Fault tolerant adaptive control under actuator saturation for robot manipulators

Area of Science:

• Control Systems Engineering
• Robotics
• Mechanical Engineering

Background:

• Actuators face inherent limitations (bounded output, response discrepancies) often ignored by theoretical control.
• Ensuring safe and dependable operation requires reliable control techniques that address these practical constraints.

Purpose of the Study:

• To propose an adaptive control law for global regulation under partial loss of actuator effectiveness due to input faults.
• To maintain system configuration despite actuator physical limitations and unknown gravitational force parameters.
• To develop a robust control strategy capable of handling an infinite number of faults of arbitrary magnitude.

Main Methods:

• An adaptive control law is developed to account for actuator limitations and input faults.
• The control strategy treats inputs as time-varying signals, enabling robustness to uncertainties.
• Lyapunov's stability theory for non-autonomous systems is used to analyze the closed-loop system.

Main Results:

• The proposed control strategy maintains the system at the desired configuration under actuator faults.
• The control law is robust to unknown parameters in gravitational forces.
• Global asymptotic convergence of all signals is proven using Lyapunov stability theory.
• Simulations demonstrate resilience to degraded actuator performance.

Conclusions:

• The adaptive control law effectively manages actuator faults and limitations, ensuring system stability and performance.
• The methodology provides a theoretically sound approach to counteract arbitrary fault magnitudes.
• The strategy is suitable for real-world applications requiring robust and reliable actuator control.