Local accessibility and stabilization of an underactuated crawling robot with changing constraints

Underactuated systems are those processing fewer actuators than degrees of freedom, but generally they are difficult to control. In this paper we realize the crawling motion by an underactuated robot. By changing the location of the fixed point of the robot to the environment, the constraint of the system is changed. Local accessibility of the system with changing the constraints as a nonholonomic system is shown. The control law based on partial feedback linearization is proposed and the stability of the closed-loop system is studied. We discuss the trajectory planning of the robot based on geometric relation. Experiments were carried out to demonstrate the effectiveness of the proposed controller.