Form Closure for Fully Actuated and Robust Obstacle-Aided Locomotion in Snake Robots

In this letter we adapt the theory of form closure to define the form closed region: The subset of a snake robot's configuration space for which the constraints imposed by the obstacles in its environment render the system fully actuated. We show that the identification of form closed configurations is numerically feasible, and introduce the relaxed condition of form boundedness to achieve robustness in the presence of model uncertainties. We moreover show an example application where the concept of form closed region is used to produce predictable constrained motion in a cluttered environment using lateral undulation.