Sliding mode control for offshore parallel antenna platform with large orientation workspace.

Area of Science:

• Robotics and Control Systems
• Mechanical Engineering
• Aerospace Engineering

Background:

• Offshore antenna platforms require precise trajectory tracking for optimal performance.
• Stewart-type parallel mechanisms offer large orientation workspaces but present control challenges.
• Accurate estimation of platform posture and limb velocities is crucial for effective control.

Purpose of the Study:

• To propose a novel sliding mode control strategy for trajectory tracking of offshore antenna platforms.
• To develop a posture compensation algorithm for comprehensive parameter acquisition.
• To design a state observer for limb velocity estimation and a robust controller to mitigate chattering.

Main Methods:

• A posture compensation algorithm utilizing azimuth and elevation data.
• A super-twisting algorithm-based state observer for limb velocity estimation.
• A modified nonsingular terminal integral sliding mode controller with a higher-order super-twisting algorithm.
• Lyapunov stability theory for controller validation.

Main Results:

• The proposed control strategy effectively solves the trajectory tracking problem for offshore antenna platforms.
• The controller significantly reduces chattering through the higher-order super-twisting algorithm.
• Stability of the proposed control system is rigorously proven using Lyapunov theory.
• Simulations show superior performance compared to three other controllers, with a 49.49% reduction in the integral of squared error.

Conclusions:

• The novel sliding mode control strategy offers superior trajectory tracking performance for offshore antenna platforms.
• The integrated posture compensation and state observer enhance the system's ability to handle complex movements.
• The proposed method provides a robust and stable solution, outperforming existing control techniques.