Trajectory tracking controller of high precise positioning system based on iterative learning control with wavelet filtering method

For those objects with repeated motion characteristics such as IC (integrated circuit) packaging, iterative learning control (ILC) offers a good scheme for achieving the positioning control of high precise and high dynamic response by eliminating the effect of repetitive disturbances. However, in actual production, the increasing improvement of IC chip integration level makes IC packaging technology tend to be highly integrated and multilead, every working condition has to be learned individually, which will seriously affect the learning efficiency. Moreover, the existed nonrepetitive disturbances reduce the effect of ILC. In order to improve the learning efficiency in IC packaging operations of different pins, this paper proposes an iterative learning controller with wavelet filtering method to eliminate the dependence of iterative learning feedforward on the initial positions of different trajectory conditions. Through the wavelet analysis of the tracking errors with two different starting points, corresponding wavelet coefficients are obtained separately. Then by means of adjusting the wavelet coefficients, the nonrepetitive disturbance part related to the positions are removed, thus acquiring a universal feedforward sequence unrelated to positions, which can be used for various trajectory tracking. At last, the effectiveness of the proposed method has been demonstrated with the experimental results of a voice coil motor actuating positing system.