永磁同步电机伺服系统的自适应模糊滑模控制

针对永磁同步电机伺服系统的跟踪控制问题,提出了一种基于扰动观测器的自适应模糊滑模控制方法.通过扰动观测器估计等效扰动,改善了系统的动态性能和稳态性能,并且只需要等效扰动的变化有界,而不是为零,放宽了要求;根据模糊控制原理引入3条模糊规则,在保证滑模条件的前提下有效地削弱了抖振;采用自适应策略估计模糊系统参数的最优值,简化了控制器的设计.实验结果表明,与常规自适应模糊滑模控制相比,本文提出的控制方法不仅能够有效地减小跟踪误差,而且能够改善参数估计过程,保证了参数估计的有界性.     

Simultaneous state and output disturbance estimations for a class of switched linear systems with unknown inputs

The paper considers the issues of state estimation and output disturbance reconstruction for a class of switched linear systems with unknown inputs. A singular switched system is derived from the original switched system by taking the output disturbance as a part of a new extended state vector. For the constructed singular switched system, a robust sliding-mode switched observer which can not only estimate the states of original switched system but also reconstruct output disturbances is proposed, where the switching of the observer is synchronous with that of the switched system. A sufficient condition is provided to guarantee the existence of the switched observer by the feasibility of an optimisation problem with linear matrix inequality constraint, and the corresponding switching signal with average dwell time is designed such that the convergence of the estimation error system is proven to be exponential. Based on the state estimation of singular switched system, the methods of state estimation and output disturbance reconstruction of original switched system are proposed. Finally, the simulation results confirm the predicted performance of the proposed methods.     

Observer‐based compensation control of servo systems with backlash

For compensating backlash phenomenon in servo systems, the authors propose an observer method in this paper to estimate both system states and vibration torque before controller design. First, a systematic scheme is given to obtain plant parameters, which is very important in observing system states. This is a parameter estimation principle that gives a crude estimation and computes the differences between the crude and true values. As a result, the precise value of the parameters is obtained by adding together the crude value and the difference. Then, based on the precise estimated parameters, an extended state observer (ESO) is designed to obtain feedback and feedforward signals. Consequently, robust compensation control is achieved by designing an output feedback controller, consisting of a feedback term and a feedforward term. Finally, in order to validate the proposed approach, extensive experiments are performed on a practical servo system with backlash nonlinearity.     

A disturbance observer design for backlash compensation

Electromechanical systems usually have an innate backlash in their gear trains which is normally nonlinear and limits the performance of the system. In this paper, a disturbance observer is designed in order to estimate the properties of the backlash. Generally, such disturbance observers are designed with the inverse model of the nominal plant but since the backlash is an internal factor of the plant, its effect cannot be separated from the system output. In the proposed model, the plant is reconfigured to separate the effects of the backlash from the output, and a new type of disturbance observer is proposed to detect and compensate for the backlash in the remodelled plant. The suggested disturbance observer is applied to the knee joint of a humanoid robot. Using the proposed disturbance observer, it is shown that the backlash can be compensated for, and that the tracking error decreases in the knee pitch trajectory. Also, an error analysis of the input trajectory is carried out to verify the performance of the proposed disturbance observer and the validity of the proposed control scheme is discussed.     

基于分数阶滑模控制技术的永磁同步电机控制

针对传统整数阶滑模控制系统中存在的抖震问题,本文提出了分数阶滑模控制策略并应用到永磁同步电机的速度控制.传统滑模控制器中的开关函数由作用在切换流型或其整数阶导数面推广到其分数阶导数面,利用分数阶系统的特性,缓慢地传递系统的能量,有效地削减抖震.本文采用模糊逻辑推理算法,实现软开关切换增益的自整定.仿真和实验证明,本文提出的分数阶滑模控制系统不但能有效地削减抖震,而且能保持滑模控制器对系统参数变化和外部扰动的鲁棒性.     

A supervisory fuzzy neural network control system for trackingperiodic inputs

A supervisory fuzzy neural network (FNN) control system is designed to track periodic reference inputs in this study. The control system is composed of a permanent magnet (PM) synchronous servo motor drive with a supervisory FNN position controller. The supervisory FNN controller comprises a supervisory controller, which is designed to stabilize the system states around a defined bound region and an FNN sliding-mode controller, which combines the advantages of the sliding-mode control with robust characteristics and the FNN with online learning ability. The theoretical and stability analyses of the supervisory FNN controller are discussed in detail. Simulation and experimental results show that the proposed control system is robust with regard to plant parameter variations and external load disturbance. Moreover, the advantages of the proposed control system are indicated in comparison with the sliding-mode control system     

状态约束下连铸结晶器振动位移系统的抗干扰控制

针对伺服电机驱动的连铸结晶器振动位移系统中存在的机械加工精度误差、摩擦非线性等不确定性和负载转矩扰动等问题,考虑伺服电机单方向变速转动产生的状态约束,提出了一种基于切换函数的抗干扰控制方案。首先,针对系统中状态约束且不可测及前向通道含有非线性周期函数（近似正弦函数,逆解非唯一）传递关系的问题,通过建立偏心轴转角误差与结晶器振动位移之间的函数关系,解决系统自身的状态约束问题。其次,针对系统存在的不确定性和负载转矩扰动问题,设计切换函数重构系统中存在的整体不确定性,通过扩张状态观测器对整体不确定性进行估计,将估计值与滑模控制方法相结合设计输出反馈控制器,实现结晶器振动位移的跟踪控制。最后,通过Lyapunov理论证明了控制系统的稳定性,通过仿真验证了本文所提方法的有效性。     

Optimal Output Feedback Controllers for Spacecraft Attitude Tracking

This paper investigates the problem of output feedback attitude tracking control of a rigid spacecraft in the presence of external disturbances. Two optimal control laws with a disturbance estimator are developed to deal with this problem. An adapted extended state observer is used to estimate the angular velocity tracking errors and to allow for compensation for the total disturbances. The proposed control can be expressed as the sum of a nonlinear optimal controller and an estimated disturbance. For the optimal controller, the state‐dependent Riccati equation and optimal Lyapunov techniques are employed to solve the infinite‐time nonlinear optimal control problem. The developed controllers can minimize a performance index and ensure the stability of the closed‐loop system and external disturbance attenuation. On the other hand, using the adapted extended state observer, the asymptotic convergence of estimation error dynamics is proven. An example of multiaxial attitude manoeuvres is given and simulation results are included to demonstrate and verify the usefulness of the proposed controllers.     

自抗扰控制和高频信号注入的内嵌式永磁同步电机无位置传感器控制

针对内嵌式永磁同步电机无位置传感器控制系统,基于自抗扰控制技术和高频信号注入技术,提出了以转子位置角为扩张状态观测器(extended state observer,ESO)主体变量的自抗扰控制系统.该方法避免了传统算法中以电流为ESO主体变量时依靠角速度估计值积分来获得转子位置角估计值所带来的误差积累问题.该方法在电机起动、负载突变等电流波形正弦度较差的情况下,仍能保证转子位置角的估计值具有较高的精度.仿真结果验证了所提出方法的正确性和优越性.