基于速度观测的双余度电液舵机系统容错同步控制

考虑飞机电液舵机活塞杆运动速度不易测量的情况，提出一种基于速度观测的容错同步控制策略，解决了双余度电液舵机系统（DREHAS）内泄漏共模故障（IL-CMF）下的位置跟踪控制问题。首先，通过引入2组参考轨迹并对模型进行线性变换，实现舵面位置跟踪与两舵机力输出同步控制解耦；其次，在扩展状态观测器（ESO）中加入故障参数自适应项，设计一种自适应扩展状态观测器（AESO）估计两通道舵机活塞杆速度和扰动，从而克服了故障条件下利用原系统模型设计ESO带来的估计结果不准确问题；最后，基于AESO的估计结果及故障参数在线更新结果，利用反步法设计了一种非线性容错同步控制器。Lyapunov稳定性分析结果表明，该控制方法可确保IL-CMF故障及时变干扰条件下，闭环系统所有信号有界，系统输出满足规定的性能要求。IL-CMF故障及常值干扰条件下，系统跟踪误差渐进收敛于零。仿真实验进一步验证了所提方法的有效性。 

Fault-tolerant synchronization control for a dual redundant electro-hydraulic actuator system based on velocity estimation

Considering the fact that the piston velocity measurements of electro-hydraulic actuators are not available in practice, a fault-tolerant synchronization control strategy based on piston velocity estimation is proposed to deal with the positon tracking problem for a Dual Redundant Electro-Hydraulic Actuator System (DREHAS) suffering from Internal Leakage Common-Mode Fault (IL-CMF) and disturbances. First, by introducing two groups of reference trajectory and a linear transformation of the system states, the decoupling of the control surface position tracking and the two actuators output force synchronization control is realized. Second, an Adaptive Extended State Observer (AESO) is designed to estimate the piston rod velocities and disturbances of the two-channel actuators, which overcomes the inaccuracy of the estimation results of Extended State Observer (ESO) under fault condition. Finally, based on the state estimation and the online adaptation of faulty parameters, a nonlinear fault-tolerant synchronization controller is developed by employing backstepping method. Lyapunov stability analysis indicates that the proposed scheme can ensure that all the signals of the closed-loop system are bounded and the system can achieve a prescribed tracking performance under IL-CMF and time-varying disturbances. Moreover, the system tracking error converges to zero asymptotically in the present of IL-CMF and constant disturbances. A simulation experiment validates that the proposed control scheme is effective.