Dual-drive Anti-backlash And Synchronous Control System Design Of A Large-span Crossbeam

Vertical picture-frame jig is often adopted in the outer wing box assembly of large aircrafts. In order to provide an installation foundation for wing box leading edge locators and make the vertical hoisting of large wing box components easier,a movable large-span crossbeam structure is needed in the wing box digital assembly system. Because of the heavy load and the high synchronous and positioning precision requirements of the large-span crossbeam system, the difficulties on the motion control system designing are extraordinarily large. Aiming at the synchronous control problem of the large-span movable crossbeam with two axes driven by rack and pinion in the wing box digital assembly system of a large aircraft, this paper presents a position closed loop control system with gantry synchronization coupled by dual-drive anti-backlash, and the accurate synchronous movement of the large-span crossbeam is achieved. The main contents of the paper are as follows:The wing box digital assembly system of a large aircraft is described on components and functions, and the mechanical structure and drive system of the large-span crossbeam are designed in details, and based on the summary of the functions of the crossbeam system, the synchronous control problem of the large-span crossbeam with two axes driven by rack and pinion is proposed, and the designing indexes and basic control strategies of the crossbeam system are present.The dynamic model of the large-span crossbeam drive system is set up,and a position closed loop control system with gantry synchronization coupled by dual-drive anti-backlash is presented based on the model. On the basis of the software realization of dual-drive anti-backlash system, a bias current controller is designed to achieve the dynamic adjustment of bias current, and an adaptive friction observer is proposed to compensate the unknown and varying friction of the crossbeam system.The simulation studies are carried out to verify the effectiveness of the presented controllers.The hardware and software of the large-span crossbeam system are described in details, the controllers are established using the Mechaware toolbox, and then the experimental research is carried out to verify the effectiveness of the proposed controllers. The experimental results indicate that the positioning accuracy and repeat positioning accuracy of the large-span crossbeam are 0.017mm and 0.003mm respectively,and the tracking error of single axis and synchronous error of two axes under the maximum velocity of 40mm/s are 0.05mm and 0.011mm respectively. So the experimental indexes are satisfied and the effectiveness of the proposed controllers is verified.Finally, the research work of this paper is summarized thoroughly, and the future research is prospected.