Abstract: A controller (32) for a vehicular system (10) that includes a hand-wheel (16) and an electric motor (34) includes a torque-assist function (56) responsive to a signal representing the torque applied to the hand-wheel (16) for providing a torque-assist command to the motor (34), and a steering-pull compensator (52) responsive to a signal representing a valid ignition cycle for modifying the torque-assist command to the motor (34) by an offset corresponding to a detected steering-pull condition; where the method of control includes receiving the signal indicative of the torque applied to the hand-wheel (16), providing a torque-assist command to the motor (34) in response to the received torque signal, detecting an enabling signal related to the signal representing a valid ignition cycle, quantifying a steering-pull condition in response to the received and detected signals, and modifying the torque-assist command to the motor (34) by an offset corresponding to the quantified steering-pull condition.

Abstract: A control system that employs closed-loop control for providing active vehicle rear-wheel steering, where the control system receives longitudinal wheel slip inputs to improve the vehicle directional stability. The longitudinal wheel slip inputs can be from one or more of wheel speed, traction control on and automatic braking system on. The control system includes an open-loop controller for generating an open-loop steering control signal, a yaw rate feedback controller for generating a yaw rate feedback signal, and a side-slip rate controller for generating a side-slip rate feedback signal. The open-loop steering control signal, the yaw rate feedback signal and the side-slip rate feedback signal are combined to generate the steering control signal to steer the vehicle rear wheels.

Abstract: A vehicle stability enhancement system for a vehicle having at least one vehicle subsystem includes at least one sensor for sensing at least one vehicle parameter, at least one vehicle control system for adjusting the at least one vehicle subsystem wherein the at least one vehicle control system includes a rear wheel steering control system, at least one memory including at least one set of gain factors, and a controller responsive to the at least one sensor and the at least one set of gain factors for controlling the at least one vehicle control system.

Abstract: This invention provides a system to detect in real time the condition of jackknifing tendency during vehicle-trailer backing up, and to provide steering direction assistance. The system utilizes rates of change of a vehicle-trailer articulation angle to determine a critical articulation angle.

Abstract: This invention provides a system to detect in real time the condition of jackknifing tendency during vehicle-trailer backing up, and to provide steering direction assistance. The system utilizes rates of change of a vehicle-trailer articulation angle to determine a critical articulation angle.

Abstract: A vehicle stability enhancement system for a vehicle having at least one vehicle subsystem includes at least one sensor for sensing at least one vehicle parameter, at least one vehicle control system for adjusting the at least one vehicle subsystem wherein the at least one vehicle control system includes a rear wheel steering control system, at least one memory including at least one set of gain factors, and a controller responsive to the at least one sensor and the at least one set of gain factors for controlling the at least one vehicle control system.

Abstract: A method is disclosed for controlling the rear wheel angle in a four-wheel steering vehicle such as a pickup truck. The front wheels are steered using the conventional operator handwheel linked to the front wheels. The rear wheels are actuated with a reversible electric motor and the rear wheel angle controlled using a computer with inputs of vehicle velocity, operator handwheel position and correlated front wheel angle, and handwheel turning rate. Control of rear wheel angle starts with a correlation of ratios of rear wheel angle to front wheel angle, R/F, vs. vehicle velocity suitable, determined under steady state front steering angle and velocity conditions, to maximize the contribution of the rear wheels while avoiding side-slip of the vehicle.

Abstract: A method is disclosed for controlling the rear wheel angle in a four-wheel steering vehicle such as a pickup truck. The front wheels are steered using the conventional operator handwheel linked to the front wheels. The rear wheels are actuated with a reversible electric motor and the rear wheel angle controlled using a computer with inputs of vehicle velocity, operator handwheel position and correlated front wheel angle, and handwheel turning rate. Control of rear wheel angle starts with a correlation of ratios of rear wheel angle to front wheel angle, R/F, vs. vehicle velocity suitable, determined under steady state front steering angle and velocity conditions, to maximize the contribution of the rear wheels while avoiding side-slip of the vehicle.

