Gm Global Technolgoy Operations, Inc.

Steven J Hallman

Scott S Kimbrough

Kenneth Lee Westercamp

Rao M Chalasani

An improved rear steering control system employing separate closed-loop feedback controller and open-loop feedforward control paths. The response characteristics of the open-loop and closed-loop control paths are separately scheduled to optimize the overall system performance. In particular, the authority and delay properties of the two paths are independently varied to achieve desired control objectives. As a result, the advantages of both open-loop and closed-loop control are achieved with a single control system.

Four wheel steering system with closed-loop feedback and open-loop

The driver steering inputs of a closed-loop reference model rear vehicle steering system are measured and subjected to a filter function that delays application of the measured input to the reference model. Externally generated steering inputs appearing in the parameters measured for closed-loop control are subjected to a different filter function which imparts only minimal delay of the signal transmission. As a result, the rear steer control responds at a first, relatively slow rate to driver steering inputs, and a second, relatively fast rate to externally generated disturbances.

Closed-loop four wheel steering system having dual response rate rear

An electric steering system for automobiles includes a tubular main housing disposed on a transverse axis of the vehicle between two steerable road wheels. A left steering rack is slidably disposed in the main housing and connected to the left road wheel. A right steering rack is slidably disposed in the main housing and connected to the right road wheel. A pair of reversible electric motors at opposite ends of the main housing drive the steering racks independently of each other through corresponding pinion drive assemblies. The inboard end of the left steering rack telescopes into a bore in the inboard end of the right steering rack. The inboard end of the left steering rack has an annular shoulder which is captured in the bore by a rack rack nut on the inboard end of the right steering rack so that withdrawal of the left steering rack from the bore is prevented. The telescopic connection permits enough relative movement between the steering racks to allow an electronic control to optimally position each road wheel during steering maneuvers but is sufficiently small that the wheels can be acceptably steered together by one motor if the other becomes inoperative.

Electric steering system for automobiles

An electric power assisted rack and pinion steering gear for steering the dirigible wheels of a vehicle comprising a rack housing with an end mounted electric motor which rotatably drives a ball nut screw on which a ball nut is mounted for linear movement; the ball nut is mounted in the gear housing and is attached to manually driven rack and provides a carrier forming steering gear output to the tie rods connected to the dirigible wheels of the vehicle.

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Saginaw, MI, United States of America

Steven J Hallman