Abstract: A low force actuator that is used in conjunction with semi-active and passive suspension systems to provide for improved suspension and ride control for vehicles, and which overcomes stiction and provides limited active capability. The low force actuator is sized to counter the small, high frequency forces (caused by road input disturbances and stiction effects) that act on, or are transmitted between sprung and unsprung masses of the vehicle. The present invention provides for two low force actuators. The first comprises a proof mass low force electromagnetic actuator that may be connected to either the sprung or unsprung mass. In either configuration the proof mass provides an extra degree of freedom for the suspension system that decouples ride and holding control actions of the vehicle. The second comprises a differential force actuator that uses an electromagnetic actuator to provide a force between the sprung and unsprung masses of the vehicle.

Abstract: A system and method for determining the speed of a vehicle independent of angular wheel rotation rates is provided. The system generates time-varying signals corresponding to the vertical acceleration of the front and rear wheels. The front and rear wheel signals include corresponding perturbations caused by the wheels crossing road disturbances such as bumps. A time lag occurs between perturbations in the rear wheel signal and corresponding perturbations in the front wheel signal. An adaptive algorithm correlates the signals for various time delay values until a time delay value is determined which maximizes the correlation between the two signals. The calculated time delay value corresponds to the actual time lag between the front and rear wheels occurring before the rear wheels encounter a road disturbance previously encountered by the front wheels. Thus, the invention provides a determination of the actual speed of the vehicle determined independently from the angular rotation rates of the wheels.