A Database-Driven In-Cycle Engine Simulator for Control, Calibration and Robustness Testing

Increasingly, advanced engine management systems incorporate high speed Digital Signal Processing (DSP) units for analyzing high-bandwidth, in-cycle signals such as those obtained from cylinder pressure, or knock sensors. In order to develop, calibrate and test the robustness of these algorithms, it is helpful to work in a simulation environment capable of simulating high-speed in-cycle data and its interaction with the engine management and DSP control strategies. Typically, however, in-cycle simulation is both deterministic and highly computationally intensive so a realistic, cyclically-varying simulation of in-cycle data is hard to generate. In this paper an alternative approach is used, based on initially recording files of high-speed, in-cycle data at different engine conditions. This database is then used to simulate the engine response as the specified engine condition varies, by playing back data from the appropriate files at each time instant. The process is straightforward in concept, but memory management is a significant issue due to the large size of the database. These issues have been addressed, and the simulation runs in near real-time in the Matlab / Simulink environment. Different noise processes, gains, and biases can also be applied to the data to simulate the effect of faults for robustness testing without the need for expensive dynamometer tests.