PROJECT TITLE :
A Pneumatically Driven Surgical Manipulator With a Flexible Distal Joint Capable of Force Sensing
This paper presents a unique forceps manipulator for surgical robot systems. The forceps manipulator encompasses a highly simplified flexible distal joint, which is actuated by push-pull motions of superelastic wires. Pneumatic cylinders are employed for its driving system to comprehend high backdrivability of the versatile mechanism, enabling external force estimation without employing a force sensor. For the kinematic description, we tend to newly introduce a three-degree-of-freedom (DOF) continuum model considering expansion and contraction of the versatile joint, which permits three-axis force sensing on the forceps tip. We also developed a practical dynamic model, as well as linear-approximated elastic forces and nonlinear friction forces passionate about the joint bending angle. Effectiveness of the dynamic model is validated by open-loop management performance of the joint angles. The position control system is designed employing a PID-primarily based cascade controller with a feedforward compensator primarily based on the dynamic model. Resolution of the joint angle management is 1°, satisfying the requirement for laparoscopic surgery. An external force estimation algorithm is developed, which realizes the 3-axis sensing of translational forces working on the forceps tip. The rigid-link approximation model is additionally used to treat the calculation in singular angle, the straight position of the flexible joint. Effectiveness of the force estimator is experimentally validated employing a force sensor in 2 cases. Estimation error is 0.thirty seven N at most with a force in an exceedingly radial direction, and the estimation performance using the 3-DOF force estimator is abundant higher than the one using a conventional 2-DOF force estimator.
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