Adaptive Output Feedback Control for a Class of Uncertain Stochastic Nonlinear Systems With Unknown Time‐Delays

This paper investigates the problem of output feedback control for a class of stochastic nonlinear systems with time‐delays. Using dynamic gain scaling technique, an adaptive update law is introduced to the observer and controller to deal with the unknown parameters. Based on the Lyapunov‐Krasovskii functional and stochastic Barbalat's lemma, it is proved that the proposed universal‐type adaptive output feedback controller can regulate all the states of the closed‐loop system almost surely. A simulation example is presented to illustrate the effectiveness of the proposed design procedure.     

未知离散非线性系统的鲁棒自适应NN控制

利用WNN(小波神经网络)逼近未知函数，将未知离散非线性系统转化为一类参数化严格反馈系统，进而对变换后的系统给出一个避免过参数化的自适应反推控制器，并证明该控制器可保证在存在参数不确定性和函数不确定性的条件下，整个自适应系统的状态全局有界，同时也可保证系统的跟踪误差落在一个大小与不确定性成比例的紧集中，仿真结果表明该控制器具有较强的鲁棒性，可适用于不同的对象。     

Adaptive Fuzzy Output Tracking Control of MIMO Nonlinear Uncertain Systems

In this paper, the adaptive fuzzy tracking control problem is discussed for a class of uncertain multiple-input-multiple-output (MIMO) nonlinear systems with the block-triangular structure. The fuzzy logic systems are used to approximate the unknown nonlinear functions. By using the backstepping technique, the adaptive fuzzy tracking control design scheme is developed, which has minimal learning parameterizations. The adaptive fuzzy tracking controllers guarantee that the outputs of systems converge to a small neighborhood of the reference signals and all the signals in the closed-loop system are semiglobally uniformly ultimately bounded. Two examples are used to show the effectiveness of the approach     

参数不确定非线性系统的自适应控制和鲁棒控制

研究一类参数不确定非线性系统的非自适应鲁棒控制及自适应控制问题。通过引入二人零和对策得到非自适应鲁棒控制律，并与参数估计结合得到自适应控制律。证明了参数估计有界和收敛时闭环系统Ｌｙａｐｕｎｏｖ稳定性和渐近稳定性。仿真结果说明了该方法的有效性及具体实现方法。     

一类非线性不确定系统的鲁棒自适应控制

针对一类含有未知参数和动态不确定的非线性系统,基于Lyapunov递推设计方法设计了状态反馈控制器,并提出了鲁棒自适应控制算法。所设计的控制器不仅可保证闭环系统的全局稳定性。而且使得系统对于所有允许的不确定系统状态全局一致终值有界。仿真结果表明了本文方法所设计的控制器的有效性和可行性。     

Adaptive Fixed-time Output Feedback Tracking Control for Uncertain Nonlinear Systems

International Journal of Control, Automation and Systems - This article studies the fixed-time output feedback tracking control based on the command filtered backstepping method for nonlinear...     

Adaptive Neural Tracking Control for Unknown Output Feedback Nonlinear Time-delay Systems

An adaptive output feedback neural network tracking controller is designed for a class of unknown output feedback nonlinear time-delay systems by using backstepping technique.Neural networks are used to approximate unknown time-delay functions.Delay-dependent filters are intro- duced for state estimation.The domination method is used to deal with the smooth time-delay basis functions.The adaptive bounding technique is employed to estimate the upper bound of the neural network reconstruction error.Based on Lyapunov-Krasoviskii functional,the semi-global uniform ultimate boundedness(SGUUB)of all the signals in the closed-loop system is proved.The arbitrary output tracking accuracy is achieved by tuning the design parameters and the neural node number. The feasibility is investigated by an illustrative simulation example.     

NN-Based Adaptive Tracking Control of Uncertain Nonlinear Systems Disturbed by Unknown Covariance Noise

A class of uncertain nonlinear systems that are additionally driven by unknown covariance noise is considered. Based on the backstepping technique, adaptive neural control schemes are developed to solve the output tracking control problem of such systems. As it is proven by stability analysis, the proposed controller guarantees that all the error variables are bounded with desired probability in a compact set while the tracking error is mean-square semiglobally uniformly ultimately bounded (M-SGUUB). The tracking performance and the effectiveness of the proposed design are evaluated by simulation results.     

一类非线性时滞大系统的自适应鲁棒控制

研究一类包含参数不确定性和关联时滞的不确定时滞组合大系统的鲁棒控制问题。利用线性矩阵不等式技术和自适应参数估计方法,设计鲁棒自适应控制器,从而保证闭环系统渐近稳定。最后给出了仿真示例,说明了该方法的有效性。     

A New Robust Adaptive Control of Uncertain Nonlinear Systems and Pendulum Application

A new robust adaptive control of uncertain nonlinear systems is proposed in this paper. The proposed method combines sliding mode control with the immersion and invariance (I&I) adaptive scheme, and it has more available degrees of freedom than using the backstepping scheme. Via the proposed method, a class of nonlinear systems with mismatched parametric perturbations can be rendered asymptotically stable and the performance of the system can also be improved. Finally, the proposed method is applied to a simple pendulum with motor dynamics, and simulation results show the effectiveness and performance of the proposed method.     

