Model-Based Cancellation of Biodynamic Feedthrough Using a Force-Reflecting Joystick

Abstract

Manual control performance on-board a moving vehicle is often impeded by biodynamic feedthrough—the effects of vehicle motion feeding through the operator’s body to produce unintended forces on the control interface. In this paper, we propose and experimentally test a model-based controller that acts through a motorized manual interface to cancel the effects of biodynamic feedthrough. The cancellation controller is based on characterization data collected using an accelerometer on the vehicle and a force sensor embedded in the manual interface and a protocol under which the manual interface is temporarily immobilized while in the grip of the operator. The biodynamic model fit to the data is based in turn on a carefully constructed model of the coupled vehicle-operator system. The impact of biodynamic feedthrough and the ability of the model-based controller to cancel its effects were estimated through an experiment in which 12 human subjects used a joystick to carry out a pursuit tracking task on-board a single-axis motion platform. Cancellation controllers derived from biodynamic models fit individually to each subject significantly improved pursuit tracking performance, as evidenced by a 27% reduction in root-mean-square tracking error, a 32% improvement in time-on-target, and an increase in crossover frequency from 0.11 to 0.15 Hz.