Simulation of Vehicle-Transmission Interactions

Within the frame of dynamic simulation techniques, the paper describes a vehicle locomotion model, inclusive of the internal power train (engine and closed circuit hydrostatic transmission), the vehicle body dynamics and the soil-wheel interface (slip and traction coefficient). As a typical application area, the design and performance of a special class of automatic displacement controls is outlined, i.e. the "automotive" or "single directive" architectures, based on the engine governor input. Two transmission schemes are considered: PV-MF (variable pumps and fixed motor), and PV-MV (variable pump and variable motor). Several control laws are introduced, discussed and modified. At the end it is shown that a disjoint control of the pump and motor displacement (both pressure and speed sensitive) gives satisfactory and promising results.