Fault-Tolerant Control Strategies for Robotic Manipulators

Fault-tolerant control (FTC) for robotic manipulators seeks to maintain safe and accurate operation in the presence of actuator faults, sensor failures or unmodelled disturbances. Modern strategies combine fault diagnosis, estimation and reconfiguration to detect abnormalities and adjust control laws in real time. Central to many schemes is sliding mode control, prized for its robustness against matched uncertainties and capacity for finite-time convergence. Recent advances integrate high-order sliding mode observers to estimate both system states and fault magnitudes, disturbance observers to compensate unknown dynamics, and adaptive or neural network elements to relax the need for precise models. Active FTC architectures monitor performance online, trigger reconfiguration upon fault detection and ensure stability via Lyapunov-based proofs. Passive FTC designs embed robustness within a single controller, trading optimal performance for simplicity. Emerging research also explores synchronisation techniques to share information across multi-joint systems and reduce cumulative error under cascading faults. These developments underpin fault-resilient robots in manufacturing, surgery and field service, enhancing safety, reliability and uptime in critical applications.

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Fault-Tolerant Control Strategies for Robotic Manipulators publication trend

The graph below shows the total number of articles in fault-tolerant control strategies for robotic manipulators across all publications each year (not limited to Nature Index journals).

Technical terms

Fault-tolerant control (FTC): A control paradigm that maintains system stability and performance despite faults in actuators, sensors or subsystems.

Sliding mode control (SMC): A robust control technique that forces system trajectories onto a designed manifold, offering resilience to matched uncertainties and finite-time convergence.

Disturbance observer (DO): An algorithm that estimates unknown inputs or model errors in real time, allowing the controller to compensate disturbances actively.

Finite-time convergence: A property by which system errors reach zero within a pre-specified time bound, enhancing responsiveness in critical applications.

Chattering: High-frequency oscillations in sliding mode control output, often mitigated by higher-order schemes or smoothing laws.

References

1. An Adaptive Neural Non-Singular Fast-Terminal Sliding-Mode Control for Industrial Robotic Manipulators. Applied Sciences (2018).
2. Fault Diagnosis and Fault‐Tolerant Control of Uncertain Robot Manipulators Using High‐Order Sliding Mode. Mathematical Problems in Engineering (2016).
3. A Non-Singular Fast Terminal Sliding Mode Control Based on Third-Order Sliding Mode Observer for a Class of Second-Order Uncertain Nonlinear Systems and its Application to Robot Manipulators. IEEE Access (2020).
4. A Novel Fault-Tolerant Control Method for Robot Manipulators Based on Non-Singular Fast Terminal Sliding Mode Control and Disturbance Observer. IEEE Access (2020).
5. Implementation of Fault-Tolerant Control for a Robot Manipulator Based on Synchronous Sliding Mode Control. Applied Sciences (2020).