基于观测器的控制时滞线性系统的最优跟踪控制

研究了控制时滞线性系统的二次型最优跟踪控制问题.首先将控制时滞系统转化为无时滞系统,再将最优跟踪问题转化成等价系统的最优调节问题.然后,通过求解Riccati方程,设计含动态观测器的前馈-反馈最优跟踪控制律,利用构造参考输入观测器解决了前馈补偿器的状态物理不可实现问题.仿真实例验证了所设计的最优跟踪控制律的有效性.     

基于神经网络的学习控制及其在机器人中的应用

针对一类非线性系统的跟踪控制问题 ,首先提出了一种遗忘因子迭代学习控制算法 ,给出了算法收敛的充分条件 ,然后 ,利用神经网络原理 ,对要求跟踪的新的期望轨迹 ,在系统的历史控制经验基础上 ,用神经网络估计系统的期望控制输入 ,然后将其作为迭代学习控制器的初始控制输入 ,再由迭代学习律逐步改善控制输入 ,使系统的实际输出只需较少的迭代次数就能达到跟踪的精度要求。机器人系统的仿真结果表明了该算法的有效性。     

基于粒子滤波前馈补偿的电机伺服系统控制

针对电机轨迹跟踪过程的非线性非高斯噪声，提出采用基于粒子滤波的前馈控制器。同时对电机伺服系统提出一种二自由度控制结构，基于闭环系统的鲁棒最优性能指标，设计给定值状态目标跟踪控制器，根据系统稳态运行时的抗扰动要求，在过程输入和控制对象输入之间设计前馈控制器、在对象输入和输出端之间设计负载干扰抑制闭环，利用粒子滤波的方法消除非高斯噪声对控制系统的干扰。仿真实例验证了该控制系统的可行性和优越性，可以有效提高电机轨迹跟踪精度。     

永磁直驱风力发电系统最大功率跟踪非线性抗扰控制

针对永磁同步发电机的非线性、内部参数不确定以及外部扰动等问题,提出了一种直驱式永磁同步风力发电系统最大功率跟踪的非线性抗扰控制方法。该方法使用一种非线性光滑函数来设计非线性扩张状态观测器(NLESO)和非线性抗扰控制律。由NLESO来实现系统扰动及不确定性的估计,前馈到控制输入端对扰动进行补偿,从而有效提高了系统的抗扰能力。分析了NLESO的收敛性。仿真结果表明了该控制方法不仅具有响应速度快、控制精度高的特点,而且无超调无抖振现象,因而在风力发电系统最大功率跟踪控制领域具有较大应用价值。     

电流型PWM整流器的自适应动态面控制

利用前馈解耦方法,将电流型PWM整流器在同步坐标系下的多输入多输出非线性模型分解为2个单输入单输出的非线性模型。采用动态面控制方法对2个单输入单输出模型分别设计了非线性控制器,并结合自适应技术对负载电阻进行了估计。动态面方法通过引入一阶滤波器,避免了在设计控制器过程中对虚拟控制律的求导计算。仿真结果表明,系统运行在单位功率因数下,直流输出电流可以快速跟踪参考信号,验证了该控制策略的正确性和有效性。     

风力发电系统最大功率跟踪自适应鲁棒控制

为了提高风力发电系统最大功率跟踪(MPPT)运行的工作性能,针对系统未知建模误差和外部扰动等不确定问题,提出了一种MPPT自适应鲁棒控制方法。该方法建立在基于广义扰动的风力发电系统角速度跟踪动态模型基础上,不依赖于系统模型参数和外部扰动辨识。利用MPPT跟踪偏差的非线性状态反馈和扰动边界值的在线实时估计,自适应地调整切换控制项增益,以加快系统收敛的速度。实际控制律经过一阶积分输出,进一步削弱控制输出信号幅值的抖振,平滑发电转矩,提高跟踪精度。通过构造Lyapunov函数,验证了闭环系统的全局稳定性。通过与常规线性PID控制和非线性动态状态反馈控制(SFC)进行仿真比较,验证了该控制器实现最大功率跟踪控制的良好效果,具有较强的鲁棒性和自适应性。     

