Prescribed Performance Bounded-H_∞ Control for Flexible-Joint Manipulators Without Initial Condition Restriction.

Area of Science:

• Robotics and Control Systems
• Advanced Manufacturing
• Aerospace Engineering

Background:

• Flexible-joint manipulators offer advantages like lightweight design and high flexibility, crucial for industrial, biomedical, and aerospace applications.
• The inherent flexibility of single-link flexible-joint manipulators (SLFJMs) presents significant control challenges, particularly concerning initial state limitations and robustness.
• Prescribed Performance Control (PPC) offers improved transient and steady-state performance but is often constrained by system initial states.

Purpose of the Study:

• To develop a novel prescribed performance bounded-H∞ fault-tolerant controller for SLFJMs.
• To overcome the limitations of existing PPC algorithms regarding system initial states and enhance control robustness.
• To ensure rapid convergence of tracking errors and smooth control input transitions.

Main Methods:

• Design of an improved tangent-type barrier Lyapunov function (BLF) to achieve initial-state-independent prescribed performance.
• Implementation of an input control function (ICF) to mitigate control input impulse responses and ensure smooth transitions.
• Development of a bounded-H∞ fault-tolerant control framework.

Main Results:

• The proposed controller demonstrates independence from the SLFJM's initial states, expanding the operational workspace and improving robustness.
• The improved tangent-type BLF facilitates rapid convergence of tracking errors to a small neighborhood around zero.
• Simulation experiments confirm the effectiveness and stability of the proposed prescribed performance bounded-H∞ fault-tolerant controller.

Conclusions:

• The developed controller effectively addresses the control challenges posed by SLFJMs, particularly concerning initial state dependency and fault tolerance.
• The novel approach enhances the practical applicability of flexible-joint manipulators by improving their workspace and control robustness.
• The proposed controller represents a significant advancement in the field of flexible-joint manipulator control.