JPH10297522A - Steering assisting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a driver from having an abnormal feeling by producing an assisting steering angle on at least steered wheels and the one of wheels other than the steered wheels to make the tangential direction of a target running line along a running path parallel to the front and rear direction of a vehicle. SOLUTION: A controller 20 of a vehicle 1 calculates the steering angle δr of rear wheels 14L 14R required to make a yaw angle Δϕ zero based on a steering angle detection signal δf of the front wheels 7L, 7R supplied by a front wheel steering angle sensor 21, a steering angle detection signal δd of the rear wheels 14L, 14R supplied by a rear wheel steering angle sensor 22, a vehicle speed detection signal V supplied by a vehicle speed sensor 24, and the yaw angle Δϕ (which is formed by the tangential direction of a target running line and the longitudinal direction of the vehicle) determined based on an image transmitted by a CCD camera and supplies the steering angle control signal δc which produces the steering angle δr on the rear wheels 14L, 14R to an electric motor 10 via a drive circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering assist device that enables a more stable running by automatically generating an assist steering angle on, for example, a rear wheel of a vehicle separately from a steering operation of a driving vehicle. In particular, the driver only needs to perform a steering operation to control the lateral position of the vehicle.

[0002]

2. Description of the Related Art For the purpose of reducing the burden on the driver of a vehicle, an automatic driving device as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-81603 has been conventionally proposed.

That is, in the conventional automatic driving apparatus disclosed in the above publication, for example, a target traveling line along a lane center position is assumed, and a lateral direction of the vehicle center of gravity with respect to the target traveling line is assumed. Misalignment (horizontal position of vehicle)
Is detected on the basis of an image captured by a camera facing the front of the vehicle, and feedback control such that the lateral position becomes zero is basically executed. That is, in the conventional automatic driving device, the steering angle is automatically controlled so that the vehicle travels along a target traveling line assumed in advance, so that the vehicle can be smoothly moved along the traveling road. It was able to run.

[0004]

However, if the control is such that the lateral position of the vehicle coincides with the target value as described above, during automatic steering, the vehicle moves to a position irrelevant to the driver's intention. There is a problem that the driver feels something strange on the contrary because the driver passes through the vehicle. For example, when performing automatic steering control such that the vehicle travels along the center of the lane, the driver wants to move the vehicle to the left side of the lane when a large truck runs in the opposite lane in face-to-face traffic. However, since the vehicle travels in the center of the lane, the driver feels stress. Also,
When traveling on a curved part, in normal driving, the vehicle travels out-in-out within the range of the lane width so that the curvature of the vehicle trajectory becomes as small as possible, whereas the vehicle travels along the center position of the lane In such automatic steering control, the vehicle travels at the center of the lane, so the curvature of the vehicle trajectory becomes as large as the curvature of the traveling road, and the lateral acceleration becomes large even at the same vehicle speed as during normal driving. It gives the driver a feeling of strangeness.

[0005] The present invention has been made in view of such unresolved problems of the prior art, and gives the driver the above-mentioned discomfort without increasing the burden on the driver. It is an object of the present invention to provide a steering assist device that can prevent such a situation.

[0006]

In order to achieve the above object, according to the present invention, in order to make a tangential direction of a target traveling line along a traveling path and a longitudinal direction of the vehicle parallel to each other, a steered wheel and a steering wheel of the vehicle are provided. An auxiliary steering angle is generated on at least one of the wheels other than the steering wheel. As a result, the steering operation by the driver only affects the change in the lateral position of the vehicle, so that the driver does not need to control the yaw movement of the vehicle. The vehicle moves laterally while keeping the state parallel to the lane. Then, the driver only has to return the steering to the neutral position when the vehicle moving in the lateral direction comes to the desired position.

Specifically, in order to achieve the above object,
The invention according to claim 1 is a steering assist device applied to a vehicle including a main steering mechanism that steers a steered wheel in response to a driver's steering operation, wherein at least one of the steered wheel and other wheels is provided. And an auxiliary steering mechanism capable of giving an auxiliary steering angle to the vehicle, and controlling the auxiliary steering mechanism so that a tangential direction of a target traveling line along a traveling path and a vehicle front-rear direction are parallel to each other. It is.

