Kinematic modeling and base frame calibration of a dual-machine-based drilling and riveting system for aircraft panel assembly.

The paper introduces a new automatic drilling and riveting system for aircraft panel assembly which is composed of two five-axis machines in coordination. Kinematic modeling and base frame calibration are fundamental problems for the dual-machine system to improve its positioning accuracy. In this paper, a comprehensive kinematic model for the dual-machine system is established based on the modularization concept, and a new base frame calibration method is proposed which consists of the direct calibration based on laser tracker and calibration error compensation based on a specially designed instrument. In the kinematic modeling stage, the kinematic model of the dual-machine system is divided into three parts and three corresponding sub-models are established. With the pose constraints of coordinated machines, a comprehensive kinematic model of the dual-machine system is built. In the base frame calibration stage, the base frames of dual machines are firstly established by laser tracker. Due to many error sources in the calibration process, the relative pose errors of dual machines exist with the relationship between the base frames of coordinated machines. Then, the calibration error is measured by a specially designed instrument and used to modify the primary base frame calibration results. To verify the validity of the proposed method, experiments have been performed and the results have shown great improvement in base frame calibration accuracy. With the advantage of easy operation and high accuracy, this method can be extended to other multi-machine and multi-robot systems. [ABSTRACT FROM AUTHOR]