| 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 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. This control topology was then tested in a single segment planar continuum manipulator testbed. Feedback in this system is based on orientation obtained from an electromagnetic localization sensor. A non-linear manipulator simulation based on a two segment planar manipulator was also used to evaluate our control system. 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. |
