Vibration control based on dynamic compensation in an electric power steering system

The market for power assist steering in small cars is expanding. Most common among the products rapidly coming to the market are electrically powered hydraulic units and electrically powered systems that act directly on the steering column or on the steering gear. Control system stability and system vibrations are always a concern. While the system synthesized in this paper is a straight-forward torque amplifier, the compensation necessary to assure control system stability, attenuate vibrations and preserve bandwidth can be a challenging control design problem. Although the system is inherently nonlinear, it has been demonstrated that the linear approximation is sufficiently accurate to provide valid results over a useful range of operation. We discuss the dynamic model of a power steering system. Dynamic compensator design and comparison analysis are given. Earlier results obtained by authors on dynamic and stability analysis of a power steering system with an ideal actuator and development of quantitative measures of a steering system performance are presented