Abstract: An antilock brake control system having independently controlled left and right brakes has a control program effective at the onset of antilock operation for sensing when the vehicle is braking on a split coefficient surface and for preventing excessive yaw rate by assessing the yaw rate tendency, and when the tendency is excessive, dumping the pressure on the high coefficient side wheel and forcing that wheel into antilock modulation, thereby initializing the system to contain the yaw rate to an acceptable value.

Abstract: A wheel slip controller controls the torque input to the left and right wheels of an axle so as to strike a balance between the logitudinal forces accelerating (in a traction control system) or decelerating (in an anti-lock braking system) the vehicle and the vehicle yaw rate when the vehicle is being operated on a split-coefficient of friction surface. A vehicle yaw condition is sensed when a predetermined function of the difference in the left and right wheel speeds exceeds a threshold at low vehicle speeds and when a predetermined function of the difference in the left and right wheel slips exceeds a threshold at high vehicle speeds.

Abstract: An improved method of controlling an electro-hydraulic control system by developing a motor control command in relation to the desired force to be exerted by an electric motor on a mechanical element whose displacement determines the hydraulic pressure. The control command is comprised of two magnitude signals. The first magnitude signal must be sufficient to exert enough force to overcome a static friction characteristic of the mechanical element, and the second magnitude signal is selected to achieve a desired average current or voltage over that control period. The time constant for the control command is less than the mechanical time constant of the system, but greater than the the electrical time constant of the system. The control command may be implemented by using either current or voltage control.

Abstract: An algorithm is provided for improved lateral force during cornering while in antilock braking mode. For each wheel, the peak slip value at which maximum adhesion between tire and road occurs is determined, and the peak value is reduced by offsets (or factors) to increase lateral force according to the cornering maneuver in progress to derive a target slip value. A cornering offset and an evasive offset are functions of steering wheel angle and steering wheel rotation rate, respectively, and of vehicle deceleration. When slip is determined using average vehicle speed, a geometry correction term which is a function of steering angle, vehicle speed and deceleration is added to the target value. The offsets and the correction term have different values for inside and outside wheels.

Abstract: A control method for four wheel drive vehicles in which the front and rear wheels are not mechanically linked controls the drive torque to the vehicle wheels in proportion to vehicle loading and road surface friction coefficients in response to front and rear wheel speeds and front and rear wheel accelerations thereby reducing wheel spin.

Abstract: A strut has a cylinder body having one end closed and a piston rod which reciprocates into and out of the cylinder body through the other end thereof defining retracted and extended positions of the strut. A magnet mounted on the piston rod operates with the other end of the cylinder body in the extended position of the strut to create a magnetic force biasing the strut to the extended position. The magnet allows the strut to move from the extended position if a force sufficient to overcome the magnetic force is applied to the strut. A second embodiment has a spring mounted to the interior of the closed end of the cylinder. A first magnet is mounted on the piston rod creating a magnetic repulsive force between the two magnets urging the magnets away from each other. The spring force urging the first magnet towards the second magnet so that the strut is urged toward the extended position.

Abstract: An improved closed-loop transmission shift control in which the pressures are regulated in a manner to accelerate/decelerate the input and output shafts or the transmission in relation the progression of the shift. The control requires dynamic knowledge of the transmission input and output torques, and the preferred mechanization of the present invention employs an estimation of the input and output torque effects so that the control is carried out with only input and output shaft speed measurements. The estimations are adjusted based on the difference between the expected and actual input and output shaft speed values, so as to compensate for torque control errors as well as torque estimation errors.

Abstract: Torque proportioning between the front and rear wheels of a vehicle is achieved by controlling the speed of each rear wheel, via modulation of the hydraulic brake pressure of the rear wheel during braking, to be the same as the speed of the front wheel on the same side of the vehicle.

Abstract: A rear wheel speed reference utilized in an anti-lock brake controller as the basis for controlling the rear wheel brakes of a vehicle controlled by a common control signal is established based on the road surface condition. When the vehicle is being braked on a split coefficient of friction surface, the rear wheel speed reference is established at the wheel speed which is the lowest between the two wheels. This provides braking in accord with a select low mode of operation. However, when the two rear wheels are being braked on a uniform surface, the rear wheel speeds are processed such that an average of the two wheel speeds is provided as the rear wheel speed reference for establishing the braking control signal for the rear wheels.

Abstract: A wheel lock control system wherein the critical wheel slip producing the maximum braking force between the road surface and the tire is identified and the brake pressure is modulated continuously when an incipient wheel lockup is sensed to maintain the wheel slip value at the critical wheel slip value.