Ford Global Technolgoies, LLC

Ford Motor Company Limited

Michael K Liubakka

Robert Charles Baraszu

Ronald J Collins

James Raymond Winkelman

Gregory James Stout

Brian James Andonian

Alexander Timofeevich Zaremba

Thomas G Reichenbach

Lenard J Duchnowski

Paul Sisko

Timothy G Offerle

An automotive vehicle steering system has an actuator () for steering a wheel (). A shaft () passes axially through the interior of a housing () of the actuator and through a rotor tube () journaled for rotation within the housing. On the exterior of the housing one end of the shaft is coupled to the wheel. An electric motor () within the interior of the housing rotates the rotor tube when the wheel is steered by a steering wheel. An internal screw thread () on the rotor tube and an external screw thread () on the shaft are operatively coupled by a set () of transmission rollers () to provide for bi-directional transmission of motion between the rotor tube and the shaft such that rotation of the rotor tube causes the shaft to move axially of the housing to steer the vehicle wheel and axial motion of the shaft due to wheel recovery from a turn rotates the rotor tube.

Automotive vehicle steering system having an electric motor powered linear actuator shaft for turning a steered wheel

A variable assist power steering system (,) uses vehicle speed and steering wheel rate to vary the steering assist provided. A control module (,) receives vehicle speed and steering wheel rate data from sensors (,) and produces a control signal for a flow control valve actuator (,) that bypasses fluid flow from the pump (,) to a reservoir (,), rather than to the steering valve (,) thereby affecting steering valve pressure which controls the rack piston (,) which changes the angle of the front vehicle wheels used for steering. The control module (,) employs first and second calibration tables (,) to determine base and evasive desired actuator current values and then selects a final desired actuator current value using these values in combination with the steering wheel rate data.

Steering control method for providing variable assist power steering

A variable assist power steering system (10) uses vehicle speed, steering wheel rate and steering valve inlet pressure to vary the steering assist provided. A control module (30) receives vehicle speed, steering wheel rate and pressure data from sensors (24, 25, 26) and produces a control signal for a flow control valve actuator (32) that bypasses fluid flow from the pump (22) to a reservoir (36), rather than to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The control module (30) employs first and second calibration tables (38, 40) to determine the control signal that ensures adequate flow while consuming the least amount of energy.

Method and apparatus for providing variable assist power steering

An electronically assisted power steering system (10) for providing assist in response to a steering control signal includes a steering torque sensor (30) operatively connected to a vehicle hand wheel (12) for providing a torque signal indicative of applied steering torque. An electric motor control module (50) is connected to the torque sensor (30) and to an electric motor (32). The electric motor control module (50) includes an outer loop controller for generating a desired torque signal responsive to the applied steering torque. The outer loop controller includes a phase lag network in series with a second order network for compensating the desired torque signal. The electric motor control module (50) also includes an inner loop controller for generating a motor drive signal responsive to the desired torque signal output from the outer loop controller. The inner loop applies a motor drive signal to the electric motor to generate the required assistive torque.

Electrically assisted power steering apparatus

A variable assist power steering system (10) uses both vehicle speed and steering valve inlet pressure to vary the steering assist provided. A system controller (30) receives speed and pressure data from sensors (24, 26) and produces a control signal for an actuator (28) that shunts fluid flow from the pump (22) to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The controller (30) employs a calibration table (32) with entries representing actuator current, vehicle speed and inlet pressure wherein the speed and pressure fall into ranges defined by equally spaced speed points and equally or unequally spaced pressure points. Having pressure points spaced with a distance between any two sequential points a power of two in sensor counts allows manageable bilinear interpolation of current versus speed and pressure without complicated divide operators.

Variable assist power steering using vehicle speed and steering pressure

A four wheel steering strategy determines when the rear tire longitudinal slip becomes greater than the front tire longitudinal slip, either due to braking or acceleration, such that the rear tire slip angles must be increased to maintain vehicle balance with respect to the level of understeer/oversteer. The out-of-phase rear steering angle is reduced or the in-phase rear steering angle is increased to increase the rear tire slip angles and thereby correct vehicle balance. Three embodiments are disclosed which use estimated tire longitudinal slips, wheel speeds, and engine throttle information, respectively. The required inputs for the various embodiments can be obtained from independent sensors or preferably are available from other vehicle systems such as an anti-lock braking system, a traction control system or an engine management system. Advantageously, the present invention operates without requiring expensive sensors such as yaw sensors which are currently not feasible for mass market use.

Four wheel steering control utilizing front/rear tire longitudinal slip

An active suspension system uses a closed-loop feedback controller to with tunable feedback gains to produce a control signal which minimizes a cost function formed by the weighted sum of system outputs including body acceleration and wheel displacement error. The feedback gains are adaptively varied by incremental amounts which are calculated based on the 'pseudo-sensitivities' of those gains to system outputs, the pseudo-sensitivities being generated by a fixed-gain model of the suspension system and being combined using weighting factors which insure convergence in accordance with the predetermined cost function. The adaptive control provides long-term compensation for varying road conditions, variations from vehicle-to-vehicle, and changes in vehicle performance.

Active suspension system with adaptive actuator gain adjustment

An active suspension system uses a closed-loop feedback controller with tunable feedback gains to produce a control signal which minimizes a cost function formed by the weighted sum of system outputs including body acceleration and wheel displacement error. The feedback gains are adaptively varied by incremental amounts which are calculated based on the 'pseudo-sensitivities' of those gains to system outputs, the pseudo-sensitivities being generated by a fixed-gain model of the suspension system and being combined using weighting factors which insure convergence in accordance with the predetermined cost function. The weighting factors are combined with the pseudo-sensitivities in a manner in which the trade-off between body acceleration, wheel displacement error and the control signal is altered with varying magnitudes of road inputs to continually minimize the cost function for varying road inputs. The adaptive control provides long-term compensation for varying road conditions, variations from vehicle-to-vehicle, and changes in vehicle performance.

Adaptive vehicle suspension system with mechanism for varying controller

A method and system is provided for improving vehicle handling during vehicle operation in the nonlinear region of the front tires for use with a vehicle (10) having manually operable front steerable wheels (12) and electronically controlled rear steerable wheels (14). The method includes the step of calculating a desired rear steer angle based on vehicle parameters, such as vehicle speed and front wheel angle. Preferably, the method also includes the steps of determining if the vehicle is operating in the nonlinear region of the front tires, calculating a handling term if the vehicle is operating in the nonlinear region of the front tires and modifying the desired rear steer angle based on the handling term. The rear steerable wheels are then steered toward the modified desired rear steer angle.

Method and apparatus for four wheel steering control utilizing tire

A self-tuning speed control system is disclosed. The gain of the system controller is tuned to provide optimal performance based upon a sensitivity point analysis and gradient optimization of a prescribed cost index.

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Livonia, MI, United States of America

Michael K Liubakka