A nonlinear elastic path controller for a robotic wheelchair

This paper proposes a nonlinear form of elastic path controller (EPC) based on the previous development of EPC with linearization feedback technique. The new EPC can deviate from the pre-designed guide path, or guideway, as far as we want and fulfill all the general designing criteria of an EPC. The problem is it can not always assure the perpendicular relationship between the position error and desired tangent when the curvature of guide path varies abruptly. The control algorithm is improved so as to reset the desired position when the position error is notably not perpendicular to the desired tangent. The new nonlinear EPC is expected to fulfill all the mobility tasks by previous linear EPC and at the same time it is able to drive the wheelchair to avoid obstacles of arbitrarily large sizes found in the guide path.