No abstract

Recently, robot manipulators have been adopted to perform machining tasks, instead of only automation tasks. The key machining task is to follow a desired contour. Therefore, the machining accuracy can be improved by reducing contour error. However, only a few researches concentrate on solving the contouring problem in the robotic machining system. In this paper, a model predictive control (MPC)‐based contouring control scheme is proposed for a machining system based on a 5‐DOF dual‐arm robot. The contouring control problem is transformed into the regulation problem by using the method of equivalent errors. An MPC algorithm is developed to minimize the contour error by optimizing a sequence of control actions under torque constraints. In addition, robustness is upgraded by integral sliding mode control (ISMC). Experiments are carried out for the proposed methods and two other conventional methods. The results show that the proposed control scheme can achieve much better contouring performance than the conventional methods, indicating the effectiveness of the proposed controller.

Cycle time minimization is one of the major goals that many manufacturers are eager to achieve. Maximizing feedrate is the direct solution, however, physical motions need to be under the specified motion limits to avoid high-frequency vibration, causing machining error. In this paper, a time-optimal feedrate scheduling approach for 5-axis G1 toolpath is presented for 5-axis machining. A quintic B-spline corner smoothing method is utilized to smoothen sharp corners in the toolpath. Then, the S-shape feedrate profile of each block is optimized under the actuator motion constraints, with the objective of minimizing the cycle time. Particle swarm optimization (PSO) is used to provide the optimized solution. Experiments are conducted to validate the proposed approach and the results are compared with two other existing approaches. It is found that the proposed method can achieve shorter cycle time and less contour errors, showing the effectiveness of the proposed approach.

No abstract

Cycle time minimization is one of the major goals that many manufacturers are eager to achieve. Maximizing feedrate is the direct solution, however, physical motions need to be under the specified motion limits to avoid high-frequency vibration, causing machining error. In this paper, a time-optimal feedrate scheduling approach for 5-axis G1 toolpath is presented for 5-axis machining. A quintic B-spline corner smoothing method is utilized to smoothen sharp corners in the toolpath. Then, the S-shape feedrate profile of each block is optimized under the actuator motion constraints, with the objective of minimizing the cycle time. Particle swarm optimization (PSO) is used to provide the optimized solution. Experiments are conducted to validate the proposed approach and the results are compared with two other existing approaches. It is found that the proposed method can achieve shorter cycle time and less contour errors, showing the effectiveness of the proposed approach.