Notch filter and MPC for powered wheelchair operation under Parkinson´s tremor

This paper considers a model predictive control (MPC) strategy for mitigating the effects of Parkinson tremors on a movement-sensing, joystick controlled battery powered wheelchair with regenerative braking to extend its range between charges. Regenerative braking transforms the wheelchair model into a (switched) hybrid system. The wheelchair is represented as a joystick controlled wheeled mobile robot (WMR) having four modes of operation, propelling and regenerative braking for each wheel. The joystick is presumed to provide velocity, orientation, and position commands. To enhance safety, velocity and acceleration saturation limits are imposed as constraints on the control activation. The paper delineates a notch filter to remove the main Parkinson´s tremor followed by a model predictive control strategy to track velocity, orientation, and distance to a wall commands from the joystick. Results show significant feasible advantages for safe wheelchair operation by Parkinson´s patients with tremor.