Gm Global Technolgoy Operations, Inc.

Scott S Kimbrough

Steven J Hallman

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.

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Warren, MI, United States of America

Scott S Kimbrough