Flexible Automotive Strategy (FAST) for Hydrostatic Transmissions

Abstract

Starting from previous papers [1], where hydrostatic transmissions automotive controls functionalities were investigated, an embedded electronic control system was designed. It is based on a low cost electronic control unit, controlling a hydrostatic transmission with a variable displacement axial piston pump and an axial piston dual displacement motor. The pump displacement control strategy, which depends on diesel engine working point and delivery pressure, is based on a fully customisable engine performance map. Special control strategies superimposed on this strategy and depending on autorecognized working mode, that allowed excellent performance in the vehicle field test phase to be reached. Special diagnostic strategies were introduced, based on functional and congruence controls, relying on fault recovery systems, to maintain the system in a high safety condition and to modify automatically the system working mode in case of fault occurrence. This approach allows reductionof overall risks for the operator and the environment.