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Electrically Powered Hydraulic Steering (EPHS) has provided value in passenger car applications by reducing power consumption at engine idle, providing only the required power during high speed lane-keeping, and allowing engine-off operation of vehicles with alternative power sources. This work discusses the design modifications made to use EPHS for medium duty commercial vehicle applications. Configuration options along with communication and diagnostic interface are discussed. Bench tests show the steady-state performance of the system. Experiments are done on a medium duty truck with the EPHS as the sole source of steering power to determine the speed of steer at various vehicle speeds. Finally, the power consumption for the EPHS system is compared to a conventional engine driven pump.

This paper is concerned with power consumption analysis for conventional steering system, the importance of duty cycle before choose appropriate pump drive system, and the energy saving potential of the proposed systems. After reviewing the recent efforts in developing energy-efficient steering system, two new on-demand pump drive systems are proposed to provide varying flow according to vehicle/engine speed: one is the combination of a sized pump without flow control valve and an Electrical Power Hydraulic Steering (EPHS) unit; the other is the combination of multiple EPHS units. The energy saving advantage of the combinations will be emphasized for different duty cycles.

A computer controlled steering system providing an artificial feel or synthetic torque feedback to the driver has recently been launched into production in the commercial vehicle market. This work compares the artificial feel control strategy with prior electric power steering control strategies and hydraulic power steering. Suitability for integration with other vehicle control systems such as lane sensing and electronic stability enhancement is explored.