In order to achieve the above object, the invention according to claim 2 is a steering assist device applied to a vehicle having a main steering mechanism that steers steered wheels in response to a driver's steering operation. An auxiliary steering mechanism capable of providing an auxiliary steering angle to at least one of the steered wheels and the other wheels, and a yaw angle which is an angle formed between a tangential direction of a target traveling line along a traveling path and a vehicle longitudinal direction. Yaw angle detection means for detecting, main steering angle detection means for detecting a steering angle of the steered wheels according to the steering operation of the driver, auxiliary steering angle detection means for detecting the auxiliary steering angle, and vehicle speed detection Vehicle speed detecting means, and auxiliary steering which calculates the yaw angle to zero based on the detection results of the yaw angle detecting means, main steering angle detecting means, auxiliary steering angle detecting means and vehicle speed detecting means. Calculation means, provided with a driving means for driving the auxiliary steering mechanism the auxiliary steering angle calculating means in response to the auxiliary steering angle calculated.

According to a third aspect of the present invention, in the steering assist device according to the second aspect, the auxiliary steering angle calculating means includes the yaw angle detecting means, the main steering angle detecting means, and the auxiliary steering angle. A state quantity estimating unit for estimating at least the state quantity of the yaw motion and the state quantity of the lateral motion based on the detection results of the detecting means and the vehicle speed detecting means; and each state quantity estimated by the state quantity estimating unit and a predetermined feedback coefficient. And an auxiliary steering angle calculation unit that calculates the auxiliary steering angle to make the yaw angle zero based on the following.

According to a fourth aspect of the present invention, in the steering assist device according to the third aspect, the state quantity estimating section estimates a yaw rate and the yaw angle as the state quantity of the yaw motion. Then, a side slip angle or a lateral displacement speed is estimated as the state quantity of the lateral motion.

According to a fifth aspect of the present invention, in the steering assist device according to the fourth aspect of the present invention, the state quantity estimating section uses the detection result of the yaw angle detecting means as the yaw angle as it is. I made it.

According to a sixth aspect of the present invention, in the steering assist device according to the third to fifth aspects, the state quantity estimating unit is a Kalman filter. Further, according to a seventh aspect of the present invention, in the steering assist device according to any one of the third to sixth aspects, the auxiliary steering angle calculation unit is configured to calculate each state amount and each state amount estimated by the state amount estimation unit. The auxiliary steering angle is calculated by summing up the values multiplied by the corresponding feedback coefficient.

[0013]

According to the present invention, the auxiliary steering mechanism is controlled so that the tangential direction of the target traveling line along the traveling path is parallel to the vehicle longitudinal direction. The driving route of the vehicle can be changed according to the driver's intention without imposing a burden on the driver, and there is an effect that a sense of discomfort given to the driver can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of an embodiment of the present invention, and is a plan view illustrating a schematic configuration of a vehicle 1.

First, the structure of the vehicle 1 will be described. In this vehicle 1, the rotational force of a steering wheel 2 operated by a driver is transmitted through a steering shaft 3, for example, in a rack-and-pinion type The information is input to the device 4. That is, the rotational force input from the steering shaft 3 to the pinion shaft 4A of the rack-and-pinion type steering device 4 is converted into a left-right advancing / retreating force of the rack shaft 4B. Side rods 5L, 5R via side rods 5L, 5R connected to
Transmitted to the knuckles 6L and 6R connected to the outer end of the
Thus, the knuckle 6L, rotates in 6R rotatably supported front wheel 7L, steering angle [delta] _f is adapted to generate the 7R.

