具有理想跟踪特性的鲁棒变结构模型参考自适应控制1)

针对相对阶为1的定常线性被控对象,提出了一种控制增益可切换的鲁棒变结构模型参考自适应控制方案.该方案在对象参数及高频增益符号均未知的情形下,可确保跟踪误差满足预先给定的过渡过程性能指标,即超调量、过渡过程时间和稳态误差.     

可具有非严格正实参考模型的变结构鲁棒自适应控制

提出了一种可具有非严格正参考模型的变结构鲁棒自适应的控制方案,可去除变结构模型参考自适应控制中普遍要求参考模型为严格正害或相当对阶大于１时参考模型补偿后严格正实的假设,在此基础上提出的变结构控制律可保保证跟踪误差在相对阶为１时于有限时间内收敛到零,而当相对阶大于１时则可使跟踪误差收敛到一个残差集内。     

具有理想跟踪特性的鲁棒变结构模型参考自适应控制

针对相对阶为1的定常线性被控对象,提出了一种控制增益可切换的鲁棒变结构模型参考自适应控制方案.该方案在对象参数及高频增益符号均未知的情形下,可确保跟踪误差满足预先给定的过渡过程性能指标,即超调量、过渡过程时间和稳态误差.     

降低鲁棒变结构模型参考自适应稳态控制增益的模糊实时分层方法

提出一种模糊实时分层方法来降低鲁棒变结构模型参考自适应稳态控制增益。利用模糊理论将一些定性经验与已提出的鲁棒变结构模型参考自适应控制相结合,可以在一定程度上克服稳态控制增益高的缺点。仿真结果表明,采用模糊实时分层方法后,稳态控制增益有所降低。     

Analysis and design of I/O based variable structure adaptivecontrol

This paper presents an overview of a technique for the design of variable structure model reference adaptive control (VS-MRAC) systems, using only input-output data. The main ideas underlying the design and the analysis, as well as the main properties of the controller, are described having as point of departure a well known parameter adaptive MRAC scheme. Then, asymptotic properties of the VS-MRAC system are established taking into account the effect of the averaging filters necessary to implement some equivalent control signals. In particular, global exponential stability of the associated error system with respect to a small residual set is demonstrated. The effect of linear zones in the relay functions is assessed showing that they can alleviate the chattering phenomena. This is related with the fact that the VS-MRAC has a high-gain stability property. A procedure for noise sensitivity reduction is also proposed. Simulations illustrate the very satisfactory performance of the VS-MRAC in adverse operating conditions     

A variable structure model reference robust control without a prior knowledge of high frequency gain sign

The design of a variable structure model reference robust control without a prior knowledge of high frequency gain sign is presented. Based on an appropriate monitoring function, a switching scheme for some control signals is proposed. It is shown that after a finite number of switching, the tracking error converges to zero at least exponentially for plants with relative degree one or converges exponentially to a small residual set for plants with higher relative degree, and the input disturbance can be completely rejected without affecting the tracking performance.     

高频增益符号未知时的变结构模型参考自适应控制

解决了对象相对阶大于1、高频增益符号未知时的变结构模型参考自适应控制(VS-MRAC)问题．提出了一种基于监控函数的控制信号切换律, 证明只需要对首个辅助误差构造监控函数, 就可决定控制信号的切换时间;进而, 在监控函数的管理下, 控制信号经至多有限次切换后将停止切换, 闭环系统所有信号一致有界, 跟踪误差将收敛到一个残集内, 且该残集可通过减小某些设计参数而变得任意小．特别地, 我们证明, 若系统的某些初始条件为零, 则至多只需要一次切换．     

AGV路径模糊─变结构滑模─模型参考协调控制

针对自动导向车（ＡＧＶ）的路径跟踪，提出一种新的模型参考－模糊变结构滑模－ＰＩ组合跟踪控制方案。该方案将ＡＧＶ设计成左右轮行走距离跟踪系统，并引进参考模型，组合了模糊控制和变结构滑模控制以及比例加积分（ＰＩ）控制。模糊变结构滑模控制提供了跟踪的快速性和稳定性，ＰＩ控制则消除稳态抖动，提高了稳态精度。仿真及实测结果表明，这种新的设计方案能达到较高的跟踪精度。     

