Development of a new elastic path controller for the collaborative wheelchair assistant

Abstract

This thesis proposes a new Elastic Path Controller (EPC) for the Collaborative Wheelchair Assistant (CWA) developed at the National University of Singapore. The new EPC chooses the tangent on the guide path as its reference and solves the singularity issue, thus enabling the CWA to work stably. The parameters were optimized to minimize the influence of external perturbations and parameter uncertainties. Real-time experiments showed that the driving performance of the CWA is significantly improved using the proposed EPC. To enable the CWA to overcome very large obstacles, a nonlinear EPC was also developed and its performance verified by simulation experiments. Finally, a force feedback joystick was added for users with severe vision impairment to enable them to feel the feedback force generated by environmental obstacles or deviations of the wheelchair from the guide path. Experimental results indicated that the force feedback joystick greatly improves the approaching and obstacle avoidance performance of the CWA.