Further, the vehicle 1 is provided with an electric motor 10 for rear wheel assist steering, and the rotational force of the electric motor 10 is applied to a pinion shaft 11A of a rack and pinion type steering device 11 for rear wheel assist steering. To be entered. Then, the rotational force input to the pinion shaft 11A is converted into the forward / backward force of the rack shaft 11B, and the forward / backward force is transmitted to the side rod 12L via the side rods 12L and 12R connected to the left and right ends of the rack shaft 11B. , 1
Knuckle 13L connected to the outer end side of the 2R, is transmitted to 13R, thereby, the knuckle 13L, wheels 14L after being rotatably supported on the 13R, 14R in the auxiliary steering angle [delta] _r is adapted to generate .

[0017] That is, the vehicle 1, a front wheel 7L according to the driver's steering operation, together with the steering angle [delta] _f as the primary steering angle occurs 7R, the rear wheels by controlling the driving of the electric motor 10 14L, 14R auxiliary steering angle δ _r is adapted to generate in.

The electric motor 10 is controlled by a controller 20 including a motor drive circuit, a microcomputer, an interface circuit such as an A / D converter and a D / A converter, and a storage device such as a RAM and a ROM. and drives in accordance with the steering angle control signal [delta] _c to be supplied.

On the other hand, in the vehicle 1, a front wheel steering angle sensor 21 composed of a rotary encoder or the like for detecting a rotation angle of the steering shaft 3, and a forward / backward movement of a rear wheel steering rack shaft 11B are detected. A steering angle sensor 22 for a rear wheel composed of a linear encoder or the like, a CCD camera 23 for photographing a running path in front of the vehicle 1, and a vehicle speed sensor for detecting a vehicle speed by detecting a rotation speed on an output side of a transmission. 24, and a detection signal δ _{f of} each sensor,
δ _d and V are supplied to the controller 20.

The CCD camera 23 is a camera for photographing a road surface several meters ahead of the vehicle 1, and the photographed image is supplied to the controller 20. Then, the controller 20 detects a target travel line along the travel path based on the image captured by the CCD camera 23, and calculates a yaw angle Δφ, which is an angle between the tangent direction of the target travel line and the front-rear direction of the vehicle. I am asking for it. Specifically, the controller 20 extracts information (for example, a center line or a side line drawn on a road surface, a guide rail, or the like) applicable as a target traveling line from an image captured by the CCD camera 23, and extracts the information. The tangential direction of the target traveling line thus determined at a position several meters ahead of the vehicle 1 is determined, and the angle between the tangential direction and a vehicle reference line assumed to extend horizontally in the vehicle longitudinal direction through the center of gravity of the vehicle 1 As the yaw angle Δφ. Note that the yaw angle Δφ is an angle between the tangential direction of the target travel line and the front-rear direction of the vehicle as described above, and “Δ” is added to distinguish it from the yaw angle obtained by simply integrating the yaw rate φ ′. .

The controller 20 controls the front wheels 7L.3 supplied from the steering angle sensor 21 for the front wheels. And the steering angle detection signal [delta] _f the 7R, and wheels 14L, steering angle detection signal 14R [delta] _d after supplied from the steering angle sensor 22 for the rear wheels, the vehicle speed sensor 2
4 and the vehicle speed detection signal V supplied from CC
Based on the yaw angle Δφ obtained based on the image sent from the D camera 23, wheels 14L, calculates the steering angle [delta] _r of 14R after necessary for the yaw angle Δφ to zero, the steering angle [delta] _r is the rear wheel 14L, and supplies to the electric motor 10 via a drive circuit (not shown) steering angle control signal [delta] _c, such as those generated 14R.

FIG. 2 is a block diagram showing the entire system including the functional configuration of the controller 20. That is,
The controller 20 functionally includes the steering angles δ _f , δ _r ,
An estimator 20A for estimating the state quantity of the vehicle 1 and the curvature of the traveling road based on the yaw angle Δφ and the vehicle speed V;
Rear wheel 14L to zero yaw angle Δφ based on the vehicle speed V supplied from the state quantity and the curvature and the vehicle speed sensor 24 A is estimated, and a regulator 20B for computing the steering angle [delta] _r required 14R, the It is comprised including.