高频增益符号未知时的变结构模型参考自适应控制:任意相对阶的控制律设计

讨论被控对象相对阶大于1且高频增益符号未知时的变结构模型参考自适应控制问题,从而将相对阶为1时的结果推广到任意相对阶.首先对关键信号构造监控函数,并在此基础上提出了一种控制信号切换律.进而证明,当被控对象相对阶大于1、高频增益符号未知时,在监控函数的监测下,相关控制信号经至多有限次切换后将停止切换,跟踪误差将收敛到一个残集内,且该残集可通过减小某些设计参数而变得任意小.特别,本文证明,与相对阶为1时相同,当对象相对阶大于1时,若系统的某些初始条件为零,则至多只需要一次切换.     

Automatic Voltage Regulator Design by Modified Discrete Integral Variable Structure Model Following Control

In power systems, the automatic voltage regulator (AVR) is designed to make the terminal voltage to accurately track the deviation of the reference voltage. To achieve the desired requirements, this paper proposes the modified discrete integral variable structure model following control (MDIVSMFC) approach. The MDIVSMFC approach comprises a reference model part for specifying the design requirements and a MDIVSC part for minimizing the errors between the plant and model. The non-ideal sliding motion is introduced to take the place of the ideal sliding motion in discrete-time systems. Its existence conditions are used to adapt the proposed approach to the discrete systems. The application of MDIVSMFC to an AVR design is developed. Procedures for determining the control function, the coefficients of the sliding surface and the integral control gain are also proposed in detail. Simulation results are compared with the IEEE type-I voltage regulator to demonstrate that the proposed scheme can achieve fast and robust responses.     

New results on output-feedback variable structure model-referenceadaptive control: design and stability analysis

The variable structure model-reference adaptive control(VS-MRAC) redesign and stability analysis, presented previously by the authors (1993) for the case of plants with relative degree n*⩽2, is generalized to the case of arbitrary n*⩾1. This paper presents a complete stability analysis in the general case. The redesign is based on the explicit consideration of input disturbances which may include the disturbance originated by the uncertainty of the plant high-frequency gain. This leads to a considerably simpler and less restrictive stability analysis as well as to a systematic controller design for external disturbance rejection. The overall error system is globally exponentially stable with respect to a small residual set. Robustness to unmodeled dynamics is also discussed     

A robust VS-MRAC using switching scheme for the gain of control variables

A switching scheme for the gain of control variable of a VS-MRAC system was recently presented for plants with relative degree one. In this paper, the scheme is extended to the general case of plants with arbitrary relative degree. By the establishment of the relationship between the tracking error and those auxiliary errors for the case of plants with relative degree greater than one, it is shown that as long as the performance indexes are guaranteed for the auxiliary errors, each of which is in dynamics a subsystem with relative degree one, the tracking error will converge to a small residual set in a prespecified transient time. Furthermore, the influence of averaging filters on the system is analysed and shows that it can be considered as, in a sense, unmodelled dynamics.     

鲁棒变结构模型参考自适应控制器的分析与设计(Ⅰ)

对含有未建动态ＳＩＳＯ定常线性系统提出了一种控制增益可切换的变结构模型参考自适应控制方案。其主要结果是：解决了当对象建模部分相对阶为１、高频增益符号未知时,确保跟踪误差满足预先给定的过渡过程性能指标（超调量,过渡时间和稳态误差）的问题。     

含结构不确定系统的变结构鲁棒自适应控制

讨论了含结构不确定SISO系统的变结构模型参考鲁棒自适应控制问题,提出了一种新的变结构控制方法,使得:1)系统在同时含参数及结构不确定性时,跟踪误差仍能在有限时间内收敛到零;2)无须假设参考模型为SPR(严格正实)函数.理论分析与数值仿真结果是一致的.     

Two‐Stage Tracking Control Via Output Feedback

An algorithm is proposed combining a high‐gain control and an internal‐model control for asymptotic output tracking in the presence of non‐decaying external disturbances. The plant output is the only signal used in the feedback loops. The algorithm is divided into two stages: high‐gain control is activated in the transient phase, forcing the output to quickly approach the reference trajectory, and is then taken over by an internal‐model controller in the steady phase so that perfect output tracking can be achieved with moderate gains and smooth control efforts. Smooth transition between the two control laws is ensured through an internal‐model observer, which serves as a relaying mechanism between the high‐gain control and the internal‐model control.     

