Design of a novel two-DOF robotic active vibration suppression system based on dynamic decoupling and pose-dependent dynamics

Abstract

With the growing demands for industrial automation, robots have emerged as a cost-effective and highly integrative alternative to computer numerical control (CNC) machines for milling large and complex surfaces. However, the coupling vibrations and complex pose-dependent dynamic characteristics due to the low stiffness of industrial robots leads to serious vibration during machining, which severely impacts machining accuracy and quality. To address these challenges, this paper proposes a novel robotic active vibration suppression system including a two degrees of freedom electromagnetic dynamic vibration suppressor (EDVS) and the corresponding active vibration suppression controller. First, a two degrees of freedom active EDVS is designed for active vibration suppression, which suppresses vibrations by applying controlled forces to the robotic system during robotic milling. Then, the active vibration suppression controller, including control force dynamic decoupling strategy, Gaussian process regression (GPR), and time-varying linear quadratic regulator (LQR), is designed to ensure robust vibration suppression at different pose across the robot large workspace. The control force dynamic decoupling strategy is designed to eliminate coupling dynamic effects and independently design the controllers for each direction, the GPR model is developed to predict the robot pose-dependent modal parameters and the time-varying LQR is designed to realize adaptive pose-dependent gain updates. Finally, the effectiveness of the designed active vibration suppression system for robotic milling is verified through experiments, including long-path, high-speed offset-mass vibration suppression and actual milling experiments.