Here, the estimator 20 in the controller 20
In order to explain the specific configurations of A and the regulator 20B, a general two-wheel model as shown in FIG. 3 is considered. The meaning of each symbol in FIG. 3 is as follows.

Φ ': yaw rate y': lateral velocity β
... Slip angle (β = y '/ V) C _f ... Cornering power of front wheel C _r ... Cornering power of rear wheel m ... Vehicle mass I ... Vehicle yaw moment of inertia δ _f
... steering angle of front wheel V ... vehicle speed a ... distance between front wheel and center of gravity b ... distance between rear wheel and center of gravity F _f ... cornering force of front wheel F _r ... corning force of rear wheel And the equation of motion of the vehicle model is state space. The expression is as follows.

[0025]

(Equation 1)

[0026] ... (1) ^{_{where, a 11 = - (a 2}} C f + b 2 C r) / IV a 13 = (bC r -aC f) / I a 31 = ((bC r -aC f) / _{^{mV 2) -1 a 33 = -}} (C f + C r) / mV b 11 = aC f / in b 12 = -bC r / I b 31 = a _{C f / mVn b 31 = C} r / mV, n Is the steering gear ratio of the front wheel steering system, and ρ is the curvature of the traveling road.

When the curvature ρ is formulated as a state variable, ρ ′ = − λρ + w (2) w is white Gaussian noise. In this equation (2), the curvature ρ changes continuously when viewed locally (focusing on a certain curved road), so that its behavior can be described by a first-order delay characteristic. Since it is determined by the conditions, it is assumed that white Gaussian noise w can be regarded as being driven. Then, when this equation (2) is substituted into the above equation (1),

[0028]

(Equation 2)

... (3) The regulator applied to such a system is called a stochastic regulator, but the actual solution is to solve the Riccati equation in the same manner as in the known deterministic regulator problem, thereby obtaining each gain of the regulator 20B.

[0030] The actual regulator 20B, to the disturbance of the steering angle δ _f by the driver, the rear wheels 14L, 14R
Since the auxiliary steering angle [delta] _r is configured to adjust the yaw angle [Delta] [phi, the equation of state when configuring the regulator 20B is as follows.

X ′ = Ax + Bu + Gw (4) where

[0032]

(Equation 3)

[0033]

(Equation 4)

Is as follows. Evaluation function when making regulator 20B ^{is, J = E [∫x T R} xx x + u T R uu udt] a ... (5). E represents an expected value, and the range of integration in [] is 0
However, as described above, the solution may be obtained assuming that there is no E [] (that is, as a deterministic regulator). Incidentally, x ^T, u ^T each matrix x, a transposed matrix of u, a ^{x T = [φ 'Δφ β} ρ] u T = [δ f δ r].

R _xx and R _uu are weighting matrices, respectively. Here, in order to suppress the occurrence of the yaw angle Δφ by increasing the weight related to the yaw angle Δφ, three rows of the matrix R _xx
It is desirable to increase the size of the elements in the third column.

The solution of this regulator (i.e., the gain of the regulator 20B), by obtaining a Riccati equation _{^{A T P + PA + R xx}} -PBR uu -1 B T P = 0 ...... satisfy (6) matrix P, K _{r = [- K r1 -K r2 -K} r3 -K r4] = obtainable by ^{_{R uu -1 B T P ...... (}} 7). That is, the matrix K _r is
A gain of B, K _r1 ~K _r4 is state feedback coefficient.

[0037] If the regulator gain K _r in this way is obtained, the rear wheel 14L in order to zero yaw angle Δφ, 1
Steering angle [delta] _r required 4R can be determined as _{δ r = K r1 φ '+} K r2 Δφ + K r3 β + K r4 ρ ...... (8).

