Adaptive Fault Tolerant Tracking Control for Output Constrained Nonlinear Systems Using a Novel BLF Method
提出一种新型正切型非对称障碍李雅普诺夫函数，结合命令滤波和反步法，为具有预定义时变输出约束和未知执行器故障的非线性系统设计了自适应容错跟踪控制器，释放了初始值要求，并通过实例验证了有效性。
In this work, via proposing a novel <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\tan $ </tex-math></inline-formula>-type asymmetric barrier Lyapunov function (ABLF), we developed a command filtered adaptive fault tolerant control scheme for a class of uncertain nonlinear systems with predefined-time asymmetric and time-varying output constraints. First, such a class of constraints under interest is more practical. Unlike most of the existing constraints that need to be addressed at the moment of inception, the initial value requirement of the constrained object in this work is released. A predefined setting time can be installed in advance through the implementation of a shifting function embedded within the proposed ABLF. Second, the problem of unknown actuator faults is considered where the actuator faults can be both multiplicative and additive. Third, by combining the command filter and backstepping techniques, a twice-transformation design method is presented to construct the desired controller, under which the errors between the virtual control laws and the outputs of the command filters can be compensated thoroughly. Aside from avoiding the “explosion of complexity” issue, the designed controller also achieves the requisite tracking performance. Meanwhile, under such controller, the effect of the actuator faults can be estimated. Finally, the validity of the given scheme is evaluated through the use of a practice example.