Haptic simulation of an automotive automatic gearshift: Stability analysis and design of force profiles with hysteresis

This paper presents the development and the experimental validation of a controller for the simulation of the behavior of automotive automatic gearshifts. For this purpose a gearshift simulator was developed based on 2 DOF haptic interface to evaluate users qualitative judgment of automatic gearshifts response. In fact, many car manufacturers use vehicle and primary controls simulators to evaluate the characteristics of a new model before building physical mock-ups or even prototypes. A dedicated control law was designed in order to reproduce different experimentally measured force profiles during forward and backward run of the gearshift handle. The force feedback control law was based on an impedance model with different stiffness values along the path of the gearshift. A state machine selects the characteristics of the force feedback profile according to lever position and velocity. An additional state machine implements the hysteresis behavior of the force profiles by a transition function. The transition algorithm and constraints related to stability are discussed in this paper. The rendered force/position profiles were obtained from experimental data using a real gearshift. Several gearshift response profiles were tested and simulated and experimental results were compared and highlighted good fidelity in force reproduction.