Peaking free variable structure control of uncertain linear systems based on a high-gain observer

An output-feedback model-reference variable structure controller based on a high-gain observer (HGO) is proposed and analyzed. For single-input-single-output (SISO) linear plants with relative degree greater than one, the control law is generated using the HGO signals only to drive the sign function of the variable structure control component while the sign function gain, also called modulation, as well as the other components of the control signal are generated using signals from state variable filters which do not require high gain and are free of peaking. This scheme achieves global exponential stability with respect to a small residual set and does not generate peaking in the control signal.     

Development Of Cvt Control System And Its Use For Fuel‐Efficient Operation Of Engine

Continuously variable transmission (CVT) provides an automobile with the ability to change the gear ratio continuously, which can then improve not only ride quality such as acceleration performance but also fuel‐efficiency. However, to take advantage of the ability, a control system that can precisely control the gear ratio is required. This paper proposes such a control system for a belt‐driven CVT system. For controller design, first the CVT system is modeled by analytical and experimental approaches. The resultant static and dynamic characteristics provide a nonlinear first‐order model with an uncertain time constant and time delay. The nonlinear steady‐state gain is adjusted to one by a gain‐scheduled pre‐compensator. Thereby the plant model becomes a linear first‐order lag system with a dead time. The next step is controller design using the plant model. To guarantee stability and control performance against the parameter variation and time delay, the μ‐synthesis, a robust control method, is employed for feedback control. In addition, a feedforward controller is incorporated into the feedback control system to obtain better output response. The feedforward controller is given by a combination of the inverse system of the plant and a reference model that gives desired output response. As a result, the control system becomes a two‐degree‐of‐freedom control system. To evaluate the performance of the control system and its effectiveness on the fuel‐efficiency, computer simulation and driving tests were conducted. The simulation and experiment results prove that the proposed control system can make the gear ratio track a reference output quickly and precisely in the presence of the uncertainties. The results also show that the control system improves fuel‐efficiency by changing the gear ratio so that the engine torque and its revolution speed can satisfy optimum‐efficiency operating condition.     

On the convergence of a model reference adaptive control algorithm with unknown high frequency gain

A model reference adaptive control algorithm is shown not to be exponentially convergent when the high frequency gain of the plant is unknown. The implication is that such an algorithm will be lacking in some way in robustness.     

基于小波逼近的非线性系统鲁棒迭代学习控制

针对存在扰动的未知非线性系统,利用小波逼近将系统参数化,结合变结构控制技术,提出了一种鲁棒迭代学习控制算法.该算法采用迭代学习的方式修正小波逼近的系数,利用具有死区的滑模变结构技术保证算法的鲁棒收敛性.收敛性分析表明,每次迭代学习都将减小所得到的逼近系数与最佳系数的差异.因此,期望轨迹变化后,该算法针对以前轨迹的学习结果仍然可以起作用,部分克服了传统迭代学习控制的学习结果仅对某一特定轨迹有效的缺点.     

Direct tip regulation of a single-link flexible manipulator by adaptive variable structure control

Direct tip position regulation of flexible manipulators is one of the most challenging control tasks. There are mainly three problems to be addressed in order to achieve good performance. The first two control problems arise owing to the unstable zeros and complex poles in the system nominal part which is dominated by a transfer function. The third problem is the existence of unstructured uncertainties owing to the truncation of high-order resonance modes and system nonlinearities. Because of the above difficulties and in particular the non-minimum-phase nature, tip regulation task of flexible manipulators is usually solved indirectly: direct control of joint angle and suppression of the flexible link vibration. The aim of this study is to investigate the direct approach for tip regulation. Since the tip transfer function contains unstable zeros and the first few dominant flexible modes (complex poles), a reference model of the same order is selected which does not have any finite zero but all negative real poles. In order to force the system to follow the reference model in the presence of the unstructured uncertainties, a variable structure controller is adopted in which the switching surface is derived from the reference model. When in sliding mode, the system performs as the reference model. Hence there will be no vibration and the tip position regulation can be achieved when the system approaches steady state. To improve the system responses further, an adaptation law with dead-zone scheme is combined with the variable structure controller. Simulation results show that link vibrations have been eliminated and the control profile is fairly smooth.