A design approach to adaptive model-following control of robotic manipulators

In this paper, the robot dynamics are represented by a nonlinear state-space model containing a disturbance term due to gravitational loading. Using a suitable linear time-invariant reference model, an adaptive model-following control problem is formulated which satisfies the matching conditions. The control input is designed to have two components: a nonadaptive linear component to do the task of model-following and a nonlinear unit-vector component based on hyperstability theory to do the adaptive task. An additional integral feedback term is further superimposed and then the overall asymptotic hyperstability is established. The simulation results on the first three joints of PUMA 560 robot manipulator indicate the potential of our design approach.Based on research supported by Kuwait University Research Administration under Grant No. EE 049.     

Nonlinear adaptive model-following control

The use of discontinuous control in adaptive model-following continuous control systems with nonlinear time-varying plant is described. The first approach is based on the theory of variable structure systems. Hyperstability theory is the basis of the second scheme; the third one results by combining the previous approaches. The link among the three approaches is explored by studying the error dynamics. Practical implementation and applications are discussed.     

Synthesis of adaptive gain robust model-following/tracking controllers for a class of uncertain linear systems

This paper proposes a new adaptive gain robust model-following/tracking controller for a class of uncertain linear systems. The proposed adaptive gain robust controller is composed of state feedback laws with fixed gains, feedfoward inputs for the reference model and nonlinear compensation inputs with adjustable time-varying parameters. Moreover, the proposed control strategy can achieve good transient performance and avoid the excessive control input by means of the design parameter. In this paper, linear matrix inequality-based sufficient conditions for the existence of the proposed adaptive gain controller are given, and two design strategies are presented. Finally, simple illustrative examples are included to show the effectiveness of the proposed adaptive gain robust controller.     

Integrated identification and robust control

A framework for integrated identification and control is presented. As part of this framework, frequency domain uncertainty bounds are derived for robust stability tests, a robust stability test for elliptical bounds is developed for SISO systems, a methodology for estimating controller performance is derived, and an optimal experiment design methodology for control-relevant identification is outlined. An example is presented to illustrate how the tools of the framework fit together.     

Robust model-following controller design for LTI systems affected by parametric uncertainties: a design example for aircraft motion

This article addresses the design problem of a robust model-following controller (MFC) which minimises the error between plant controlled output and model output for a linear time-invariant (LTI) plant system affected by parametric uncertainties and an LTI target model. To design such an MFC, a previously proposed MFC scheme, whose applicability has already been demonstrated with flight controller design, is adopted in this article. Our design procedure is as follows: first, a basic MFC is designed using the nominal LTI plant model and the LTI target model while a structured free matrix in the MFC is not assigned; second, model-following performance of the MFC for appropriately defined disturbance input and model input for the parametric uncertain plant model and the LTI target model is minimised using the structured free matrix; and finally, a robust MFC is obtained using the basic MFC and the optimal structured matrix. In the second step, an iterative design method for robust H ₂ controllers for LTI parameter-dependent (LTIPD) systems using parameter-dependent Lyapunov functions (PDLFs), which is also proposed in this article, is applied. Two MFCs for the lateral-directional (L/D) motions of a research aircraft, which has been developed for an in-flight simulator, for two different real aircraft models, i.e. a Boeing 747 model and a Lockheed Jetstar model, are designed and their performance is confirmed via numerical simulations and flight tests.     

An alternative structure for next generation regulatory controllers: Part I: Basic theory for design, development and implementation

Even though employed widely in industrial practice, the popular PID controller has weaknesses that limit its achievable performance, and an intrinsic structure that makes tuning not only more complex than necessary, but also less transparent with respect to the key attributes of the overall controller performance, namely: robustness, set-point tracking, and disturbance rejection. In this paper, we propose an alternative control scheme that combines the simplicity of the PID controller with the versatility of model predictive control (MPC) while avoiding the tuning problems associated with both. The tuning parameters of the proposed control scheme are related directly to the controller performance attributes; they are normalized to lie between 0 and 1; and they arise naturally from the formulation in a manner that makes it possible to tune the controller directly for each performance attribute independently. The result is a controller that can be designed and implemented much more directly and transparently, and one that outperforms the classical PID controller both in set-point tracking and disturbance rejection while using precisely the same process reaction curve information required to tune PID controllers. The design, implementation and performance of the controller are demonstrated via simulation on a nonlinear polymerization process.     

论PID与自耦PID控制理论方法

PID增益鲁棒性差的突出问题引起了作者质疑PID控制理论的动机,提出了自耦PID协同控制理论方法,意外解决了PID增益鲁棒性差与抗扰动鲁棒性差的科学问题,形成了前期研究成果.然而,前期成果没有科学阐明自耦PID控制律及其整定规则的理论依据,没有科学揭示PID潜在的基础理论问题.为此,本文通过PID控制系统的物理属性分析,首次揭示了PID御用概念会引起量纲冲突与不协调控制机理两个矛盾,提出了解决这两个矛盾的科学设想.本文研究不仅阐明了纠错PID御用概念的必要性和迫切性,科学解释了自耦PID控制律及其整定规则的理论依据,而且开创了遵循量纲匹配原则的控制理论发展方向,具有重要科学意义.     

Robust attitude tracking control of small-scale unmanned helicopter

Robust attitude control problem for small-scale unmanned helicopters is investigated to improve attitude control performances of roll and pitch channels under both small and large amplitude manoeuvre flight conditions. The model of the roll or pitch angular dynamics is regarded as a nominal single-input single-output linear system with equivalent disturbances which contain nonlinear uncertainties, coupling-effects, parameter perturbations, and external disturbances. Based on the signal compensation method, a robust controller is designed with two parts: a proportional-derivative controller and a robust compensator. The designed controller is linear and time-invariant, so it can be easily realised. The robust properties of the closed-loop system are proven. According to the ADS-33E-PRF military rotorcraft standard, the controller can achieve top control performances. Experimental results demonstrate the effectiveness of the proposed control strategy.     

