Context-Dependent Compensation Scheme to Reduce Trajectory Execution Errors for Industrial Manipulators

Currently, automatically generated trajectories cannot be directly used on tasks that require high execution accuracies due to errors accused by inaccuracies in the robot model, actuator errors, and controller limitations. These trajectories often need manual refinement. This is not economically viable on low production volume applications. Unfortunately, execution errors are dependent on the nature of the trajectory and end-effector loads, and therefore devising a general purpose automated compensation scheme for reducing trajectory errors is not possible. This paper presents a method for analyzing the given trajectory, executing an exploratory physical run for a small portion of the given trajectory, and learning a compensation scheme based on the measured data. The learned compensation scheme is context-dependent and can be used to reduce the execution error. We have demonstrated the feasibility of this approach by conducting physical experiments.