Active disturbance rejection control with fractional-order model-aided extended state observer

Area of Science:

• Control Engineering
• Nonlinear Control Systems
• Fractional Calculus

Background:

• Active disturbance rejection control (ADRC) enhances disturbance rejection via extended state observers (ESO).
• High observer bandwidth in ESO improves performance but amplifies noise, degrading control quality.
• Existing ADRC methods face challenges in balancing disturbance rejection and noise suppression.

Purpose of the Study:

• To propose a novel fractional-order ADRC (FOADRC) to overcome the limitations of traditional ADRC.
• To design a fractional-order model-aided extended state observer (FOMESO) for improved disturbance estimation.
• To reduce noise sensitivity and enhance overall control performance.

Main Methods:

• Designed a fractional-order model-aided extended state observer (FOMESO) utilizing plant information.
• Transformed a second-order plant into a fractional-order double-integrator model.
• Developed a FOADRC controller without a noise-sensitive derivative component.

Main Results:

• FOMESO improved disturbance estimation under a given observer bandwidth without aggravating noise sensitivity.
• The FOADRC scheme demonstrated superior performance over traditional ADRC in tracking, noise sensitivity, disturbance rejection, and stability.
• The proposed FOADRC exhibited robustness to plant parameter variations.

Conclusions:

• The proposed FOADRC, utilizing FOMESO, offers enhanced control performance and robustness.
• The method effectively mitigates noise issues associated with high observer bandwidths in ADRC.
• Experimental validation on a permanent magnet synchronous motor confirms the FOADRC's superiority and effectiveness.