That is, the regulator 20B in the controller 20 executes the calculation of the above equation (8) to execute the steering angle δ _r
Is calculated. Only the yaw angle Δφ is directly detected in the present embodiment among the state quantities and the curvatures required for the calculation of the above equation (8). Therefore, in the present embodiment, in the estimator 20A, the yaw angle Δφ, the front wheel 7
L, 7R steering angle δ _f , rear wheel 14L, 14R steering angle δ
_r (Here, and using the detected steering angle [delta] _d) on the basis of the yaw rate phi ', so that to estimate the sideslip angle β and the curvature ρ is another state variable. It should be noted that the detected yaw angle Δφ is not supplied to the regulator 20B as it is, but a new yaw angle Δ
φ may be estimated together with other state quantities.

As a specific configuration of the estimator 20A, a known Kalman filter can be used.
When a Kalman filter is used for the estimator 20A, for example, the vehicle speed V is required as an element of the determinant constituting the Kalman filter.
Is supplied.

Next, the operation of this embodiment will be described. FIG. 4 is a flowchart showing an outline of processing executed in the controller 20. The processing in the controller 20 is executed in synchronization with a predetermined sampling clock.

[0041] That is, the steering assist control is executed, first, the steering angle detection signal is supplied from the steering angle sensor 21 in step 101 [delta] _f, the steering angle detection signal [delta] _d supplied from the steering angle sensor 22, The vehicle speed detection signal V supplied from the vehicle speed sensor 24 and the image supplied from the CCD camera 23 are read.

Next, the routine proceeds to step 102, where the yaw angle Δφ, which is the angle between the tangential direction of the target travel line and the front-back direction of the vehicle 1, is calculated based on the image read in step 101.

Then, the process proceeds to step 103, where the yaw rate φ ′, the sideslip angle β, and the curvature ρ are estimated by performing a calculation according to the Kalman filter based on the steering angles δ _f , δ _d , the yaw angle Δφ, and the vehicle speed V. I do. This processing corresponds to the function of the estimator 20A.

Next, the routine proceeds to step 104, where the rear wheel 1 for making the yaw angle Δφ zero according to the above equation (8).
4L, calculates the steering angle [delta] _r of the 14R. This step 1
04 When Motoma' steering angle [delta] _r, the processing proceeds to step 105, and the calculated steering angle [delta] _r, the actual rear wheels 14L, 1
The difference between the steering angle [delta] _d representing the steering angle of 4R is computed steering angle control signal [delta] _c such that zero, and outputs the steering angle control signal [delta] _c to the electric motor 10. When the process of step 105 is completed, the current process ends. Thereafter, after waiting for a predetermined sampling clock to elapse, the process returns to step 101 and the above-described processing is repeatedly executed.

FIG. 5 shows a vehicle 1 according to the present embodiment,
It is a top view showing a situation when changing lanes from the left lane 30L to the right lane 30R when traveling straight on the straight road 30, and the vehicles 1A to 1E show the order of movement when the vehicles change lanes. It is shown in FIG.

That is, in the present embodiment, the yaw angle Δ
the auxiliary steering angle [delta] _f such that the φ to zero occurs, as shown in FIG. 5, even when the lane change, the vehicle front-rear direction, the tangential direction of the running path 30 (the vertical direction in FIG. 5) It always turns. That is, the steering operation by the driver affects only the lateral movement of the vehicle 1, and the yaw angle Δφ
Need not be considered at all. Specifically, in the case of a lane change as shown in FIG. 5, when the driver steers the steering to the right, the vehicle 1 moves from the left lane 30L to the right lane while maintaining a state parallel to the tangential direction of the traveling path 30. 30
Move to R. When the driver returns the steering to the neutral position when the vehicle 1 moves to a desired position in the right lane 30R, the vehicle 1 stops moving in the lateral direction,
That is, the vehicle continues to travel straight while facing the tangential direction. The change of the traveling route is performed in the left lane 30L or 3L.
Since it is possible even within 0R, for example, when a large truck runs in the opposite lane in a face-to-face traffic, the driver can intentionally move the vehicle to the left side of the lane. Also, when the vehicle 1 travels on a curved road, as in the case shown in FIG. 5, the traveling route of the vehicle 1 in the traveling road can be selected by the driver's steering operation. -It is also possible to take a traveling route such as out, the driver only has to control the lateral movement of the vehicle 1 by steering operation, and the vehicle 1 always faces the tangential direction of the curved road. I will run.

