High-Precision Control for a Stewart Platform With Prescribed Disturbance-Rejection Performance

Area of Science:

• Robotics
• Control Systems Engineering
• Mechatronics

Background:

• Stewart platforms are complex robotic systems susceptible to external disturbances.
• Effective disturbance rejection is crucial for maintaining precision and stability in Stewart platform operations.
• Existing control methods may not offer guaranteed performance bounds or rapid convergence for disturbance estimation.

Purpose of the Study:

• To introduce and validate a novel prescribed-performance-controller-based equivalent-input-disturbance (PEID) approach.
• To enhance the disturbance-rejection capabilities of Stewart platforms.
• To ensure disturbance-estimation error converges within a prescribed time and to a user-defined small bound.

Main Methods:

• Development of a PEID control strategy tailored for Stewart platforms.
• Stability analysis using a subsystem decomposition and barrier Lyapunov functions.
• Design of a compensator and an algorithm for state feedback and observer gains.
• Experimental validation on a physical Stewart platform.

Main Results:

• The PEID approach ensures disturbance-estimation error converges to a pre-defined bounded region within a prescribed time.
• The control system demonstrates superior disturbance-rejection performance compared to existing methods.
• Experimental results confirm the effectiveness and practical applicability of the PEID method.

Conclusions:

• The proposed PEID approach significantly improves disturbance rejection in Stewart platforms.
• Prescribed performance for disturbance estimation error is achievable, offering enhanced control precision.
• The PEID method provides a robust and effective solution for controlling Stewart platforms in the presence of disturbances.