Synchronization control of dual-drive system in gantry-type machine tools based on disturbance observer

Precise synchronization motion control has always been a problem need to be solved in the gantry-type NC machine tools (GNCMT) with a dual-drive system. The complexity of the system puts forward a great challenge for the setting of the PID controller parameters. In addition, one of the key elements which seriously affects the synchronization precision of the dual-drive system is disturbance. To realize the precise synchronization control, a mathematical model of the dual-drive system which combined with the mechanical coupling model of the gantry mechanism and the model of transmission system of each axis was presented firstly. And then, model parameters were identified based on Least Square(LS) method. In order to reduce the effects of friction and eccentric disturbance on the synchronization performance and improve the anti-interference performance of the system, a synchronization control strategy based on disturbance observer (DOB) which used the identified model as the nominal model was proposed. Finally, a simulation analysis was carried out. The simulation results showed that the synchronization performance of dual-drive system in GNCMT is obviously improved through the disturbance compensation.