Continuum Robot Control Based on Virtual Discrete-Jointed Robot Models

Continuum (continuous backbone) robots are suitable for operation in unstructured environments thanks to their inherent compliance. They can adjust their shape to navigate through complex environments and grasp a wide variety of payloads with their compliant backbones. However, controller design for continuum robots is challenging due to their complex dynamics. In this paper, we introduce a new and novel strategy for trajectory control of continuum robot sections. The approach is based on a virtual discrete-jointed robot whose degrees of freedom are directly mapped to those of a continuum robot section. A conventional control strategy is developed for the virtual robot, for which inverse kinematics and dynamic equations are formulated and exploited, with appropriate transformations developed for implementation on the continuum robot. Simulations of the virtual robot computed torque control were executed and results indicate that the control method has good trajectory tracking performance. The control algorithm was implemented on a three degree of freedom section of the OctArm continuum manipulator, with decent tracking performance (steady state tracking error of merely 3mm during extension).