A Method to Improve Stability and Transparency for Mechanical Hardware-in-the-Loop Simulation

Preprint, 2021

In mechanical hardware-in-the-loop (MHIL) simulation the test hardware and the simulated environment are coupled by an interface, which typically is a dynamometer rig. This interface determines the simulation accuracy and robustness. In this work, MHIL simulation is analysed in a linear robust control framework. The system consists of an inner loop formed by the load motor controller and the rig, and an outer loop formed by the test hardware and the simulated environment. While the inner loop tracking set the overall performance, instability and poor performance may be introduced by the outer loop. We demonstrate how delay tolerance of MHIL simulation varies with the outer loop dynamics. A new method is introduced to improve the robustness and accuracy. The method utilizes flexibility of the simulation model, and only software changes are needed. The proposed method is applied to an MHIL simulation for vehicle and electric power assisted steering (EPAS) system test. The effectiveness of the method is shown analytically and experimentally.