Contouring Control of an Innovative Manufacturing System Based on Dual-Arm Robot

In this article, an innovative manufacturing system based on a dual-arm robot, each arm with five degree-of-freedom (DOF), is proposed. Although the proposed system can work in the automation mode or machining mode, only the function of machining is studied here. In this case, the system is equivalent to a five-axis machine tool. The method of equivalent errors is employed to design a robust contouring controller. It is shown that reducing the equivalent contour error in the joint space is equivalent to reducing both position contour error and tool orientation error in the task space. As a comparison, a conventional distributed controller is also designed. Several cases of experiments have been conducted, including a circular path with four different feedrates and an elliptic path. The experimental results show that the proposed method can achieve much better results in all cases, and demonstrate the feasibility of adopting the dual-arm robotic system for machining task.
Note to Practitioners
—This article was motivated by the traditional manufacturing system that is a cooperation between computer numerical controlled (CNC) machine tool(s) and robot arm(s). This article proposes a novel usage of a dual-arm robot with a fixed spindle and cutting tool in order to integrate the main functions of the CNC machine and robot arm together. This system alone can perform machining and automation tasks, which can significantly reduce the overall cost of a manufacturing system. The existing dual-arm robots have seldom been designed to perform machining tasks. For machining, a contouring controller is necessary and is proposed in this article. This model-based contouring controller relies on the accurate system parameters to achieve high precision machining. For example, the mass and inertia changes of a workpiece during machining should be considered. This issue will be addressed in our future research.