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Smith, Jarett M.
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Efficiency Considerations in the GM Impact Electric Vehicle: Ride. Handling, and Steering Function

Delphi Chassis Systems-Richard J. Kowalczyk
Delphi Saginaw Steering Systems-Jarett M. Smith
Published 1996-02-01 by SAE International in United States
The design of a practical battery powered vehicle must feature efficiency in every system, in order to provide maximum range given limited on-board energy storage. As GM's impact electric vehicle was designed exclusively for battery power, priority consideration of efficiency was given to the design of every function in the vehicle. This paper addresses such considerations in one of the major functions of the chassis system: ride, handling, and steering.The ride, handling, and steering function is a major player in the efficiency of Impact. It includes such energy dissipaters as tire rolling resistance, component deformations or accelerations due to road surface irregularities, suspension viscous damping, and energy requirements of power assisted controls.Also factors in design efficiency are limited packaging envelopes associated with a highly aerodynamic body, and last but not least, mass efficiency of the chassis components. These factors were all considered in an effort to develop innovative chassis systems contributing to vehicle efficiency while providing pleasible ride, handling, and steering to the customer.The results of this effort are chassis systems which contribute significantly to…
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An Analytical Control Systems Approach to Steering Shudder

Delphi Saginaw Steering Systems-Jarett M. Smith
General Motors-Gary R. Ferries, R. Larry Arbanas
Published 1995-05-01 by SAE International in United States
Historically, power steering shudder, a vibration which occurs while steering a vehicle at low speeds, has been approached with systematic component-swapping experiments. This approach was time consuming and did not necessarily yield satisfactory results. In this paper it is shown that steering shudder can be analytically approached as a control system with a closed-loop limit cycle caused by the interaction of the chassis and the steering system. This approach provides a metric for determining a vehicle's propensity to shudder and allows quick predictions of the results of changing components.The approach is model-based, and incorporates chassis and hydraulic system components. Results obtained from the control systems analysis have been validated by a vehicle study, which showed a strong correlation between subjective evaluations and the stability metric provided by the analysis. The control systems approach has been used to develop robust shudder solutions for a number of vehicle platforms.
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