[54] STEERING AND BRAKE CONTROLLING SYSTEM
[75] Inventors: Dean C. Karnopp; Yoshiyuki Yasui, both of Davis, Calif.
[73] Assignee: Aisin Seiki Kabushiki Kaisha, Kariya, Japan
[21] Appl. No.: 331,343
[22] Filed: Mar. 31, 1989
[51] Int. CI.* B62D 5/00; B62D 6/00
[52] U.S. CI 180/140; 180/141;
180/142; 180/79.1; 180/244; 280/91; 303/96;
303/700; 364/426.02
[58] Field of Search 180/141, 142, 140, 132,
180/79.1, 233, 244; 280/91; 303/96, 97, 100;
364/426.02
[56] References Cited
U.S. PATENT DOCUMENTS
3,011,579 12/1961 Milliken, Jr. et al 180/142
4,690,431 9/1987 Ito et al 180/140 X
4,706,771 11/1987 Kawabe et al 180/142
4,706,978 11/1987 Ito 180/142
4,718,685 1/1988 Kawabe et al 180/142 X
4,722,545 2/1988 Gretz et al 180/141 X
4,765,.433 8/1988 Fujii et al 180/244
4,773,012 9/1988 Ito et al 180/142 X
4,840,389 6/1989 Kawabe et al 180/140 X
FOREIGN PATENT DOCUMENTS
122078 6/1986 Japan 180/79.1
200065 9/1986 Japan 180/140
4674 1/1987 Japan 180/142
34846 2/1987 Japan 180/79.1
160960 7/1987 Japan 180/79.1
258867 11/1987 Japan 180/140
207732 8/1988 Japan 180/233
235173 9/1988 Japan 180/242
11538 4/1989 Japan 180/244
103579 4/1989 Japan 180/79.1
727169 4/1980 U.S.S.R 180/79.1
Primary Examiner—Mitchell J. Hill
Attorney, Agent, or Firm—Burns, Doane, Swecker &
Mathis
[57] ABSTRACT
Steering and braking are coordinated and controlled according to a sensed yaw rate error or lateral acceleration error to increase vehicle stability without increasing braking distance. A desired yaw rate or lateral acceleration rate is computed from the vehicle velocity and the steering wheel angle. If the yaw rate or the lateral acceleration is excessive, indicating instability, and the brakes are being operated, then both steering and braking are controlled to reduce the yaw rate or lateral acceleration rate. In all other cases, steering control alone is performed. The yaw rate or lateral acceleration rate is reduced under steering control by adjusting wheel positions in a direction opposite the direction of yaw or lateral acceleration. The control system of the present invention- is applicable to both two-wheel and four-wheel steering and braking. The yaw rate or lateral acceleration is further reduced under braking control by decreasing brake pressure on a side of the vehicle corresponding to the direction of yaw or lateral acceleration and increasing brake pressure on the opposite side of the vehicle. In the case of anti-lock brakes, pressure is not increased beyond a slip rate threshold. Rather than controlling brake pressure, the slip rate threshold itself may be controlled in like manner to reduce the yaw rate or lateral acceleration.
21 Claims, 10 Drawing Sheets
