Cancellation of Biodynamic Feedthrough in Vehicle Control Tasks

Szabolcs Sövényi and R. Brent Gillespie

Submitted July 2005, IEEE Transactions on Control Systems Technology

AbstractóBiodynamic feedthrough refers to the transmission of vehicle motion from the seat through the driverís body to the steering or speed control interface where it produces unintended vehicle control commands. This pathway through the body closes a feedback loop that degrades driving performance and can even produce sustained oscillations in the human-vehicle system. In certain instances these oscillations can jeopardize vehicle safety. In this paper we propose and test a model-based cancellation controller to mitigate the effects of biodynamic feedthrough. The biodynamic model is constructed in a preliminary system identification experiment in which vehicle acceleration and control interface interaction force are measured. The system identification experiment is carefully designed to capture the biodynamic transmittance rather than the driving point impedance at the control interface. In operation, the controller processes vehicle acceleration measurements through a transfer function model of the human biodynamics and a motor imposes the result as a torque that acts directly on the manual control interface.We investigated the efficacy of model-based cancellation by quantifying the manual performance of 12 human subjects using a joystick to control displacements of a single-axis motion platform upon which they were seated. Biodynamic models were individually fit and tested as cancellation controllers for each subject. Comparing performance with and without cancellation in place, the cancellation controller reduced oscillation spectral energy in the 1-7Hz band by 75 % and reduced the root mean square tracking error by 44 %. The cancellation controller also had a positive effect on the disturbance response of the drivervehicle system.