Adaptive Output Feedback Control for Switched Stochastic Nonlinear Systems with Time-varying Parameters and Unknown Output Functions

International Journal of Control, Automation and Systems - In this paper, we discuss the adaptive output feedback control problem for switched stochastic nonlinear systems which involve uncertain...     

Indirect Adaptive Fuzzy Output Feedback Control with Supervisory Controller for Uncertain Nonlinear Systems

In this paper, an indirect adaptive fuzzy output feedback controller with supervisory mode for a class of unknown nonlinear systems is developed. The proposed approach does not need the availability of the state variables, moreover, a supervisory controller is appended to the adaptive fuzzy controller to force the state to be within the constraint set. Therefore, if the adaptive fuzzy controller cannot maintain the stability, the supervisory controller starts to work to guarantee stability. On the other hand, if the adaptive fuzzy controller works well, the supervisory controller will be de-activated. The overall adaptive fuzzy control scheme guarantees the stability of the whole closed-loop systems. The simulation results confirm the effectiveness of the proposed method.     

Robust Output Tracking for MIMO Nonlinear Time-Varying Mismatched Uncertain Systems Via Hybrid Control Strategy

This paper considers the problem of robust output tracking control for multi-input multi-output (MIMO) nonlinear systems in the presence of mismatched time-varying uncertainties. Using singular perturbation method and variable structure control technique, we derive a new hybrid controller for MIMO systems with unknown time-varying uncertainties and disturbances to track a desired trajectory. It is shown that the hybrid controller not only stabilizes the closed-loop systems, but also guarantees the tracking errors remain in an O() neighbourhood of the origin where is a small design parameter of the controller. Moreover, by selecting the parameter properly, the tracking errors can be made arbitrarily small.     

含约束的非线性不确定系统的鲁棒控制

讨论一类含约束的非线性不确定系统的鲁棒控制问题（这里的不确定性并不要求满足匹配条件）。在一定的假设条件下给出了使该类问题可解的充分条件，构造出相应的鲁棒控制器，该控制器避免了利用微分几何方法所得控制器易产生过度控制的缺点。     

Robust Adaptive Fuzzy Control of Nonlinear Systems with Unknown and Time‐Varying Saturation

In this paper, a robust adaptive fuzzy control approach is proposed for a class of nonlinear systems in strict‐feedback form with the unknown time‐varying saturation input. To deal with the time‐varying saturation problem, a novel controller separation approach is proposed in the literature to separate the desired control signal from the practical constrained control input. Furthermore, an optimized adaptation method is applied to the dynamic surface control design to reduce the number of adaptive parameters. By utilizing the Lyapunov synthesis, the fuzzy logic system technique and the Nussbaum function technique, an adaptive fuzzy control algorithm is constructed to guarantee that all the signals in the closed‐loop control system remain semiglobally uniformly ultimately bounded, and the tracking error is driven to an adjustable neighborhood of the origin. Finally, some numerical examples are provided to validate the effectiveness of the proposed control scheme in the literature.     

Robust Adaptive Control of Feedback Linearizable MIMO Nonlinear Systems With Prescribed Performance

A novel robust adaptive controller for multi-input multi-output (MIMO) feedback linearizable nonlinear systems possessing unknown nonlinearities, capable of guaranteeing a prescribed performance, is developed in this paper. By prescribed performance we mean that the tracking error should converge to an arbitrarily small residual set, with convergence rate no less than a prespecified value, exhibiting a maximum overshoot less than a sufficiently small prespecified constant. Visualizing the prescribed performance characteristics as tracking error constraints, the key idea is to transform the ldquoconstrainedrdquo system into an equivalent ldquounconstrainedrdquo one, via an appropriately defined output error transformation. It is shown that stabilization of the ldquounconstrainedrdquo system is sufficient to solve the stated problem. Besides guaranteeing a uniform ultimate boundedness property for the transformed output error and the uniform boundedness for all other signals in the closed loop, the proposed robust adaptive controller is smooth with easily selected parameter values and successfully bypasses the loss of controllability issue. Simulation results on a two-link robot, clarify and verify the approach.     

一类不确定非线性系统的自适应鲁棒控制

针对一类由非线性微分方程描述的不确定单输入单输出(SISO)系统,提出了一种自适应鲁棒控制算法.设计了一动态滤波器并将其与原系统组成扩展系统,由滤波器求得控制律稳定扩展系统.算法绕开辨识模型参数而是直接估计函数值,加快了控制律的求解.设计了状态误差观测器,用观测器的值构造控制律逼近状态反馈时的控制效果.基于Lyapunov 稳定理论分析了扩展系统的渐近稳定性并给出了闭环稳定的充分条件.最后仿真结果验证了算法的有效性和鲁棒性.     

Event-based Adaptive Output Feedback Prescribed Performance Control for a Class of Switched Nonlinear Systems with Unknown Control Directions

International Journal of Control, Automation and Systems - An event-triggered adaptive tracking control problem is investigated for a class of switched nonstrictfeedback nonlinear systems with...     

一类不确定非线性系统的鲁棒控制

提出一种新的适于不确定非线性系统的鲁棒控制方案。它对系统的不确定性的知识要求较少,因而能处理一大类不确定非线性系统的控制问题。其另一个优点是能有效克服[1]中方案在过渡响应阶段产生的过大控制信号问题。