Abstract: A preceding vehicle, an inter-vehicle distance between a self vehicle and the preceding vehicle, vehicle speeds of the self vehicle and the preceding vehicle, an operation of a cruise control, a braking operation, a brake pressure and the like are detected and inputted to a cruise control unit. Based on these input signals, the cruise control system selects a constant speed running mode when the inter-vehicle distance is larger than a specified value and selects a following-behind running mode when the inter-vehicle distance is smaller than the specified value. When the constant speed mode is selected, the vehicle travels at a constant preset vehicle speed by operating a throttle actuator and a brake actuator. Further, when the following-behind running mode is selected, the vehicle travels keeping the inter-vehicle distance at a specified distance by the operation of the throttle actuator and the brake actuator.

Abstract: In an automatic brake system provided with a pressure source including both an oil pump and an accumulator, one or more brake systems are controlled on the basis of pump pressure smoothly at low speed, but on the basis of accumulator pressure at medium or high speed. Since the pump pressure and the accumulator pressure can be used properly according to vehicle speed, the vehicle can be braked automatically and appropriately in case of the presence of a collision against another vehicle running ahead.

Abstract: Rear wheels are controlled based on rear-wheel slip angle (.beta.r). A desired rear-wheel steering angle (.delta.r) is expressed as .delta.r=-G(S)kr.beta.r, where G(S) is a derivative transfer function and kr is a steering coefficient. The desired rear-wheel steering angle is applied to a rear-wheel steering control system for controlling the rear wheels to the desired rear-wheel steering angle.