A Novel Fixed-Time Super-Twisting Control with I&I Disturbance Observer for Uncertain Manipulators

Area of Science:

• Robotics
• Control Systems Engineering
• Applied Mathematics

Background:

• Traditional sliding mode control (SMC) suffers from chattering and uncontrollable convergence times.
• Uncertain robotic arm systems require robust control strategies for precise trajectory tracking.

Purpose of the Study:

• To develop a novel fixed-time super-twisting sliding mode control (ST-SMC) strategy for uncertain robotic arm systems.
• To address chattering and establish a bounded convergence time for robotic arm control.
• To enhance robustness and achieve high-precision tracking.

Main Methods:

• Constructed a sliding surface with fixed-time convergence characteristics.
• Designed an immersion and invariance (I&I) disturbance observer for real-time estimation of disturbances.
• Developed a new ST-SMC controller based on the disturbance observer for global fixed-time convergence.

Main Results:

• Achieved fixed-time convergence of tracking errors regardless of initial conditions.
• Effectively eliminated control torque chattering.
• Attained a high tracking error accuracy of 2 × 10^-9.

Conclusions:

• The proposed ST-SMC strategy ensures fixed-time convergence and suppresses chattering in uncertain robotic arms.
• The method demonstrates applicability and robustness for high-precision robotic systems.
• Explicitly bounded convergence time enhances predictability and reliability in robotic control.