Improving robotic machining accuracy by real-time compensation

Although robotics based flexible automation is considered as an ideal solution for foundry pre-machining operation, very few successful installations have been seen due to many major challenges involved in robotic machining processes using conventional articulated robot, such as limited material removal rate, low surface quality, and chatter/vibration. This paper explains the reasons for low surface quality in robotic machining processes and analyzes the stiffness properties of robot structure. Then a real-time compensation algorithm based on a robot stiffness model and force control scheme is introduced. The experimental results show that much better surface quality can be achieved without extending the process cycle time.