Stability Analysis and Quantitative Tuning of Modified Uncertainty and Disturbance Estimator-Based Control for a Class of Time-Delay Processes

Modified uncertainty and disturbance estimator (MUDE) based control shows great robustness against unexpected dynamics in the presence of time delay. Although effective in several applications, the stability is not theoretically guaranteed and the controller tuning is still challenging. The resulting control performance highly depends on the specialized expertise. To this end, this article analyzes the stability in terms of the scaled controller parameters, and proposes a unified quantitative tuning rule for a MUDE structure for a class of first-order time-delay process model (including open loop stable, integrating and unstable time delay processes). The stable regions of the MUDE parameters are theoretically derived. The influence mechanism of the scaled filter parameter and feedback gain on the disturbance rejection (DR) response is analyzed in detail, and then used to determine the feedback gain. Exhaustive robustness testings reveals that the delay margin is a critical index for controller tuning. A unified, robust and quantitative tuning rule is concluded as well as an explicit retuning guideline. Some comparison simulations and laboratory experimental are conducted to demonstrate the efficiency of the proposed tuning rule.

Automated summary

This article proposes a modified uncertainty and disturbance estimator (MUDE) based control method that exhibits strong robustness against unexpected dynamics in the presence of time delay. By adjusting the MUDE parameters, stable control of a class of first-order time-delay process models can be achieved. The stable regions of the MUDE parameters are theoretically derived and the influence mechanism of the filter parameter and feedback gain on disturbance rejection response is analyzed. The research findings highlight the criticality of delay margin in controller tuning.