Kinematic modeling and inverse kinematics solution of a new six-axis machine tool for oval hole drilling in aircraft wing assembly

Abstract

Automatic oval hole machining is a great challenge in monolithic wing assembly of aircraft. In this paper, a new six-axis machine tool for oval hole drilling in aircraft wing assembly is developed, and an efficient kinematic modeling and inverse kinematics method for six-axis machine tools is proposed. After a brief structure analysis, necessary coordinate systems are established to build the generalized kinematic model of the six-axis machine tool. Then, with the concept of separation and combination, an inverse kinematics strategy for six-axis machine tools is proposed to improve the accuracy, efficiency, and stability of the algorithm. All motion axes are separated into three groups and their joint coordinates are solved successively based on the joints separation strategy (JSS) for solution. Finally, the inverse kinematic solution of the six-axis machine tool is composed of the prismatic joints with analytical solutions, revolute joints with analytical solutions, and revolute joints with numerical solutions. To verify the validity of the proposed method, numerical and machining experiments have been performed on the developed six-axis machine tool. In the simulation, two error vectors for joint coordinates and the pose of tool tip are presented to evaluate the accuracy of the inverse kinematics algorithm. The simulation results show the great success of the proposed method. Moreover, the position and orientation errors of the drilled oval holes are within 0.093 mm and 0.408°, which is accurate enough to meet the requirement for automatic oval hole machining in aircraft assembly.