Abstract: There is disclosed a method for integrating a vehicle stability enhancement system and rear wheel steering. The method includes inputting a vehicle speed and measured vehicle yaw rates. Determining a front and rear wheel steer angle. Calculating a desired yaw rate. Comparing the measured yaw rate with the desired yaw rate to determine a yaw error term. Applying a braking force to a wheel of a vehicle imparting a yaw moment based upon the magnitude of the error term calculated. The rear wheel steer angle is taken into account in calculating a desired yaw rate.

Abstract: There is disclosed a method for integrating a vehicle stability enhancement system and rear wheel steering. The method includes inputting a vehicle speed and measured vehicle yaw rates. Determining a front and rear wheel steer angle. Calculating a desired yaw rate. Comparing the measured yaw rate with the desired yaw rate to determine a yaw error term. Applying a braking force to a wheel of a vehicle imparting a yaw moment based upon the magnitude of the error term calculated. The rear wheel steer angle is taken into account in calculating a desired yaw rate.

Abstract: A brake system control for use in a vehicle with four wheels comprising the steps of: determining a desired yaw rate (454); determining a yaw torque command responsive to the desired yaw rate (806); if the vehicle is in an anti-lock braking mode during driver commanded braking, applying the yaw torque command to only one of the four wheels to release brake pressure in said one of the four wheels (258-266, 274, 278, 280, 410-418); if the vehicle is in a positive acceleration traction control mode during driver commanded acceleration, applying the yaw torque command to only one of the four wheels to apply brake pressure in said one of the four wheels (258-266, 288-292, 410-418); and if the vehicle is not in the anti-lock braking mode or in the positive acceleration traction control mode, then: (i) determining whether a vehicle brake pedal is depressed (370); (ii) if the vehicle brake pedal is depressed, applying brake force to the vehicle wheels responsive to the depression of the brake pedal (374, 412, 418), w

Abstract: A method is disclosed for controlling a backing maneuver of an automotive vehicle and trailer combination in which the vehicle has operator-actuated front wheel steering and microprocessor-actuated, reversible electric motor driven rear wheel steering. For a given initial alignment of vehicle and trailer, the computer-executed method first determines whether the driver needs to pull forward before commencing the backing operation. The driver is then requested to turn the front wheels in a direction suitable for backing the vehicle without a trailer in the desired direction. The process then determines whether the driver needs to perform counter front wheel steering before backing. Then the process controls the steering of the rear wheels during the backing operation.

Abstract: An improved closed-loop vehicle yaw control in which a yaw rate limit based on measured lateral acceleration is used during transient steering maneuvers to dynamically limit a desired yaw rate derived from driver steering input. A preliminary yaw rate limit is computed based on the measured lateral acceleration, and a dynamic yaw rate limit having a proper phase relationship with the desired yaw rate is developed based on the relative magnitudes of the desired yaw rate and the preliminary yaw rate limit. A two-stage process is used to develop the dynamic yaw rate limit. A first stage yaw rate limit is determined according the lower in magnitude of the desired yaw rate and the preliminary yaw rate limit, and a second stage yaw rate limit (i.e., the dynamic yaw rate limit) is determined according to the relative magnitudes of (1) the desired yaw rate and the second stage yaw rate limit, and (2) the first stage yaw rate limit and the second stage yaw rate limit.

Abstract: An improved vehicle active brake control based on an estimate of vehicle yaw rate, wherein the estimate is based on the speeds of the un-driven wheels, but compensated to reflect slipping of the un-driven wheels during braking. Prior to braking, the yaw rate is estimated solely on the basis of the measured speeds of the un-driven wheels. During braking, the slip speeds of the un-driven wheels are estimated based on the measured speeds, the reference speed of the vehicle and the previous estimate of yaw rate, and used to compute a new yaw rate that is compensated for the estimated slip speeds.

