A New Laboratory Facility for Measuring Vehicle Parameters Affecting Understeer and Brake Steer

A new laboratory test facility for measuring the various understeer influences on complete vehicles is described. The machine actuates the body and suspension in the same manner as it occurs on the road while turning or braking. Changes in steer and camber angles of the wheels are measured as body roll, tire lateral forces, and tire aligning torques are applied to the vehicle separately or simultaneously. It makes a direct measurement of vehicle roll susceptibility (tendency to roll in a turn). Steer caused by braking, called brake steer, is measured by applying brake forces.

A description is given of the systems and interacting subsystems of the machine, which provide duplication of a wide range of actual over-the-road conditions while preventing application of unrealistic constraints to the vehicle. Design features that create the capability to obtain the desired accuracies while minimizing test time are also discussed.