Abstract
An improved human–robot collaborative control scheme is proposed in a teleoperated minimally invasive surgery scenario, based on a hierarchical operational space formulation of a seven-degree-of-freedom redundant robot. Redundancy is exploited to guarantee a remote center of motion (RCM) constraint and to provide a compliant behavior for the medical staff. Based on the implemented hierarchical control framework, an RCM constraint and a safe constraint are applied to the null-space motion to achieve the surgical tasks with human–robot interaction. Due to the physical interactions, safety and accuracy of the surgery may be affected. The control framework integrates an adaptive compensator to enhance the accuracy of the surgical tip and to maintain the RCM constraint in a decoupled way avoiding any physical interactions. The system performance is verified on a patient phantom. Compared with the methods proposed in the literature, results show that the accuracy of both the RCM constraint and the surgical tip is improved. The compliant swivel motion of the robot arm is also constrained in a defined area, and the interaction force on the abdominal wall becomes smaller.
Highlights
I N teleoperated Minimally Invasive Surgery (MIS), the surgical tool tip must go through small abdominal incisions during the teleoperated surgery
A method of improved human-robot collaborative control is introduced for the teleoperated surgery in this paper
Compared to the method proposed by Sandoval et al [5], the surgical task accuracy is improved, the Remote Center of Motion (RCM) constraint and interaction force are constrained into a smaller area
Summary
I N teleoperated Minimally Invasive Surgery (MIS), the surgical tool tip must go through small abdominal incisions during the teleoperated surgery. The redundancy was utilized to provide flexible workspace [6][13] and an adaptive decoupling controller [14] was applied to achieve the RCM constraint. The surgical task implementation in [8] is improved with our novel strategy by achieving RCM constraint in the 1st Null-space of the Jacobian matrix of surgical tip. We introduce a decoupled fuzzy compensator to compensate the disturbance, maintaining the RCM constraint and improving the surgical accuracy, achieving human-robot collaborative control in teleoperated surgery. The force to achieve RCM can be mapped into joint torques using the controller (τN ∈ Rn), which is defined as: τN (I. where JN ∈ 3n−m is the Jacobian matrix from the robot base to the null-space kinematics, and JT(q)+M is the inertia-weighted pseudo-inverse matrix [19]: JT(q)+M = (JT(q)M(q)−1 JT(q)T)−1 JT(q)M(q)−1 (14). In our previous work [6][8], a safe swivel motion constraint [ψmin f , ψmax f ] is defined, which is assumed to depend on the actual situation, and a virtual force Fψ is defined to prevent the swivel motion from exceeding the boundary
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