Research on the control of the suspension stiffness for the beams in Gantry Machining Center

The requirement of the stiffness of the magnetic suspension beams in Large Gantry Machining Center is different from that of the magnetic suspension trains and other magnetic suspension devices. According to its characteristics, a kind of suspension technology, which combines the permanent magnet and the electromagnetism together, is presented and could obviously reduce power consumption. In order to solve the impact of the change of current in magnet coils on the overall stiffness, a double closed loop control system, which introduces a current loop into the position loop for forming a position and current double closed loop control system, is adopted. According to the process characteristics of the machine tool and the choice of parameters in the controller as the fuzzy control rules, a genetic algorithm (GA) fuzzy PID controller to meet the requirement of suspended beams on the machine tool is designed. The simulation results show that the fuzzy PID controller using the GA can increase the stiffness of the suspension system to meet the precision requirement of the magnetic suspension beams system on the machine tool. The optimization effect of the GA is very outstanding, which makes the choice of every parameter in fuzzy PID controller more comprehensive and scientific.