WPT Based Compression for Bilateral Control

This paper introduces a codec scheme for compressing control and feedback signals especially for bilateral control systems. The method uses a low pass filter and Wavelet Packet Transform (WPT) for coding and Inverse Wavelet Packet Transform (IWPT) for decoding. Data compression is handled in low pass filter output by reducing sampling rate; and in high pass filter output by reducing wavelet outputs. Codec works on both data paths, which flows between a master system and a slave system over a networked control architecture. With the proposed scheme, a greater percent of the compressed data can be recovered using the same compression rate. It is confirmed that the controller using compressors and decompressors performs similarly as the uncompressed one while enabling transmission of much less data over network. The viability of the proposed scheme is proven by experiments on a single-DOF motion control system controlled over network. Proposed method is also compared with a benchmark method which uses DFT for compression.