The da Vinci Surgical System is one of the most established robot-assisted surgery device commended for its dexterity and ergonomics in minimally invasive surgery. Conversely, it inherits disadvantages which are lack of autonomy and haptic feedback. In order to address these issues, this work proposes an industry-inspired solution to the field of force control in medical robotics. This approach contributes to shared autonomy by developing a controller for cooperative object manipulation with force tracking utilizing available manipulators and force feedback. To achieve simultaneous position and force tracking of the object, master and slave manipulators were assigned then controlled with Cartesian position control and impedance control respectively. Because impedance control requires a model-based feedforward compensation, we identified the lumped base parameters of mass, inertias, and frictions of a three degree-of-freedom double four-bar linkage mechanism with least squares and weighted least squares regression methods. Additionally, semidefinite programming was used to constrain the parameters to a feasible physical solution in standard parameter space. Robust stick-slip static friction compensation was applied where linear Viscous and Coulomb friction was inadequate in modeling the prismatic third joint. The Robot Operating System based controller was tested in RViz to check the cooperative kinematics of up to three manipulators. Additionally, simulation with the dynamic engine Gazebo verified the cooperative controller applying a constant tension force on a massless spring-damper virtual object. With adequate model feedback linearization, the cooperative impedance controller tested on the da Vinci Research Kit yielded stable tension force tracking while simultaneously moving in Cartesian space. The maximum force tracking error was +/- 0.5 N for both a compliant and stiff manipulated object.

<p>Minimally Invasive Robotic Surgery (MIRS) has revolutionized the way modern surgery is conducted by allowing for smaller incisions, finer control, reduced pain, and faster recovery. The state-of-the-art end-effector technology used for MIRS are tools based off of the rigid-body instruments used in traditional ‘open’ surgery. The rigid nature of the end-effectors, specifically the grasping jaws, leads to a lack of force feedback when implemented in a robotic system. </p> <p>Without additional feedback from active sensing, the blanching that occurs from restricted blood flow around a grasping site is the only indication a surgeon can use to assess the force applied to a tissue. Ongoing efforts to develop active force sensing solutions are currently faced with two major obstacles: miniaturization and sterilization. The lack of force feedback causes a gap between intention and result during robotic surgery. </p> <p>This work proposes the introduction of Visual Force Feedback (VFF) through the integration of a compliant end-effector design. Visual Force Feedback is an intuition, developed through practice, that allows a surgeon to estimate the reaction force of a compliant mechanism by the deflection of the outer flexures. An understanding of the relationship between opening size, flexure deformation, and pinch force allows for rapid estimation of the force applied to a manipulated object. </p> <p>Force and dimensional data were gathered through finite element simulation and the finite element model was validated with physical experimentation on a custom test bench. Multiple functions relating the flexure deformation to the reactionary force, referred to as pinch force, for specific opening sizes were resolved. Notable observations made through the analysis of these results were: (1) a closely linear relationship between outer flexure deformation and pinch force in both experimental and computational results and (2) a higher rate of pinch force increase due to draw displacement as an effect of wider jaw opening. These findings are intended to help shrink the gap between intention and result in the field of MIRS.</p>