Inertia and road load simulation for vehicle testing

Abstract

Prior art electromechanical inertia and road load simulators as applied in dynamometers measure speed and acceleration, then compute and control torque--a relatively slow and inaccurate operation. This invention measures torque, then computes and controls acceleration and speed--a fundamentally different approach which provides faster action, more accurate simulation and closer repeatability. The simulator described herein includes and is controlled by a computer which is provided with inputs from a torque transducer, a speed encoder and operator entered digital signals. The computer then makes accurate and rapid computations of vehicle inertia, road load forces and generates an electrical speed control signal. This signal is provided to a controller for a power absorber, e.g., a direct current power controller which drives a direct current motor. The power absorber such as the motor is mechanically coupled to the vehicle engine or a rotating roll upon which a test vehicle drive wheel rests. Effects of cooling due to vehicle velocity may be provided by a cooling fan which is mounted in front of the test vehicle and which is hydraulically coupled to the rotating roll.