On emulating engine and vehicle transient loads for transmission-in-the-loop experiments

This paper presents the development of real-time (RT) engine and vehicle models for emulating transient loads during transmission-in-the-loop (TIL) experiments. The models emulating these vehicle-components are required to possess sufficient fidelity to simulate engine torque pulse (ETP) and wheel-slip dynamics while being computationally efficient to run in RT. The emulation of ETP is accomplished by decomposing the waveform into inertia and combustion based components, and implemented using the high switching frequency of AC-dynamometer drive. The task of emulating wheel slip is achieved by using a RT physics based hybrid tire model developed to avoid the singularly perturbed dynamics at high velocities. Parameters of the engine model are identified using experimental data, and both models are validated in pure simulation. Finally, closed loop TIL test results are presented to demonstrate successful emulation during experimentation.