An Interpolator, Providing High Accuracy of Industrial Robot’s End-Effector Speed. Part II

Abstract

The interpolator is one of the critical components of industrial robots control, significantly affecting their accuracy. In such technological tasks as welding, laser cutting, coating, and surfacing, in addition to the spatial accuracy of the robot’s endeffector, the accuracy of its velocity during motion along complex trajectories plays an important role. In this paper, we propose a new approach for solving the interpolation problem of a multi-axis industrial robot based on the B-splines. The proposed algorithms can be easily adapted for robots with any kinematics, generating the current, velocity, and position setpoints for the control loops of each of its actuators. A software implementation of the offline interpolator based on the proposed algorithms was developed and executed on B&R industrial controllers. During the experimental studies performed on a SCARA robot, it was demonstrated that the developed algorithmic solutions outperform the standard interpolator of B&R control systems, exceeding it up to 2 times in terms of spatial accuracy and up to 4 times in terms of root mean square velocity deviation. The maximum deviation of the tool’s velocity using the developed algorithms did not exceed 2.4 mm/s, comparable to the results of the most modern planar solutions based on NURBS curves. At the same time, unlike their planar analogs, the solutions proposed in this paper are suitable for multidimensional interpolation. This part is devoted to simulation and field experimental studies of the algorithms described in Part I of this paper, as well as a summary of the the research results