Practical torque tracking control of electro-hydraulic load simulator using singular perturbation theory.

Area of Science:

• Control Engineering
• Fluid Power Systems
• Robotics

Background:

• Electro-hydraulic systems exhibit complex nonlinear dynamics due to coupled mechanical and hydraulic components.
• Advanced control algorithms are often limited by these nonlinearities and high-order characteristics.
• Accurate torque tracking is crucial for applications like electro-hydraulic load simulators.

Purpose of the Study:

• To develop a robust and accurate torque tracking control strategy for electro-hydraulic load simulators.
• To address the challenges posed by the double-dynamics of mechanical and hydraulic subsystems.
• To enhance the applicability of advanced control algorithms in electro-hydraulic systems.

Main Methods:

• Application of singular perturbation theory to decompose the system into slow (mechanical) and fast (hydraulic) subsystems.
• Development of an active disturbance rejection control (ADRC) with desired model compensation for the slow mechanical system.
• Implementation of a proportional control law for the fast hydraulic system.
• Theoretical stability analysis using the extended Tikhonov's theorem.

Main Results:

• The proposed controller ensures exponential stability for the slow mechanical subsystem.
• The fast hydraulic subsystem is demonstrated to be exponentially stable with the proportional controller.
• The overall closed-loop system stability is theoretically validated.
• Experimental results confirm the effectiveness of the presented control scheme.

Conclusions:

• The singular perturbation-based approach effectively manages the double-dynamics of electro-hydraulic systems.
• The combination of ADRC and proportional control provides high accuracy and robustness.
• The validated control scheme significantly advances torque tracking capabilities in electro-hydraulic load simulators.