A Combined Modal-Joint Space Control Approach for Minimally Invasive Surgical Continuum Manipulators

Continuum manipulators such as robotic tele-operated cardiac catheters continue to gain popularity for use in minimally invasive surgical procedures due to 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 modalspace 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. In a clinical setting, it is our hope that these improvements will translate to reduced procedure times and improved results. Introduction & Background