Method for controlling the front wheel steer angle
First Claim
1. A method for controlling a front wheel steer angle δ
-
f of a vehicle having a front wheel steering system, comprising the steps of;
detecting the speed of the vehicle;
detecting a value of a yaw rate r of the vehicle;
computing parameters T1 and Td for respectively time delay and damping properties of the yaw response of the system as a function of the detected speed; and
steering the front wheels of the vehicle at the front wheel steer angle δ
f which is computed as a sum of a steering wheel input angle feed-forward term f1 (δ
sw) which is a function of the steering wheel input angle δ
sw, and a yaw rate feed-back term f2 (r) which is a function of the detected value of the yaw rate r, according to the formula
space="preserve" listing-type="equation">δ
.sub.f =f.sub.1 (δ
.sub.sw)+f.sub.2 (r);
(7) and based on a transfer function of the yaw rate feed-back term f2 (r) with respect to the yaw rate r given by ##EQU10## where s is the Laplace variable and { } denotes the Laplace transformation.
1 Assignment
0 Petitions
Accused Products
Abstract
The method of the present invention improves the damping property of the yaw motion of the vehicle by feeding back a detected yaw rate value in a dynamic sense for compensating the front wheel steer angle so as to increase the damping coefficient of the yaw motion of the vehicle. By controlling the front wheel steer angle by accounting for not only the proportional term of the steering wheel input angle but also the derivative term which is proportional to the steering wheel input angular speed, in the feed-forward control of the front wheel steer angle in relation with the steering operation by the driver, and by appropriately varying the control parameters of the yaw rate feed-back and the steering wheel input feed-forward, the yaw response of the vehicle can be made proportional to the steering wheel input, and the response delay in the yaw rate against the steering wheel input can be reduced to substantially zero.
24 Citations
12 Claims
-
1. A method for controlling a front wheel steer angle δ
-
f of a vehicle having a front wheel steering system, comprising the steps of;
detecting the speed of the vehicle; detecting a value of a yaw rate r of the vehicle; computing parameters T1 and Td for respectively time delay and damping properties of the yaw response of the system as a function of the detected speed; and steering the front wheels of the vehicle at the front wheel steer angle δ
f which is computed as a sum of a steering wheel input angle feed-forward term f1 (δ
sw) which is a function of the steering wheel input angle δ
sw, and a yaw rate feed-back term f2 (r) which is a function of the detected value of the yaw rate r, according to the formula
space="preserve" listing-type="equation">δ
.sub.f =f.sub.1 (δ
.sub.sw)+f.sub.2 (r);
(7)and based on a transfer function of the yaw rate feed-back term f2 (r) with respect to the yaw rate r given by ##EQU10## where s is the Laplace variable and { } denotes the Laplace transformation. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
6. The method of claim 1, further comprising the steps of:
-
performing the step of computing in a computer; providing a resulting drive signal representing a correction to the steering wheel angle based on the step of computing to a motor; and driving a steering gear box of the vehicle by the motor so as to control the front wheel steer angle.
-
-
7. The method of claim 6, wherein the step of driving the steering gear box is performed by a geared addition mechanism.
-
f of a vehicle having a front wheel steering system, comprising the steps of;
-
8. A method for controlling front wheel steer angle in a vehicle having a front wheel steering system, comprising the steps of:
-
detecting the speed of the vehicle; detecting a yaw rate of the vehicle; computing parameters for damping and time delay of a yaw response of the system as a function of the detected speed; and steering the front wheels of the vehicle at the front wheel steer angle which is computed as the sum of a steering wheel input angle feed-forward term which is a function of a steering wheel input angle, and a yaw rate feed-back term which is a function of the detected yaw rate; and based on a transfer function of the yaw rate feed-back term which is a function of the computed damping and time delay parameters. - View Dependent Claims (9, 10, 11, 12)
-
Specification