Abstract: A brake system control method, comprising the steps of: measuring a longitudinal speed and steering angle of the vehicle; specifying an un-damped natural frequency and a damping ratio for a linear reference model of said vehicle; determining a first gain parameter relating a desired value of steady state lateral velocity to the vehicle steering angle; computing a desired lateral velocity as a function of said first gain parameter, the measured longitudinal speed, the measured steering angle, and the specified un-damped natural frequency and damping ratio; determining a second gain parameter relating a desired value of steady state yaw rate to the vehicle steering angle; computing a desired yaw rate as a function of said second gain parameter, the measured longitudinal speed and steering angle, and the specified un-damped natural frequency and damping ratio; measuring a lateral acceleration and yaw rate of said vehicle, and forming a yaw rate command for said vehicle based at least part in a first deviation be

Abstract: An improved active brake control for carrying out a desired wheel speed differential for enhanced vehicle lateral stability while maintaining suitable front-to-rear brake pressure proportioning. During driver braking, the target speeds for the wheels of the driven axle during active brake control are determined as a combined function of the wheel speeds of the un-driven axle and the desired wheel speed differential. Specifically, the target speeds for the driven wheels are determined according to the measured speeds of the corresponding un-driven wheels, and one of the target speeds is reduced to reflect the desired wheel speed differential. If the desired wheel speed differential is designed to produce a clockwise yaw moment, the target speed for the driven wheel on the right-hand side of the vehicle is reduced; if the differential is designed to produce a counter-clockwise yaw moment, the target speed for the driven wheel on the left-hand side of the vehicle is reduced.

Abstract: An adaptive, variable effort power steering system is responsive signals from one or more low friction road surface vehicle handling controls which indicate when the system has become active in modifying handling, and thus indicates the existence of a near limit or at limit vehicle handling situation. Such controls include anti-lock braking systems (ABS), traction control systems (TCS) and integrated chassis control systems (ICCS). When such a handling limit signal is received, the power steering system responds by decreasing steering assist to provide a more "manual" steering feel as long as the handling limit situation is indicated. The handling limit signal may be a binary signal, indicating activity or no activity of an anti-lock brake system, traction control system or a chassis control system such a yaw rate control.

Abstract: An improved active brake control in which differential braking is used in a feed-forward control to develop vehicle yaw in response to a desired yaw value determined as a function of steering wheel position and vehicle speed. The desired yaw rate value is used to develop a derivative yaw component and a proportional yaw component, which are summed to form a feed-forward yaw command for differential braking. Both proportional and derivative components have limited control authority determined by dead-band and saturation thresholds, and the proportional term is subjected to a diminishing integrator which reduces the yaw command as the desired yaw rate value approaches steady-state.

Abstract: A brake system control for use in a vehicle with wheels, wheel brakes and a body, comprising the steps of: measuring a plurality of vehicle parameters; responsive to the measured parameters, determining at least a vehicle yaw rate, a vehicle slip angle, a desired yaw rate and a desired slip angle; responsive to the measured parameters, estimating a coefficient of adhesion between the vehicle wheels and a road surface; implementing a control responsive to the vehicle yaw rate and the desired yaw rate with a first authority and responsive to the vehicle slip angle and the desired slip angle with a second authority, wherein the first authority increases as the estimated coefficient of adhesion increases and decreases as the estimated coefficient of adhesion decreases; and controlling the wheel brakes responsive to the control to reduce a first difference between the vehicle yaw rate and the desired yaw rate and to reduce a second difference between the vehicle slip angle and the desired slip angle.

Abstract: In a vehicle with a first operating mode in which all vehicle wheels have substantially no lateral movement on a road surface and a second operating mode in which at least some of the vehicle wheels have lateral movement on the road surface, and with an actuator capable of affecting vehicle yaw rate, a vehicle yaw rate control method comprising the steps of: measuring an actual vehicle yaw rate; measuring vehicle steering wheel position; in the second mode of operation, determining a desired yaw rate command linearly responsive to the measured steering wheel position; wherein the actuator is controlled to minimize a difference between the measured vehicle yaw rate and the desired vehicle yaw rate.