基于自适应模糊滑模控制的机器人轨迹跟踪算法

针对控制参数的不确定性以及存在未知外部扰动情况下移动机器人的轨迹跟踪问题,提出一种基于光滑非线性饱和函数的自适应模糊滑模轨迹跟踪控制算法。通过建立不确定非线性移动机器人运动控制模型,利用自适应模糊逻辑系统构建自适应模糊滑模控制器。为了增强轨迹跟踪控制算法对随机不确定外部扰动适应能力的同时削弱滑模控制算法中的输入抖振现象,利用有界输入有界输出(BIBO)稳定的方法,通过带有自适应调节算法的模糊系统对滑模控制律中非线性函数项进行自适应逼近,并设计了模糊系统中可调参数的自适应控制律,保证了控制系统的稳定与收敛。实验结果表明,所设计的控制器对系统参数不确定性和外界扰动均具有较强的轨迹跟踪性能和鲁棒性。与传统的滑模控制算法相比,该算法不仅能有效减小输入抖振而且轨迹跟踪控制精度提高了18.89%。     

前馈型电压模式控制逆变器

在传统电压模式基础上,对单相全桥逆变器提出了一种前馈型电压模式控制方案,利用开关变换器稳态输入/输出占空比关系构造控制方程,引入输入电压前馈使得输入电压波动对输出无影响,同时在无积分反馈环节下输出电压就能稳定跟踪参考信号,避免了PID控制中积分项对系统性能的影响,控制实现上则采用输入电压积分电路求解控制方程中的开关占空比。进行了性能分析并与传统PID控制逆变器的模型比较,理论分析表明前馈型电压模式控制逆变器具有稳态跟踪性能好、抗输入电压扰动以及对负载跳变动态响应好的优点。仿真对比和实验验证的结果表明理论分析的正确性和前馈型电压模式控制的有效性。所提控制方案具有控制简单、模拟电路容易实现的优点,便于实际应用。     

基于动态扩展算法的大型燃煤机组非线性协调控制系统设计

为了从根本上解决单元机组在大范围变工况时的协调控制问题，克服非线性特征对系统控制品质的影响，论文应用反馈线性化原理，对大型燃煤机组的协调控制问题进行了直接非线性控制的研究。针对被控对象的特点，引入相对阶向量的动态扩展算法，得到了单元机组简化非线性模型的输出反馈控制律，该控制律可以实现全局意义下的精确反馈线性化，对线性化变换有定义的整个区域都是适用的；针对反馈线性化律作用下的伪线性系统，设计了二自由度I-PD控制结构，简单而有效地解决了伪线性系统对扰动敏感、鲁棒性差的问题，确保输出变量的精确跟踪。通过比较系统闭环传递函数与期望传递函数的对应项系数，可以方便整定出控制器参数。求得的控制器由比例或积分环节构成，形式简单，便于工程实现。在500MW燃煤机组非线性模型上的仿真试验证明了该协调控制系统的负荷跟踪能力、抗干扰性能及鲁棒性。     

具有可测干扰非线性系统的前馈/反馈线性化

研究了一类具有可测干扰的非线性系统的线性问题。在基于输出对控制输入的相对阶基础上,应用于输出对于干扰输入的相对阶概念,给出了一个非线性前馈／状态反馈变换律,与系统的结构特性有关,变换律可能是静态的也可能是动态的,从而可以基本消除可测干扰对系统输出的影响,并且在闭环系统中得到了一个线性输入输出的关系,最后给出了计算实例来证明所提变换律的有效性。     

Nonlinear Optimal Internal-Model Control for Multiple Time-Delay Systems with Application to Vehicle Suspensions

Abstract

The paper considers the nonlinear optimal vibration control problem for systems with multiple delays, i.e. control delay, state delay, and measurement delay, under reference input. The time-delay system is transformed into an equivalent delay-free one via functional transformations. The nonlinear optimal control law is designed by solving a Riccati equation, a Sylvester equation, and an adjoint differential equation. The effects generated by nonlinearity and time-delay are compensated by the nonlinear compensator and the memory terms in the designed controller. An internal model is constructed so that the disturbance will be rejected with zero steady-state error as well as the reference is tracked, through the dynamical compensator produced from the internal model. An observer is constructed to make the controller physically realizable. The result is extended to vehicle suspension systems. It is demonstrated that the road vibration that is encountered by the suspension will be canceled entirely by the proposed control. Numerical simulations illustrate the effectiveness of the presented controller.     

