A combined modal-joint space control approach for continuum manipulators

Continuum manipulators continue to gain popularity due to their ability to operate within difficult to reach environments, and their inherent safety characteristics. However, their flexible nature makes them prone to both steady-state positioning errors and undesirable vibrations. We propose a combined control system incorporating both a tracking position controller to reduce steady-state error, and a modal-space controller to improve the dynamic properties of the manipulator. To this end, we develop a lumped parameter model for use as a modal-space observer. Simulation results based on a planar two-segment manipulator and experimental results from a single-segment manipulator both show marked improvement using our combined approach. The improvements observed in both simulation and experimental results include reduced settling time, higher bandwidth trajectory control capability, and an improved response to external disturbances.