Vehicle chassis control system

Abstract

A vehicle has a real time suspension control which requires, as inputs, a set of absolute body modal velocity signals. Accurate estimates of these signals are derived from relative position sensors at the body suspension points by converting the relative vertical position signals from these sensors to relative body modal (e.g. heave, pitch and roll) velocity signals and passing each of these signals through a second order low pass filter including an additional phase inversion for compensation of the 180 degree filter phase lag. Thus, the necessity of absolute body accelerometers is eliminated, for a significant cost reduction. In a vehicle having significant front to rear flexing or flexing within the front or rear suspension that can affect the accuracy of the estimated absolute body roll velocity, the normal roll velocity transformation equation is modified to include only the front or the rear pair of relative velocity signals.