The behavior of the vehicle 1 is not limited to the yaw motion state quantity, but is also fed back by the lateral motion state quantity (in the present embodiment, the side slip angle β) of the rear wheels 14L and 14R. than is possible because controlling the steering angle [delta] _r. In other words, in order to eliminate or reduce the influence of the lateral movement on the yaw movement, the state quantity of the lateral movement may be appropriately fed back.

On the other hand, the yaw angle Δ
When the control for making φ zero is executed, the behavior of the vehicle 1 as in the present embodiment cannot be achieved. This will be briefly described based on straight running.

First, since the vehicle is traveling straight ahead, the curvature ρ = 0
And can be. Taking the lateral displacement velocity y _c ′ instead of the state variable β, y _c ′ = V (φ + β). The lateral displacement y _c is a target travel line at the center of gravity of the vehicle (for example, a line extending along the center in the width direction of the travel path).
From the horizontal direction.

At this time, the above equation (4) is as follows: x ′ = Px + Qu (9) However,

[0051]

(Equation 5)

[0052] a ^{_{and, p 11 = - (a 2}} C f + bC r) / IV p 12 = (aC f -bC r) / I p 13 = (bC r -aC f) / IV p 31 = (bC r _{-aC f) / mV p 32 =} (C f + C r) / m p 33 = - a _{(C f + C r) /} mV q 11 = -bC r / I q 31 = C r / m.

FIG. 6 is a block diagram of the vehicle when the state feedback is applied based on the above equation (9). As the state feedback coefficient, the feedback coefficient for the yaw rate φ ′ is K _{* 1} , the feedback coefficient for the yaw angle Δφ is K _{* 2} , and the feedback coefficient for the lateral displacement velocity y _c ′ is K _{* 3} .

[0054] Here, as shown in FIG. _{6, F 11 = p 11 -q} 11 K * 1 F 12 = p 12 -q 11 K * 2 F 13 = p 13 -q 11 K * 3 F 31 = p ₃₁ and _{-q 31 K * 1 F 32 =} p 32 -q 31 K * 2 F 33 = p 33 -q 31 K * 3.

Then, the driver turns the front wheel to the steering angle δ _f
Is generated, a yaw moment and a lateral force are applied to the vehicle. In the present invention, since the yaw angle Δφ is adjusted, in order to realize this by PID control, it is necessary to steer the rear wheels to cancel the yaw moment. , F ₁₁ block and F
₁₂ blocks. These blocks have a yaw rate φ '
By steering the rear wheels with respect to the yaw angle Δφ and the yaw angle Δφ, the yaw moment is canceled. Incidentally, in classical control, detecting the yaw angle Δφ and feeding back the yaw angle Δφ corresponds to proportional control (P control), and feeding back the yaw rate φ ′ corresponds to differential control (D control).

However, the yaw movement is affected not only by the above factors but also through the _F13 block. This corresponds to a yaw moment that is generated when the vehicle is displaced in the lateral direction, a slip angle is generated in the front wheels and the rear wheels, and a cornering force is generated. As long as there is this effect, F ₁₁ blocks and F
_With only ₁₃ blocks, the yaw angle Δφ cannot be made zero. That is, the transient adjustment of the yaw angle Δφ is impossible only by feeding back the yaw angle Δφ and the yaw rate φ ′, and in order to make the yaw angle Δφ zero even in the transient state, the lateral displacement velocity y _c ′ Feedback is essential. Incidentally, the optimal regulator, such as in the present embodiment, in a feedback coefficient _{K * 3 = -p 13 / q} 11, for acting the state feedback such that F ₁₃ = 0, yaw angle even in a transient state Δφ Can be made zero.

