115 receives an electric wave output from the position beacon 22 provided at each predetermined point on the taxiway and supplies the electric wave to the reference position detection circuit 116, thereby detecting the reference position on the course.

An arithmetic processing circuit ECU 24 for inputting detection signals from the above-mentioned various sensors and performing arithmetic processing, and a feedback processing circuit 26 for performing predetermined processing by feeding back operation amounts of various actuators for operating the vehicle.
Is provided to control the steering 30 of the vehicle.

FIG. 1 shows an arithmetic processing circuit E in this embodiment.
A schematic diagram showing the principle of processing performed by the CU 24 and the feedback processing circuit 26 is shown. Time-series target lateral deviation l ^* (t) required to travel on the target course,
The yaw angle θ ^* (t) is input, and a feedback control amount Δu for eliminating the error based on the error between the target value and the current vehicle position l (t), θ (t) is sent to the feedback controller. Is calculated and output. Then, the actual vehicle to be controlled is steered at the steering angle δ in accordance with the feedback control amount Δu. The vehicle shows a turning radius according to the running conditions and steering characteristics at that time, and runs at a turning curvature ρ which is the reciprocal of the turning radius. This steering amount δ
And the turning curvature ρ depend on running conditions and vehicle type. Accordingly, the arithmetic processing circuit ECU 24 models the relationship between the steering amount δ and the turning curvature ρ at the predetermined time Δt as ρ = f (δ), and stores the model in the memory.

This model is a model corresponding to the traveling condition and the vehicle type at Δt, and means that when a steering amount δ is given, the turning curvature ρ according to the traveling condition and the vehicle type at that time is uniquely determined. Conversely, if the turning curvature ρ is given, it means that the steering amount δ necessary to output the turning curvature ρ is uniquely determined.

Therefore, an inverse model (inverse operation) of this model
Δ = f ⁻¹ (ρ) is calculated and stored in the memory again.
When the target turning curvature [rho ^* is given necessary for traveling the target course, by using the inverse model the target turning curvature [rho ^* steering amount necessary for outputting [delta] ^* is calculated, the foregoing feedback It is added to the control amount Δu and output to the actuator. The above procedure, that is, the correspondence between the steering amount δ and the turning curvature ρ is calculated as a model ρ = f (δ), and the target turning curvature ρ ^* given by using the inverse model δ = f ⁻¹ (ρ) ^. By sequentially repeating the procedure for calculating the required steering amount δ ^* from the actuator, an appropriate steering amount according to the traveling conditions is given to the actuator, and the vehicle can travel accurately on the target course.

FIG. 3 shows a more specific configuration diagram of this embodiment, and FIG. 4 shows a flowchart of this embodiment. In FIG. 4, when the steering control is started, first, a lateral deviation error Δl = l ^* −1, a yaw angle error Δθ = θ ^* −θ, and a yaw rate ω of the vehicle are detected. Here, l ^* and θ ^* are the target lateral deviation and the yaw angle corresponding to the course shape of the target course input to the arithmetic processing circuit ECU 24 by input means (not shown). For example, both are set to 0 at the initial position. Can be performed (S101).

Next, a mathematical model indicating the correspondence between the steering amount δ and the turning curvature ρ is identified (S102). Hereinafter, a method for obtaining this model will be described. First, this model is described by the following mathematical formula.

Ρ (k) + a ₁ ρ (k−1) + a ₂ ρ (k−2) = b ₁ δ (k−1) + b ₂ δ (k−2) ρ (k) = ω (k) / V (k) where k is a parameter representing the traveling distance. It is assumed that δ (1), δ
(2),..., Δ (N−1) and ρ (1), ρ (2),.
.., Ρ (N) is obtained. By determining a ₁ , a ₂ b ₁ , and b ₂ in the above equation based on these time-series data, a model of the correspondence can be obtained. Substituting these data into the above equation gives ρ (3) = − a ₁ ρ (2) −a ₂ ρ (1) + b ₁ δ (2) + b ₂ δ (1) ρ (4) = − a ₁ ρ (3) −a ₂ ρ (2) + b ₁ δ (3) + b ₂ δ (2)... Ρ (N) = − a ₁ ρ (N−1) −a ₂ ρ (N−2) + b ₁ δ _{(N-1) + b 2} δ (N-2) of N-2 pieces of recurrence formula will be obtained. Then, from these N-2 recurrence formulas, a ₁ , a
₂ , b ₁ and b ₂ may be determined.

