Robot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional techniques. To improve dexterity and back-drivability of the existing planar remote center-of-motion (RCM) mechanism, on which an active prismatic joint is required to drive the surgical tool move in–out of the patient's body, a two degrees-of-freedom (DOFs) planar RCM mechanism is proposed by constructing virtual parallelograms in this paper. The mechanism can be considered as a generalized double parallelogram; both of the actuated joints are revolute joints. This feature enhances the intrinsic back-drivability of the mechanism. The mathematical framework is introduced first to prove that the mechanism could execute RCM. Then, the inverse kinematics of the planar mechanism is solved, and the Jacobian matrix is derived in this paper. Further, the singularity and the kinematic performance based on the kinematic equations are investigated, and the workspace of the mechanism is verified. Finally, a prototype was built to test the function of the proposed RCM mechanism. The results show that the mechanism can fulfill the constraint of MIS, and it can be used as the basic element of the active manipulator in an MIS robot.

Stochastic Coordinate Descent (SCD) methods are among the first optimization schemes suggested for efficiently solving large scale problems. However, until now, there exists a gap between the convergence rate analysis and practical SCD algorithms for general smooth losses and there is no primal SCD algorithm for nonsmooth losses. In this paper, we discuss these issues using the recently developed structural optimization techniques. In particular, we first present a principled and practical SCD algorithm for regularized smooth losses, in which the one-variable subproblem is solved using the proximal gradient method and the adaptive componentwise Lipschitz constant is obtained employing the line search strategy. When the loss is nonsmooth, we present a novel SCD algorithm, in which the one-variable subproblem is solved using the dual averaging method. We show that our algorithms exploit the regularization structure and achieve several optimal convergence rates that are standard in the literature. The experiments demonstrate the expected efficiency of our SCD algorithms in both smooth and nonsmooth cases.

Background A new device has been added to the Chinese MicroHand surgical robot family, developed based on the successful application of control algorithms. As a benefit of using these specialized control algorithms, the motion mapping relation can be accommodated into the system without the help of a built-in image system, resulting in a novel Chinese domestic surgical robot with two arms called MicroHand SII, which is different from the former MicroHand S and da Vinci systems. In this study, we investigate the performance of a novel MicroHand SII robotic platform in patients with obesity. Methods From March 2018 to April 2019, a total of 7 patients whose BMI ranged from 29.9 to 49.8 kg/m2 were operated on with the robot-assisted technique using the MicroHand SII surgical system. Data regarding demography, surgical procedure and the 3-month outcome postoperation were collected. Results There were 2 female and 5 male patients with a median age (range) of 35 (20–51) years. The median operative time was 160 (149–195) minutes. None were converted to open surgery. All anthropometry indices improved significantly (p < 0.05) at 3 months postoperatively. There were no cases of surgical site infection, gastrointestinal/abdominal bleeding, or conversion to an open operation. Conclusions The initial experience showed that the Chinese domestic robot surgical system MicroHand SII could be feasibly and safely applied in sleeve gastrectomy in patients with obesity. Because of the unique design of this system such as a two-hand robot, an array of master–slave motion strategies, and a roll joint at the end of the instruments that allows 7 degrees of freedom, this robotic platform has presented its own obvious advantages.

Robot-assisted telesurgery can perform complex surgical manipulations from remote locations. Against the requirements of remote controlling for minimally invasive laparoscopic surgery robot, a prototype telesurgery system integrated on the existing ''MicroHand S'' robot was built. The prototype worked with the Internet, and a telesurgery communication protocol was set up based on Transmission Control Protocol/Internet Protocol. The stereo images of laparoscopy were transmitted by a hardware-based H.264 encoder/decoder. A demonstration environment of robotassisted remote minimally invasive surgery between the medical robot laboratory of Tianjin University and the visual surgery laboratory of the PLA Rocket Force General Hospital, which is about 150 km away, was set up. Control signal and laparoscope image transmission test between these two places were conducted. After the pegboard task and knot-tying task of phantom training, the first remote gall bladder removal surgery on the sow of China was successfully performed, on the basis of remote surgery robot system integration. The experimental results show that the developed prototype telesurgery system has enough remote control performance and operability for telesurgery.

Current surgical instruments with fewer degrees-of-freedom (DOF) for minimally invasive surgery (MIS) have limited capability to perform complicated and precise procedures, such as suturing and knot-tying. To address such a problem, a modular dexterous hand-held surgical robot with an ergonomic handle and 4DOF interchangeable instruments was developed. The kinematic arrangement of the instrument and that of the handle were designed to be the same. A compact roll-yaw-roll transmission was proposed applying cable-driven mechanism. Performance experiments were carried out to evaluate the effectiveness of the overall system. The measured grip forces of the robot ranged from 8.63 N to 19.18 N. The suturing performance score of the robot was significantly higher than that of the conventional instrument (28.8 ± 5.02 versus 17.2 ± 7.43, p = 0.041). The trajectory tracking test and animal experiment verified the accuracy and feasibility of the robot. The proposed robot could improve the surgical performance of MIS, providing various end-effectors and having an intuitive interface in the meantime.