That is, when only the state quantity related to the yaw motion is fed back as in the PID control, the yaw angle Δφ is generated when the driver steers the steering, for example, rightward. It is necessary to control the vehicle to a desired position by controlling the lateral movement while setting the angle Δφ to zero, and the configuration of the present embodiment need only control the lateral movement. The operation becomes more complicated and the burden on the driver increases accordingly.

FIGS. 7A and 7B are waveform diagrams showing simulation results (solid lines) of the present embodiment. FIG. 7A shows a lateral displacement y _c , FIG. 7B shows a yaw angle Δφ, and FIG. 7
L, respectively show a steering angle [delta] _f the 7R. As a comparative example, a simulation result (dotted line) of a normal vehicle that does not control the rear wheels 14L and 14R is also shown.

In this simulation, a vehicle in a straight traveling state is slightly displaced in the lateral direction.
According to the present embodiment, even in the transient state, the yaw angle Δφ
It can be seen that the driver does not have to worry about the yaw movement and only needs to perform the steering operation while checking the lateral position of the vehicle. On the other hand, in the comparative example, since the yaw angle Δφ occurs in the transient state, the steering operation becomes more complicated than in the present embodiment.

Here, in the present embodiment, the front wheel 7
L and 7R correspond to steered wheels, rear wheels 14L and 14R correspond to wheels other than steered wheels, and the steering wheel 2, steering shaft 3, rack and pinion type steering device 4, side rods 5L and 5R and knuckle 6 are provided.
L and 6R constitute a main steering mechanism.
0, rack and pinion type steering device 11, side rods 12L, 12R and knuckles 13L, 13R
The steering angle sensor 21 corresponds to the main steering angle detecting means, and the steering angle sensor 22 corresponds to the auxiliary steering mechanism. The vehicle speed sensor 24 corresponds to the vehicle speed detecting unit, the estimator 20A and the regulator 20B of the controller 20 and the processing of steps 103 and 104 correspond to the auxiliary steering angle calculating unit. And the processing in step 105 correspond to the driving means, the processing in the estimator 20A and step 103 correspond to the state quantity estimating section, and the processing in the regulator 20B and step 104 correspond to the auxiliary steering angle calculating section.

In the above-described embodiment, the yaw angle Δφ, which is the angle between the tangential direction of the target travel line and the longitudinal direction of the vehicle, is detected based on the image captured by the CCD camera 23. However, the present invention is not limited to this. For example, AHS in which a magnetic marker is embedded in a traveling path
In the case of (highway system), magnetic sensors may be attached to the front and rear of the vehicle, and the yaw angle Δφ may be obtained from the detection signals of the magnetic sensors. Alternatively, GPS antennas may be attached to the front and rear of the vehicle. From the position of the vehicle, the yaw angle of the vehicle with respect to the absolute space, and road map information, the yaw angle Δ
φ may be obtained, or the distance between a vehicle and a guardrail installed along a traveling path as disclosed in Japanese Patent Application Laid-Open No. 3-293411 previously proposed by the present applicant may be determined. Measurement may be performed using ultrasonic waves at two positions before and after the vehicle, and the yaw angle Δφ may be calculated from the distance,
Alternatively, a plurality of methods may be combined.

In the above embodiment, the rear wheels 14L,
Although the 14R is assisted in steering, the front wheel may be assisted, or both the front wheel and the rear wheel may be assisted. If the auxiliary steering is performed, not only the yaw angle Δφ can be made zero, but also the lateral movement speed can be arbitrarily changed by control.

In the above embodiment, the controller 20 is configured based on the optimum regulator.
The control is not limited to the optimal control, but may be H infinity control or sliding mode control.

In the above embodiment, the estimator 20A
In the above, the side slip angle β is estimated as the state quantity of the lateral motion, but the configuration may be such that the estimator 20A estimates the state quantity of another lateral motion (for example, the lateral displacement speed).

Further, in the above embodiment, the conditions for executing the auxiliary steering control are not particularly described. For example, the auxiliary steering control is stopped when the vehicle speed is low (10 Km / h or less) or when the vehicle is traveling backward. You may do so. In other words, when parking in a garage, parallel parking, or avoiding obstacles at a low speed, the vehicle automatically moves in parallel with the tangent direction of the target traveling line. This is because it is more convenient for the angle Δφ to freely change.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a vehicle showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control system.

