Trajectory Generation of an Industrial Robot with Kinematic and Dynamic Variations for Improving Positional Accuracy

Abstract

To improve the robot efficiency, the main thing is to increase the accuracy of the end-effect or pose of the robot arm manipulator. There are many uncertainties which will hamper the performance of the industrial robot arm. The uncertainties which influence the end-effect or position are working environments, kinematic parameters and dynamic parameters variation, measurement errors and the installation errors. Of these uncertainties the kinematic parameter and dynamic parameter variations can be controlled by the user to reduce the end-effect or positional error. The kinematic parameters are position, velocity and acceleration whereas the dynamic parameters are the torque and torque rate. Smooth trajectory for any path can be constructed by limiting these kinematic and dynamic parameters variations of the industrial robot arm. Acceleration continuity is necessary for the robot arm to reduce the jerk in the manipulator which otherwise induces vibrations in the manipulator that causes deviation in the encoders which results in end-effect or positional variation of the manipulator. So by constraining the acceleration, torque of the manipulator by constructing a cubic spline trajectory to achieve smooth trajectory is done in the present work. The work in the present project is done by considering the 6-DOF Kawasaki RS006L. Multi objective constrained optimization of the trajectory is done using Non-dominated Sorting Genetic Algorithm (NSGA-II). MATLAB 2015b is used for all the calculations and plotting the graphs. The jerk and torque values before and after optimization are plotted.