Stiffness Control of Surgical Continuum Manipulators.

Med. Sch., Cardiac Surg. Dept., Harvard Univ., West Roxbury, MA, USA
IEEE Transactions on Robotics (Impact Factor: 2.57). 01/2011; 27:334-345. DOI:10.1109/TRO.2011.2105410
Source: IEEE Xplore

ABSTRACT This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approx- imation of a continuum robot's coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot con- figuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness con- trol to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated ex- perimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions.

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