轨迹跟踪伺服系统的鲁棒复合控制

针对控制输入饱和受限且带有未知扰动的电机伺服系统,提出一种实现曲线轨迹准确跟踪的鲁棒复合控制方案。该方案引入一个参考信号生成器和一个扩展状态观测器,其中参考信号生成器可根据目标轨迹信号构造出对应的状态量,扩展状态观测器用于对系统的状态量和扰动进行估计,采用反馈与前馈相结合构成最终的控制律。利用Lyapunov理论对闭环系统的稳定性进行了严格分析。在MATLAB中进行了仿真研究,随后在一个DSP控制的永磁直线电机二维伺服平台进行了试验验证。结果表明:所提的控制方案能在轨迹跟踪任务中取得优越的瞬态性能和稳态准确性,而且对目标轨迹和扰动的幅值差异具有较好的鲁棒性。     

基于干扰观测器的永磁同步直线电机自适应PID控制

针对永磁同步直线电机精确速度跟踪的问题,提出一种基于干扰观测器的自适应PID控制器。针对基于矢量控制的直线电机模型设计非线性干扰观测器进行干扰观测。同时,基于李雅普诺夫稳定性设计超限补偿控制器以及在线更新的投影自适应律使PID控制律始终跟随反馈控制律。最后通过试验分析结果,证明了该控制策略有更好的动态性能及鲁棒性。     

Tracking control for nonlinear time-delay multiagent systems with input saturation

In this paper, the tracking control problem for a class of nonlinear time-delay multiagent systems with input saturation is considered. The nonlinear dynamics are dominated by strict-feedback form and satisfy Lipschitz conditions with constant gains. First, it indicated that the tracking control problem is equivalent to a general bound problem of high-dimensional multivariable systems. Second, an ingenious state transformation is utilized to change the bound problem into the parameter design problem. Third, by the static gain control technique and the hyperbolic tangent function, both state feedback and output feedback controllers are built such that all signals of the closed-loop systems are globally bounded, and the tracking errors between the followers and the leader can converge to a small neighborhood around the origin by appropriately selecting parameters. Finally, an example is shown to verify the feasibility of our results.     

Sliding mode disturbance observer‐based adaptive control for uncertain MIMO nonlinear systems with dead‐zone

In this paper, an adaptive integral sliding mode control (ISMC) scheme is developed for a class of uncertain multi‐input and multi‐output nonlinear systems with unknown external disturbance, system uncertainty, and dead‐zone. The research is motivated by the fact that the ISMC scheme against unknown external disturbance and system uncertainty is very important for multi‐input and multi‐output nonlinear systems. The system uncertainty, the unknown external disturbance, and the effect of dead‐zone are integrated as a compounded disturbance, which is well estimated using a sliding mode disturbance observer (SMDO). Then, the adaptive ISMC based on the designed SMDO is presented to guarantee the satisfactory tracking performance in the presence of system uncertainty, external disturbance, and dead‐zone. Finally, the designed adaptive ISMC strategy based on SMDO is applied to the attitude control of the near space vehicle, and simulation results are presented to illustrate the effectiveness of the proposed adaptive ISMC scheme using the SMDO. Copyright © 2016 John Wiley & Sons, Ltd.     

Integral barrier Lyapunov function-based adaptive fuzzy output feedback control for nonlinear delayed systems with time-varying full-state constraints

In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods.     

Adaptive multi-dimensional Taylor network funnel control of a class of nonlinear systems with asymmetric input saturation

In view of the result and performance of control are affected by the existence of input constraints and requirements, adaptive multi-dimensional Taylor network (MTN) funnel control problem is studied for a class of nonlinear systems with asymmetric input saturation in this paper. Firstly, the effect of asymmetric input saturation can overcome by introducing the Gaussian error function, namely, the asymmetric saturation model is represented as a simple linear model with a bounded disturbance. Secondly, MTNs are employed to approximate the unknown functions in the controller design. Then, an adaptive MTN tracking controller is developed by blends the idea of funnel control into backstepping, which can guarantee that the tracking error always meets the given prescribed performance regarding the transient and steady state responses as well as the output of system tracks the give continuous reference signal. Finally, the effectiveness of the proposed control is demonstrated using two examples.     

Robust output tracking of uncertain nonlinear time‐delay systems with unknown dead‐zone inputs via control schemes with a simple structure

The adaptive robust output tracking control problem is considered for a class of uncertain nonlinear time‐delay systems with completely unknown dead‐zone inputs. A new design method is proposed so that some adaptive robust output tracking control schemes with a rather simple structure can be constructed. It is not necessary to know the nonlinear upper bound functions of uncertain nonlinearities. In fact, the constructed output tracking control schemes are structurally linear in the state and have a self‐tuning control gain function that is updated by an adaptation law. In this paper, the dead‐zone input is nonsymmetric, and its information is assumed to be completely unknown. In addition, a numerical example is given to describe the design procedure of the presented method, and the simulations of this numerical example are implemented to demonstrate the validity of the theoretical results.