Abstract: A system and method for controlling the collisions between elements of an automotive rack and pinion steering apparatus and an end-of-travel stop is presented. The system comprises a sensor for sensing a set of dynamic variables of the rack and pinion steering apparatus and operative thereby to generate as output therefrom a first set of signals indicative of the set of dynamic variables; a controller responsive to the first set of signals and operative thereby to provide as output therefrom a modified torque assist command; and a motor drive assembly drive assembly responsive to the modified torque assist command and operative thereby to provide modified torque assistance to the rack and pinion steering apparatus. In another embodiment, the dynamic data is used to calculate a torque limit to be imposed upon the torque assist command whenever the steering system is close to end-of-stop. The two embodiments may also be superimposed.

Abstract: A system and method of discriminating faults in an error signal, such as that from a control input sensor, comprises a system for and method of determining allowable limits of an error signal versus time, passing the error signal through a low-pass filter, comparing output of the low-pass filter with a threshold and outputting a fault condition when the output of the low-pass filter exceeds the threshold. The time constant or constants of the low-pass filter and the threshold are selected so that a fault condition is detected when the error signal approaches the allowable limits before exceeding them.

Abstract: An electric power steering system includes a steering wheel, a voltage-controlled electric assist motor connected to the steering wheel or column, and an electronic controller electrically connected to the assist motor that receives a first signal representing a torque command to the assist motor and a second signal representing an angular velocity of the assist motor, and produces a voltage signal according to an assist-dependent damping function of the first and second signals, and uses the voltage signal to control the voltage-controlled electric assist motor in response to the assist-dependent damping function.

Abstract: An electric motor actuator used in an environment of varying loads for varying time periods is efficiently designed to a predetermined specification in terms of both motor load and time and operated up to but not exceeding this specification over the full expected operating range. A motor load signal is low pass filtered with a plurality of time constants spanning a range of expected motor operation to generate a plurality of filtered motor load signals each associated with one of the time constants. Each of these filtered motor load signals is compared with a predetermined reference value corresponding to the associated time constant. If one or more of the filtered motor load signals exceeds the predetermined reference value with which it is compared, the one that so exceeds by the greatest margin is selected. A command current limit factor is derived from the selected filtered motor load signal and used to limit the commanded motor current.

Abstract: An electric power steering control for a motor vehicle reduces motor torque ripple and road generated disturbances communicated to the vehicle handwheel while promoting system stability. In deriving an output command torque signal to the EPS motor, the control (1) derives an electric motor speed signal, (2) differentiates the electric motor speed signal, (3) stores a schedule of gain as an increasing function of electric motor torque, (4) modifies the differentiated estimated electric motor speed signal in response to the gain to provide a damping correction value and (5) derives the output command signal responsive to the damping correction.

Abstract: A vehicle power steering system has a steering shaft with a rotational position sensor providing signal rollover so that each sensor output indicates a plurality of potential absolute steering positions separated from each other by multiples of a rollover angle. Upon each initiation of vehicle operation, the system selects, as an unadjusted steering position, one of the plurality of absolute steering positions corresponding to an initial sensor output; and the system repeatedly updates the unadjusted steering position in response to sensor output changes, including sensed rollover events. The system repeatedly tests a set of revolution offsets with the updated unadjusted steering position and excludes any which indicate an out-of-range absolute steering position. The final remaining revolution offset is latched as the correct value.

Abstract: A vehicle power steering system has a steering shaft with a rotational position sensor providing signal rollover so that each sensor output indicates a plurality of potential absolute steering positions separated from each other by multiples of a rollover angle. Upon each initiation of vehicle operation, the system selects an absolute steering positions corresponding to an initial sensor output as an unadjusted steering position and repeatedly updates the unadjusted steering position in response to sensor output changes, including sensed rollover events. The system stores data dividing a two dimensional map of possible vehicle steering operating points defined by total steering torque and steering position into a first region of likely vehicle steering system operating points, a second region of unlikely steering system operating points indicating a revolution offset in a first direction, and a third region of unlikely steering system operating points indicating a revolution offset in an opposite direction.

Abstract: A vehicle with an electric power steering system has a steering shaft with a resonant frequency of free rotational oscillation and a control which derives a driver assist torque signal, a return to center torque signal and an active damping torque signal and sums these signals to provide a motor command signal to the electric motor. The active damping torque signal is derived by filtering a generated steering shaft position signal in a filter having amplitude and phase characteristics of a differentiator from zero Hertz only through the resonant frequency of free rotational oscillation of the steering shaft and multiplying the filtered steering shaft position signal by a vehicle velocity factor derived from sensed vehicle velocity. Preferably, the electric motor is provided with one or more rotor position sensors used in the control thereof and rotor position signals from the rotor position sensors are provided as the steering shaft position signal.

Abstract: An electric power steering control apparatus comprising a vehicle steering wheel, a torque sensor for sensing torque in the vehicle steering column, a motor for providing motive force power assist to the steering system, a controller receiving the torque sensor signal and providing a motor control command to the motor responsive thereto, wherein the motor provides the motive force power assist responsive to the motor control command, and a high pass/low pass filter in the controller, wherein the high pass/low pass filter isolates low frequency components of the sensed vehicle steering system torque representing operator input torque and wherein the controller, responsive to the low frequency components determines a first, driver responsive, component of the motor control command, wherein the high pass/low pass filter isolates high frequency components of the sensed vehicle steering system torque and wherein the controller, responsive to the high frequency components, determines a second component of the motor

Abstract: In an electric power steering system in which a torque assist command is generated for controlling a motor that provides electric power assist torque at a desired torque, a method of motor control according to the steps of: determining a voltage mode motor command responsive to the torque assist command, wherein the voltage mode motor command commands a first motor torque that is (a) greater than the desired torque when the desired torque is low and (b) substantially equal to the desired torque when the desired torque is high; determining a current mode motor command responsive to the torque assist command, wherein the current mode motor command commands a second motor torque that is (a) substantially equal to the desired torque when the desired torque is low and (b) greater than the desired torque when the desired torque is high; and controlling the motor responsive to the voltage and current mode motor commands, wherein the motor assist torque is equal to a lesser of the first and second motor torques.

Abstract: An electric power steering control apparatus comprising a torque sensor coupled to a vehicle steering system for measuring steering wheel torque provided by a vehicle operator, a steering angle sensor coupled to the steering system for measuring steering wheel angle, a controller, responsive to the measured steering wheel torque and a vehicle speed, providing a sum return-to-center command, and a motor responsive to the sum return-to-center command, wherein the controller determines a low speed return-to-center command responsive to the measured steering wheel torque and a first predetermined function, determines a high speed return-to-center command responsive to the measured steering wheel torque and a second predetermined function and blends the low and high speed return-to-center commands to obtain the sum return-to-center command.