High accuracy motion control of linear motor drive wire-EDM machines

This paper is aim to develop and investigate a permanent magnet linear-motor-driven table system for a wire-EDM machine. Dynamic model and system identification of the linear motor system have been derived and analyzed. The linear motor drive system has nonlinear and time-varying behaviors because of the effect of irregular friction of the sliding surface and cogging force. Therefore, a conventional digital controller may not suffice to provide a high contouring accuracy as well as adequate disturbance rejection and parameter variation robustness. An indirect adaptive controller (IAC), combined with a neural network-based feedforward controller (NNBFC) is proposed to improve contouring performance of the linear motor system. Experimental results show that this control method achieves satisfactory contouring accuracy under the influence of friction and cogging force.