Research On Force-free Control And Collision Detection Technology Of Orthopedic Robot

With the advantages of smaller wound surface,shorter recovery time and more precise operation,orthopedic surgery robots have received widespread attention in the medical field.However,the problems of complex operation of orthopedic surgery robots and the safety of doctors and patients cannot be guaranteed are not completely solved,so reducing the operation difficulty of orthopedic surgery robots,improving the positioning accuracy of orthopedic surgery robots and ensuring the safety of surgery are the top priorities for further promotion of orthopedic surgery robots.Based on the circumstance,this paper adopts zero-force control technology and collision detection strategy to investigate the unitary compliance and safety of the orthopedic surgery robots.Research contents and conclusions include the following aspects:(1)Kinematics and dynamics simulation and analysis of orthopedic surgery robot.The kinematics model of the self-developed 5-axis orthopedic surgery robot was constructed based on MDH method,and the forward and inverse kinematics analysis and Jacobian matrix derivation were carried out.The correctness of forward and inverse kinematics and the rationality of workspace were verified by using MATLAB robot toolbox.The dynamic equation of orthopedic surgery robot was deduced based on Newton Euler method,and the correctness of the dynamic modeling of orthopedic surgery robot was verified by ADAMS simulation platform.(2)Research on force-free control of robot joints.Compared and analyzed the two realization methods of force-free control,combined with the requirements of this topic,finally determined the force-free control based on torque control,and then proposed the parameter identification method of gravity term and friction term.Aiming at the friction model in the robot joint system,the Lu Gre model is used and a Lu Gre friction parameter identification method based on the OBL-SAMPSO algorithm is proposed,and the SIMULINK simulation shows that the proposed OBL-SAMPSO algorithm reduces the overall error by an average of 85.86%compared with the traditional PSO algorithm.On this basis,a single joint compliant drag experimental platform based on Twin CAT3 is built.The experimental surface shows that the force-free control algorithm proposed in this paper has good flexibility.(3)Research on robot joint collision detection.The robot joint collision moment observer is constructed based on the generalized momentum.The advantage of this method is that the robot collision detection can be realized only by reading the driving torque and position information of the motor,and the sudden collision detection can be realized by analyzing and optimizing the generalized momentum observer.A discretization algorithm was adopted considering the collision detection algorithm in practical application.Collision detection based on generalized momentum observer is implemented on a single joint experimental platform,and the feasibility of the optimized algorithm is verified.(4)Research on the overall compliant dragging technology of orthopedic surgery robot.Considering the orthopedic surgery robot with load operation,the load dynamics model of orthopedic surgery robot was established,and the correctness of the load dynamics of orthopedic surgery robot was verified based on ADAMS simulation platform.The zero-force control co-simulation of orthopedic surgery robot was built based on ADAMS and SIMULINK.The simulation results showed that the drag force was far less than the torque that the human arm could improve,which verified the feasibility of the zero-force drag control algorithm of orthopedic surgery robot.(5)Research on the overall collision detection strategy of orthopedic surgery robot.Global collision detection of orthopedic surgery robot based on generalized momentum observer.Three kinds of post-collision safety strategies are proposed for post-collision processing.On this basis,ADAMS and SIMULINK are used to complete the co-simulation of collision detection of orthopedic surgery robot,which verifies the feasibility of collision detection of orthopedic surgery robot based on momentum observer,and analyzes the influence of gain coefficient on observer.The larger K_r value is,the smaller K_s value is.The impact moment estimated by the improved momentum observer is closer to the actual external impact moment.