FIG. 3 is a two-wheel model diagram of a vehicle.

FIG. 4 is a flowchart showing an outline of processing executed in a controller.

FIG. 5 is a diagram illustrating the behavior of the vehicle in the embodiment.

FIG. 6 is a block diagram of a control system when PID control is performed.

FIG. 7 is a waveform chart showing a simulation result.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Steering wheel 3 Steering shaft 4 Rack and pinion type steering device 5L, 5R Side rod 6L, 6R Knuckle 7L, 7R Front wheel (steering wheel) 10 Electric motor 11 Rack and pinion type steering device 12L, 12R Side rod 13L, 13R Knuckles 14L, 14R Rear wheels (wheels other than steered wheels) 20 Controller 20A Estimator (state quantity estimating unit) 20B Regulator (auxiliary steering angle calculating unit) 21 Steering angle sensor (main steering angle detecting means) 22 Steering angle sensor (auxiliary) Steering angle detecting means) 23 CCD camera 24 vehicle speed sensor (vehicle speed detecting means)

Claims (7)

[Claims] 1. A steering assist device applied to a vehicle including a main steering mechanism that steers steered wheels in response to a steering operation of a driver, wherein at least one of the steered wheels and other wheels is assisted by steering. An auxiliary steering mechanism capable of providing an angle is provided, and the auxiliary steering mechanism is controlled such that a tangential direction of a target traveling line along a traveling path is parallel to a vehicle front-rear direction. Steering assist device. 2. A steering assist device applied to a vehicle provided with a main steering mechanism for steering a steered wheel according to a steering operation of a driver, wherein at least one of the steered wheel and other wheels is assisted by steering. An auxiliary steering mechanism capable of giving an angle, a yaw angle detecting means for detecting a yaw angle which is an angle between a tangent direction of a target traveling line along a traveling path and a vehicle front-rear direction, and Main steering angle detecting means for detecting a steering angle of the steered wheels, auxiliary steering angle detecting means for detecting the auxiliary steering angle, vehicle speed detecting means for detecting a vehicle speed, yaw angle detecting means, main steering angle detecting means. Means, an auxiliary steering angle calculating means for calculating the auxiliary steering angle to make the yaw angle zero based on the detection results of the auxiliary steering angle detecting means and the vehicle speed detecting means, and the auxiliary steering angle calculating means calculated by the auxiliary steering angle calculating means. Steering assist apparatus characterized by comprising a driving means for driving the auxiliary steering mechanism according to the steering angle. 3. The auxiliary steering angle calculating means, based on the detection results of the yaw angle detecting means, the main steering angle detecting means, the auxiliary steering angle detecting means and the vehicle speed detecting means, at least a state quantity of the yaw movement and a lateral movement. A state quantity estimating section for estimating a state quantity, and an auxiliary steering angle for calculating the auxiliary steering angle such that the yaw angle becomes zero based on each state quantity estimated by the state quantity estimating section and a predetermined feedback coefficient. The steering assist device according to claim 2, wherein the steering assist device includes a calculation unit. 4. The state quantity estimating unit estimates a yaw rate and the yaw angle as the state quantity of the yaw motion, and estimates a side slip angle or a lateral displacement speed as the state quantity of the lateral motion. The steering assist device according to claim 3. 5. The steering assist device according to claim 4, wherein the state quantity estimating unit uses the detection result of the yaw angle detection unit as the yaw angle as it is. 6. The steering assist device according to claim 3, wherein the state quantity estimating unit is a Kalman filter. 7. The auxiliary steering angle calculating section calculates the auxiliary steering angle by summing values obtained by multiplying each state quantity estimated by the state quantity estimating section and a feedback coefficient corresponding to each state quantity. The steering assist device according to any one of claims 3 to 6, wherein the steering assist device is configured as follows.