Current engine and transmission development processes typically involve extensive steady-state and simple transient testing in order to characterize the engine's fuel consumption, emissions, and performance and the transmission's efficiency and performance based on several controllable inputs such as throttle, spark advance, EGR, and shift scheduling. Steady-state and or simple transient testing these idealistic load conditions alone, however, is no longer sufficient to meet powertrain development schedule requirements. Mapping and calibration of an engine and/or transmission under transient operation has become critically important. During transient operation of the engine, the transient torque requirements on the engine are highly dependent on transmission and vehicle parameters such as torque converter, gear ratios, downstream rotational inertias, and vehicle mass. Similarly, in-vehicle transmission loading is dependent on engine and vehicle operation. As a result of this increasing dependency and the fact that utilizing actual test vehicles has become less attractive due to cost and time constraints to support powertrain development, independent engine and transmission development is becoming extremely important.
Additionally, in order to thoroughly calibrate new engines and transmissions under realistic transient conditions, more advanced testing is becoming necessary. This requires four critical elements: (1) mathematical models of the engine, transmission, and vehicle subsystems, (2) a real-time operating system and hardware, (3) a low-inertia, high-power dynamometer system, and (4) sophisticated dyno control algorithms for applied load and inertia simulation.