Voltage-current-based state and disturbance estimation for power-assisted control applied to an electric wheelchair

The dual-drive electric wheelchair with power assisted control is essential for improving the mobility of disabled people. In this paper, a voltage-current-based observer is proposed to realize the force/torque sensorless control of power-assisted wheelchairs. The feature of the proposed observer is that only the input voltage and armature current response of the driving motor are required for the estimation. The observer which is constructed with the motor dynamic model and two low-pass filters is employed to estimate the velocity, acceleration and external disturbance of the electric wheelchair. Then, a decoupling method is presented to retrieve the actual human input from the external disturbance estimated by the observer such that the power-assisted control can be achieved within the human's intuitive motion space. This paper presents a power-assisted control strategy which is conducted directly in both the translational and rotational motions of the dual drive wheelchair. The voltage-current-based observer designed for the force/torque sensorless power-assisted control is implemented on an electric wheelchair, and its effectiveness is verified with experimental results.