Kinematics Modeling And Performance Optimization Of Valve Spraying Robot

According to the actual requirements of pipeline valve with curved surface and the narrow space for spraying,the 6R serial robot configuration with non-spherical wrist for spraying is presented.The forward kinematics model of the robot is established,the pose parameters of the wrist relative to the reference coordinate system,so that the forward kinematic parameters are obtained.Due to the analytic solution for inverse kinematics of the serial robot with non-spherical wrist has not been found,the ADAMS software is used to simulate the kinematics.The curves of the joints' rotations are drawn when the trajectory of the end-effector is given,so that the numerical solution of the inverse kinematics is obtained.Considering for the complexity and narrowness of the valve body,the forward and inverse kinematics of the non-spherical wrist are solved.The size and shape of robot workspace is an important indicator of the kinematic performance.Two numerical methods for solving the robot workspace are proposed: Monte Carlo stochastic search method and integrated simulation method based on Matlab/SimMechanics software.The principle of Monte Carlo method is that the instantaneous value of the joint angle is randomly assigned in the reasonable range,the positions of the end point of the robot are determined by forward kinematics model,finally these points gather in the point cloud of the workspace.The principle of integrated simulation based on Matlab/SimMechanics software is to build the robot model using SimMechanics library.The sensor in the model can track and get the instantaneous position of the robot's execution module(the end point of the arm).The robot workspace can be drawn out according to a large number of end-point data.The results shows that these two methods are similar to each other,which verifies the reasonableness.Furthermore,the method based on SimMechanics is better than Monte Carlo method in the sharpness of the figure and the numerical calculation accuracy,but for multiple degrees of freedom,redundancy and joint under limited circumstances which is difficult to solve the analytical solution of the robot,Monte Carlo method overcomes the defects of the robot working space by degrees of freedom limitation,the analytical method is simple and suitable for solving engineering problems.In this paper,a method of random sampling joint instantaneous rotation angle is proposed,which transforms the continuous pose of the serial robot into a series of discrete pose in the workspace.The inverse of the condition number of the Jacobian/Hessian matrix is proposed in the whole workspace.The approximation method of the value approximates the theoretical exact solution of the performance index by means of the sampling points of the large sample.Based on the above method,the kinematic global performance index and the global performance fluctuation index of the serial robot are solved,and the range of the scale parameter of the mechanism with excellent global kinematic performance and small fluctuation can be determined.Simulation results of the kinematic parameters of the robot show that the motion of the robot is more stable and the control precision is higher,which proves the rationality and validity of the proposed method.Aiming at the automatic spraying process of pipeline valve,the whole layout scheme of double-station production line with automatic valve spraying is presented.The 3D model of the automatic spraying production line is set up using SolidWorks,and then it is simulated in ADAMS software.The simulation results show that the displacement of the end point,the joint angle and angular velocity of the robot are reasonable,and range in regular without break,which can ensure the stability of spraying.The research can provide the important theoretical reference for the following fabrication and debugging for the prototype.Finally,the prototype experiment is carried out to verify the feasibility of the automatic spraying line,which provides an important theoretical reference for subsequent automatic spraying instead of manual spraying.