On Digital Implementation of Resonant Extended State Observer-Based Control

A resonant extended state observer-based control (RESOBC) was digitally implemented for a class of plants subjected to narrow-band disturbances. To achieve an efficient compensation of narrow-band disturbances, the RESOBC was designed to have resonant poles that are very sensitive to digital realization. Inappropriate discretization can cause pole deviation, severely degrading narrow-band disturbance rejection performance. In addition to the resonant poles, some other critical performance, such as tolerance to the sampling time, stability margin, and disturbance rejection capability, should be considered when discretizing. To satisfy these requirements, first, various digital implementation methods were proposed. Next, the theoretical analyses of the resonant poles and observability were performed to help select effective methods. For these selected methods, comprehensive comparisons were conducted to investigate the differences in the other critical performance. The results can be used as guidelines for the application of RESOBC.