Robust fixed-time sliding mode controller for flexible air-breathing hypersonic vehicle.

Area of Science:

• Aerospace Engineering
• Control Systems Theory
• Nonlinear Control

Background:

• Flexible air-breathing hypersonic vehicles (FAHV) face challenges from actuator faults and nonlinear dynamics.
• Robust control is essential for maintaining stability and performance in such complex systems.
• Existing control methods may struggle with fast convergence and fault tolerance.

Purpose of the Study:

• To develop an improved robust fixed-time sliding mode controller (RFSMC) for FAHVs with actuator faults.
• To enhance fault-tolerant capabilities and reduce chattering.
• To achieve fast and precise convergence of the system states.

Main Methods:

• Input/output feedback linearization of the FAHV nonlinear model.
• Design of a novel non-singular fast fixed-time integral sliding surface (FFIS).
• Utilizing a continuous fixed-time super-twisting-like reaching law (CFSTL) and a uniformly convergent observer.

Main Results:

• The proposed FFIS and CFSTL ensure fixed-time convergence of the sliding mode vector and its derivative.
• The uniformly convergent observer accurately estimates lumped disturbances.
• Simulations demonstrate the effectiveness and superiority of the RFSMC in handling actuator faults and attenuating chattering.

Conclusions:

• The RFSMC offers enhanced fault-tolerant performance for FAHVs.
• The controller achieves fast and precise system response with reduced chattering.
• The proposed control strategy is effective for complex hypersonic vehicle dynamics.