When these N-2 recurrence expressions are represented by a matrix,

(Equation 1) When this is expressed as ρ _N = Φ _N a, when the estimated value a _{N of a is obtained} by the least square method, a _N = (Φ _N ^T Φ _N ) ^-1 Φ _N ^T ρ _N and a ₁ , A ₂ , b ₁ , and b ₂ can be obtained. A ₁ , a ₂ , b
₁ and b ₂ are stored in the memory.

After the correspondence between the steering amount δ and the turning curvature ρ is calculated as a model ρ = f (δ), the steering amount δ ^* required to travel on the target course is calculated using this model in reverse. (S103). The steering amount δ ^* calculation process specifically means the following contents.

In the model ρ (k) + a ₁ ρ (k−1) + a ₂ ρ (k−2) = b ₁ δ (k−1) + b ₂ δ (k−2), let k = 3 and solve for δ. Δ (2) = (ρ (3) + a ₁ ρ (2) + a ₂ ρ (1) −b ₂ δ (1)) / b ₁ Assuming that the current time is t ₁ (k = 1), δ
(1) and ρ (1) are the current steering amount and the turning curvature. At this time, δ (2) is the steering amount to be input in the next control cycle t ₂ , and ρ (2) is the target turning curvature at that time. Further, ρ (3) is the target turning curvature in the control cycle of the next t ₃ . Therefore, by giving the current steering amount δ (1), the turning curvature ρ (1), and the future target turning curvatures ρ (2), ρ (3) for a time corresponding to two control cycles, the next control cycle can be performed. The steering amount δ (2) to be output is obtained.

After the steering amount δ ^* corresponding to the target turning curvature ρ ^* is calculated by using the inverse model in this manner, feedback for eliminating the current vehicle lateral deviation error Δl and the yaw angle error Δθ. The control amount Δu is calculated (S10
4). Here, when the current lateral deviation of the vehicle is away from the target value by Δl and the yaw angle is separated by Δθ, a new error of L · Δθ occurs a predetermined distance Lm ahead, and therefore, The prediction error Lm ahead is Δl−L · Δθ. In order to eliminate this prediction error, given on the prediction error to a feedback correction quantity Δu is multiplied by a gain K _p, an actuator operation amount is added to the calculated steering amount [delta] ^* at step S103 described above Output (S105).

After a predetermined time Δt has elapsed, the model ρ is obtained again from the time series data of the steering amount δ and the turning curvature ρ.
f (δ) is calculated (if the running conditions at this time are different from the previous running conditions, the model type f will be different), and the previous model is updated in real time to correspond to the target turning curvature. The calculated steering amount δ ^* is calculated.

The target turning curvature ρ ^* (target turning radius)
Can be calculated in advance from the shape of the track to be traveled and given as a function of position or time.

As described above, in the present embodiment, the correspondence between the steering amount and the turning curvature is calculated as a model based on the time series data of the steering amount and the turning curvature within a predetermined time, and the target turning is calculated using this model. This is to calculate the amount of steering required to obtain the curvature, and there is no need for the driver to actually drive and teach the target course, and because the model is updated sequentially, it is extremely suitable for the driving conditions or vehicle type. It becomes possible to perform the traveling control with good adaptability.

In particular, in the present embodiment, a dynamic model that is sequentially updated as the correspondence between the steering amount and the turning curvature is used, so that it is more resistant to disturbance and noise than a case where a static model is used. Stable control becomes possible.

[0032]

As described above, according to the automatic pilot control device for a vehicle according to the present invention, it is not necessary to perform the teaching operation, and the vehicle can accurately travel on the target course without depending on the traveling conditions and the vehicle type. It becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a control principle according to an embodiment of the present invention.

FIG. 2 is an overall configuration block diagram of the embodiment.

FIG. 3 is a control configuration block diagram in the embodiment.

FIG. 4 is a control flowchart in the embodiment.

[Explanation of symbols]

 Reference Signs List 20 guide cable 22 position beacon 24 arithmetic processing circuit ECU 26 feedback processing circuit 28 vehicle

Claims (1)

(57) [Claims] 1. A vehicle automatic steering control device for operating and controlling each actuator for automatic steering based on a current position of a vehicle with respect to a target course, a vehicle speed detecting means for detecting a speed of the vehicle, and a steering amount of the vehicle. A yaw rate detecting means for detecting a yaw rate of the vehicle, a turning radius calculating means for calculating a turning radius of the vehicle from the vehicle speed and the yaw rate, and the steering amount and the turning radius within a predetermined time. Model calculation means for sequentially calculating the correspondence relationship between the two, and steering amount calculation means for calculating a necessary steering amount using the correspondence relationship from a target turning radius required for traveling on the target course. Vehicle autopilot control device.