On the Implementation of a Wavelet-based Iterative Learning Controller Using CPLD/FPGA

The realization of a wavelet-based iterative learning controller (WILC) is presented in this paper. To meet the requirements of simplified hardware, fast rapid prototyping and fast up-date cycle, a wavelet-based iterative learning control system is implemented on a single FPGA (Field Programmable Gate Array) . There are three modules in this FPGA-based system, they are a feedback module, a discrete wavelet transform (DWT) module and an inverse discrete wavelet transform (IDWT) module. An external static random access memory (SRAM) is also employed to store the learning control signal processed by wavelet transform before updating the feedback control signal. To verify its effectiveness, a belt-driven ink-jet printer is adopted as the control target and a much improved speed-tracking performance is observed from the experimental verification. With the help of the learning process, the ink-jet printer needs no calibration during continuous operation and the velocity of the printer-head can be steadily running at 24 inch/sec.