Continuous adaptive control with zero hysteresis constant and no chatter

In this paper, we examine the application of the well-known hysteresis switching algorithm of adaptive control in the case of a continuously parameterised set of candidate controllers. Subject to existence of a feasible controller in the set, we prove that if the performance functions used at each time by the hysteresis algorithm are selected to be uniformly positive definite in the controller parameters, then one may safely set the hysteresis constant to zero without inducing chattering instability, and ensuring convergence to a performance-optimising controller. Expanding preliminary version of our work that we presented at the 2011 American Control Conference, the present paper adds new numerical simulation examples to demonstrate the application and benefit of the theory.     

Stable adaptive fuzzy control of nonlinear systems preceded by unknown backlash-like hysteresis

This paper deals with adaptive control of nonlinear dynamic systems preceded by unknown backlash-like hysteresis nonlinearities, where the hysteresis is described by a dynamic equation. By utilizing this dynamic model and by combining a fuzzy universal function approximator with adaptive control techniques, a stable adaptive fuzzy control algorithm is developed without constructing a hysteresis inverse. The stability of the closed-loop system is shown using Lyapunov arguments. The effectiveness of the proposed method is demonstrated through simulations.     

非伪控制解决惯性稳定平台的非线性时变干扰

非伪控制是一种基于在线数据的驱动控制方式.本文通过进化策略实现候选控制器的多样性操作,结合滞后算法切换控制器,从而实现系统自适应的PID稳定控制.在惯性稳定平台中,由于非线性时变干扰的存在令被控对象不能提供精确的控制模型,今将非伪控制算法用于惯性稳定平台中,能使惯性稳定平台准确地稳定框架,其方位轴稳定误差小于3.4mrad,俯仰轴稳定误差小于4.36mrad.     

Robust adaptive control of a class of nonlinear systems including actuator hysteresis with Prandtl-Ishlinskii presentations

This paper deals with robust adaptive control of a class of nonlinear systems preceded by unknown hysteresis nonlinearities. By using a Prandtl-Ishlinskii model with play and stop operators, we attempt to fuse the model of hysteresis with the available control techniques without necessarily constructing a hysteresis inverse. A robust adaptive control scheme is therefore proposed. The global stability of the adaptive system and tracking a desired trajectory to a certain precision are achieved. Simulation results attained for a nonlinear system are presented to illustrate and further validate the effectiveness of the proposed approach.     

Adaptation‐Enhanced Model‐Based Control with Charge Feedback for Piezo‐Actuated Stage

This paper proposes a new control design to compensate for the residual control error from charge feedback control. A part of the applied voltage is consumed by the hysteresis effect because of the nature of the piezoelectric material; moreover, this effect is difficult to overcome because it is rate dependent. This work utilizes a piezoelectric electromechanical model to propose a precompensation algorithm for a piezoelectric actuator. A nonlinear compensator can be used to treat both the hysteresis nonlinearity and the rate dependency of the system, and the adjustable parameters are specified through adaptive identification with only basic system information. The proposed design can position a piezoelectric stage with a magnifying mechanism within a few nanometers of a target, and the leftover hysteresis phenomenon is negligible.     

基于MGPI模型的SMA柔性驱动自适应NN控制

形状记忆合金(SMA)作为一类仿人肌肉驱动的智能柔性驱动材料,在机器人及高端制造等领域逐步得到应用,但由于SMA的热力学效应,造成输入输出之间存在强饱和回滞非线性,从而影响了驱动性能.此外在引入负载后, SMA柔性驱动部件输出性能表现出更为复杂的驱动特性.因此,如何有效抑制带载条件下SMA柔性驱动部件强饱和非线性影响,成为提升驱动性能的关键.针对此问题,本文重点研究带载条件下SMA柔性驱动部件的建模及驱动控制算法.针对SMA驱动部件中的强饱和非线性特性,本文提出一类修正(MGPI)回滞模型来进行表征.通过设定线性输入形状函数,不仅有效解析表征SMA驱动部件中的饱和回滞非线性,并且便于控制器设计.基于MGPI模型,考虑柔性驱动部件的动态特性,本文提出了带载条件下的SMA柔性驱动部件的自适应神经网络控制算法,实现考虑内部非线性和外部干扰条件下的驱动精度有效提升,并保证全局稳定性.     

Adaptive Pseudo Inverse Control for a Class of Nonlinear Asymmetric and Saturated Nonlinear Hysteretic Systems

This paper aims at eliminating the asymmetric and saturated hysteresis nonlinearities by designing hysteresis pseudo inverse compensator and robust adaptive dynamic surface control (DSC) scheme. The “pseudo inverse” means that an on-line calculation mechanism of approximate control signal is developed by applying a searching method to the designed temporary control signal where the true control signal is included. The main contributions are summarized as: 1) to our best knowledge, it is the first time to compensate the asymmetric and saturated hysteresis by using hysteresis pseudo inverse compensator because the construction of the true saturated-type hysteresis inverse model is very difficult; 2) by designing the saturated-type hysteresis pseudo inverse compensator, the construction of true explicit hysteresis inverse and the identifications of its corresponding unknown parameters are not required when dealing with the saturated-type hysteresis; 3) by combining DSC technique with the tracking error transformed function, the “explosion of complexity” problem in backstepping method is overcome and the prespecified tracking performance is achieved. Analysis of stability and experimental results on the hardware-in-loop platform illustrate the effectiveness of the proposed adaptive pseudo inverse control scheme.      

基于Prandtl-Ishlinskii模型的一类回滞非线性系统自适应控制

对带回滞驱动的一类单输入单输出的非线性不确定系统,本文采用Prandtl-Ishlinskii模型描述回滞特性,采用反步递推设计方法,实现自适应控制器的设计.仿真结果说明控制方法的有效性.     

ROBUST ADAPTIVE CONTROL OF PIEZOELECTRIC ACTUATORS WITH AN APPLICATION TO INTRACYTOPLASMIC SPERM INJECTION

This paper describes a robust adaptive control method for positioning piezoelectric actuators (ultrasonic motor) to achieve highly precise motion. The model employed to describe the motor is a second‐order linear model plus a nonlinear part comprising predominantly of a dynamical hysteresis. Based on the model, the overall control algorithm uses a PID component and an adaptive robust component for estimating the parameters of the piezo motor model. The adaptive component is continuously refined based on just prevailing input and output signals. Real‐time experimental results are provided to verify the effectiveness of the proposed scheme when applied to high precision motion trajectory tracking such as Intracytoplasmic Sperm Injection (ICSI).     

史密斯模糊整定PID控制器的设计及仿真

对传统的史密斯预估器进行改良.针对传统的史密斯控制系统过分依赖被控对象的精确数学模型、以及当预估器与实际对象有差异时控制效果不佳的缺点,提出了史密斯纯滞后补偿和模糊整定PID参数原理相结合的集成控制算法,该算法将该模糊自适应整定PID控制器引入史密斯控制系统中,用模糊控制器取代原系统的控制器;并将该方法用于激光晶体生长系统的直径调节器中,结果表明,该系统同时兼顾了史密斯控制和模糊控制的优点,对纯滞后、参数时变的激光晶体生长系统有很好的控制作用.