Suspension and Mass Parameter Measurements of Wheeled Vehicles 2015-01-2751

The United States Army Tank Automotive Research, Development and Engineering Center (TARDEC) built systems to measure the suspension parameters, center of gravity, and moments of inertia of wheeled vehicles. This is part of an ongoing effort to model and predict vehicle dynamic behavior. The new machines, the Suspension Parameter Identification and Evaluation Rig (SPIdER) and the Vehicle Inertia Parameter Evaluation Rig (VIPER), have sufficient capacity to cover most heavy, wheeled vehicles. The SPIdER operates by holding the vehicle sprung mass nominally fixed while hydraulic cylinders move an “axle frame” in bounce or roll under each axle being tested. Up to two axles may be tested at once. Vertical forces at the tires, displacements of the wheel centers in three dimensions, and steer and camber angles are measured. Contact patch can move in lateral, longitudinal and steer motions of the suspension and the small deflections of the vehicle sprung mass resulting from the contact patch forces are measured. For steer axles the steering ratio, Ackerman steer characteristics, and kingpin orientation are measured. The VIPER measures center of gravity and vehicle principle moments of inertia. The roll-yaw cross product and the center of gravity height is measured by holding the vehicle body nominally fixed to a large platform while rotating the platform about the pitch, roll, and yaw axes.