Fixed-time sliding mode composite control with prescribed performance for uncertain Stewart parallel mechanism...

Area of Science:

• Robotics
• Control Systems Engineering
• Applied Mathematics

Background:

• Stewart parallel mechanisms (SPMs) face challenges in precise task-space tracking due to disturbances and uncertainties.
• Existing control methods often struggle to balance transient response, steady-state accuracy, and energy efficiency.

Purpose of the Study:

• To develop an advanced control strategy for improving the tracking control performance of SPMs in task space.
• To address disturbances and uncertainties while ensuring fast, non-overshoot transient response and high steady-state accuracy.
• To reduce control energy consumption in SPM systems.

Main Methods:

• Design of a fixed-time adaptive sliding mode disturbance observer (FxTASMDO) to handle lumped uncertainties.
• Implementation of an asymmetric hyperbolic cosecant prescribed performance function to constrain tracking errors.
• Development of a fixed-time sliding mode control with prescribed performance (FxT-SMCC-PP) by integrating the observer and control law.

Main Results:

• The proposed FxT-SMCC-PP method achieves fast transient response without overshoot.
• High steady-state tracking accuracy is maintained even under disturbances and uncertainties.
• Significant reduction in control energy consumption was observed.
• Validation through simulation and prototype experiments confirmed the method's effectiveness.

Conclusions:

• The FxT-SMCC-PP offers a robust and efficient solution for enhancing SPM tracking control.
• The integration of fixed-time control, adaptive sliding modes, and prescribed performance is effective.
• This approach provides a promising direction for advanced parallel robot control applications.