倾转伺服故障下倾转三旋翼无人机的滑模被动容错姿态控制设计

Sliding Mode-Based Passive Fault-Tolerant Attitude Control Design for a Tilt Trirotor UAV under Tilt Servo Failures

摘要: 倾转旋翼无人机因其独特的气动外形及复杂的倾转伺服机构，在执行器故障方面表现出比传统多旋翼无人机更高的脆弱性。针对垂直起降(VTOL)飞行模式下倾转伺服机构故障导致的姿态控制问题，本文提出了一种基于快速非奇异终端滑模的被动容错姿态控制方法(FNTISM)。该方法在快速非奇异终端滑模控制的基础上引入积分环节，以消除倾转伺服机构卡死故障引起的稳态跟踪误差，并采用单位四元数描述姿态运动，避免了欧拉角描述在大角度机动时的万向节锁定问题。基于Lyapunov稳定性理论，证明了所设计控制器能够保证姿态跟踪误差在有限时间内收敛到零。仿真结果表明，在倾转伺服机构卡死故障情况下，所提出的FNTISM控制器相较于传统滑模控制(SMC)和快速非奇异终端滑模控制(FNTSM)，具有更快的收敛速度、更小的超调量以及无稳态误差的优越控制性能，显著提升了倾转旋翼无人机在故障工况下的鲁棒性。

Abstract: Tilt trirotor unmanned aerial vehicles (TTRUAVs) exhibit greater vulnerability to actuator failures compared to conventional multi-rotor UAVs due to their unique aerodynamic configuration and complex tilt servo mechanisms. To address the attitude control problem caused by tilt servo mechanism failures in vertical take-off and landing (VTOL) flight mode, this paper proposes a passive fault-tolerant attitude control method based on fast nonsingular terminal sliding mode (FNTISM). An integral term is introduced into the fast nonsingular terminal sliding mode control to eliminate the steady-state tracking error induced by tilt servo jamming failures. Meanwhile, unit quaternion is employed to describe the attitude kinematics, avoiding the gimbal lock problem associated with Euler angle representation during large-angle maneuvers. Based on Lyapunov stability theory, it is proven that the designed controller can guarantee finite-time convergence of the attitude tracking error to zero. Simulation results demonstrate that, under tilt servo jamming failure conditions, the proposed FNTISM controller achieves superior control performance with faster convergence speed, smaller overshoot, and zero steady-state error compared to conventional sliding mode control (SMC) and fast nonsingular terminal sliding mode control (FNTSM), significantly enhancing the robustness of tilt-rotor UAVs under failure scenarios.