| With the development of the times and the progress of science and technology, robotictechnologies also bring forth the new through the old. Traditional rigid robots use hardmaterials and have limited degrees of freedom, thus it is difficult for them to meet thegrowing requirements of security and flexibility. In addition, due to their large workspaceand poor compliance, rigid robots also can not be applied to narrow and crowdedunstructured environment. In this context, soft robots come into being. The initialinspiration of soft robots comes from living things in the nature. Through observing andstudying the structure of the mammalian tongue, elephant nose and octopus tentacles,researchers find physiology and motion mechanisms that animals change their shapes andsizes to adapt to different environments and tasks, and then make use of them for designand development of soft robots.Compare with rigid robots, discrete hyper-redundant robots and hard continuumrobots, the main advantage of soft robots is in material. Most of soft robots are made offlexible materials, and the flexibility and continuity they own make them have infinitedegrees of freedom, which not only ensure security, but also improve flexibility, thereforesoft robots can move freely in complicated structured and unstructured environment. All ofthe above-mentioned characteristics make soft robots particularly suitable for applicationssuch as minimally invasive surgery, exploration and rescue.Although soft robots have advantages that other types of robots can not match, but it is undeniable that there are still many technical problems in the field of soft robots, andthey have severely restricted practical application. Among them the most prominent pointsare, firstly, to establish accurate kinematic and dynamic models, and secondly, to achieveprecise motion control.In accordance with ablation in cardiac minimally invasive surgery, a cable-driven softrobotic manipulator system is set up, and then kinematic and dynamic models of softrobotic manipulator are presented, afterwards an adaptive visual servo controller isdesigned, at last validity of the models and controller are verified by experiments. Ablationfor cardiac surgery in minimally invasive surgery, designed a line drive flexiblemanipulator system, the establishment of a flexible manipulator kinematics and dynamicsmodel adaptive visual servo controller, model and verified by experimentand theeffectiveness of the controller. The main contents and innovations of this paper aresummarized as follows:1. Design a cable-driven soft robotic manipulator system. The soft roboticmanipulator made of silicone rubber, and has no rigid structure inside. Thoughpulling the cables by actuation system, the soft robotic manipulator will rotateand bend in a certain degree.2. Establish kinematic model of the soft robotic manipulator. Based on piecewiseconstant curvature hypothesis, three spaces namely actuation space, virtual jointspace, task space and two mappings namely actuation space-virtual joint spacemapping, virtual joint space-task space mapping are established to obtain therelationship between the length variables of4cables and the position andorientation of the soft robotic manipulator end-effector.3. Establish dynamic model of the soft robotic manipulator. Based on Lagrange mechanics, analyse kinetic energy, gravitational potential energy and elasticpotential energy of each segment, and compute total kinetic energy and potentialenergy using integration. As a result, Lagrange equation of the soft roboticmanipulator is obtained, and finally we convert it to a general form of dynamics.4. Design an adaptive visual servo controller. Based on depth-independent imageJacobian matrix, kinematics-based and dynamics-based visual servo controller ispresented. The controller use adaptive algorithm to estimate unknown position ofthe feature point in the base coordinate system, and then asymptotic stability ofthe controller is proved by Lyapunov theory. |
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