滑模变结构控制理论及其算法研究与进展

针对近年来滑模变结构控制的发展状况,将滑模变结构控制分为18个研究方向,即滑模控制的消除抖振问题、准滑动模态控制、基于趋近律的滑模控制、离散系统滑模控制、自适应滑模控制、非匹配不确定性系统滑模控制、时滞系统滑模控制、非线性系统滑模控制、Terminal滑模控制、全鲁棒滑模控制、滑模观测器、神经网络滑模控制、模糊滑模控制、动态滑模控制、积分滑模控制和随机系统的滑模控制等.对每个方向的研究状况进行了分析和说明.最后对滑模控制的未来发展作了几点展望.     

不确定非线性系统的神经网络智能重构控制

针对一类不确定非线性动态系统,提出了一种基于神经网络动态补偿的鲁棒模型跟随重构控制策略.该方法吸取了线性模型跟随方法的基本思想,通过引入神经网络在线补偿控制器,以克服系统由故障引起的未建模非线性动态的影响,从而提高模型跟随重构控制的动态性能和稳态精度;并且当系统存在模型不确定性时,其输出仍能精确地跟踪理想模型的输出.文中还给出了特定假设条件下闭环重构控制系统稳定性的严格证明.理论分析和仿真研究表明,所提的方法是有效的并可保证闭环系统具有良好的重构性能.     

双重控制策略在流媒体连续播放中的应用

传统的发送速率控制和播放速率控制由于各自的局限性,很难克服网络时延扰动对流媒体连续播放的影响.为了改善播放系统的性能,将双重控制策略应用到流媒体播放中,在发送端发送速率控制采用了内模控制器以克服传输延迟的影响,在接收端播放速率控制采用了简单的PID控制器,两种控制共同调节缓冲区长度.实验表明该方法能够处理传输时延和网络扰动引起的失步对播放的影响,缓冲区长度能够稳定在合理的区间,有效地防止缓冲区下溢造成的播放停顿以及缓冲区上溢造成的播放跳跃.发送速率变化率较小,有利于避免网络拥塞的发生.尤其是在网络出现大的扰动时,与其他方法相比,控制效果更加理想,播放更加流畅.     

一种新型PID控制的全数字锁相环的设计与实现

一种采用积分分离的PID控制作为环路滤波器的全数字锁相环。该滤波器对序列滤波器输出的加减脉冲个数在反馈信号的上升沿进行综合,然后通过PID控制算法将综合值作为压控振荡器的分频值来实现相位的调整,最终达到相位锁定。PID控制算法响应时间短并可控制超调量,相比PI算法具有更快的上升时间,且不增加超调量。另外,该环路具有结构简单、易于集成等特点,可以作为一个子系统或功能块构成片上系统(SoC),用以提高控制系统的可靠性,简化系统硬件结构。     

具有比例积分结构的广义预测自校正控制器

本文通过对一般预测控制中目标函数的改进，导出了具有比例积分结构的广义预测自校正控制器，从而极大地改善了控制器性能。仿真结果表明了该算法的有效性，对促进自校正控制器在工业中的应用具有一定意义。     

网络控制系统PI预测控制及稳定性分析

将PID反馈原理引入广义预测控制（GPC）思想,把GPC目标性能函数改造成具有PI的结构形式,根据反馈时延导出多步控制序列,通过时延补偿器对前向时延进行补偿,使控制性能在网络环境下得到极大改善。控制器结合了PID控制和预测控制的优点,具有较强的鲁棒性和工程意义。构造Lyapunov函数对闭环系统的稳定性进行分析,并通过仿真验证了该算法的有效性。     

组合航天器的姿态控制与结构鲁棒控制分配

针对空间臂捕获未知目标航天器后的控制问题, 本文提出了一种新方案. 基于动量的估计方法和递推最小二乘 算法在线估计组合式航天器的惯性参数, 并通过一种基于比例微分反馈的直接参数方法处理组合姿态控制系统, 此方法 给出了完整的参数化双反馈增益. 考虑到推力器的配置和配置矩阵的测量误差, 提出了具有多面体和多胞体形式摄动的 鲁棒控制分配方法. 最后, 数值仿真结果验证了所提方法的有效性.     

A Synthesis Method For Robust Pid Controllers For A Class Of Uncertain Systems

PID controller design is considered where optimal controller parameters are found with constraint on maximum sensitivity and robustness with regard to a cone bounded static nonlinearity acting in feedback with part of the plant. The design procedure has been successfully applied in the synthesis of a controller for an Anti‐lock Braking System (ABS).     

一种无人机大机动飞行控制方法

研究了无人机进行大机动的控制问题,提出了一种传统动态逆控制方法的改进方法.在外环的气流角控制器中,通过引入加速度反馈,避免了传统方法的气动力估算环节,从而提高了对气动数据不准确的鲁棒性.在内环的角速率控制器中,使用基于LPV(linear parameter-varying)系统鲁棒PI控制方法,从理论上保证了整个机动飞行过程中的鲁棒性.仿真结果表明,提出的方法能够实现无人机纵向和横航向同时进行机动的控制,同时具有较好的控制性能.     

A Frequency-Dependent Direct Adaptive Scheme for Robot Manipulators: A Case of Model-Following Motion Control

This paper presents a new frequency-dependent direct adaptive scheme for the optimal and/or suboptimal tracking of the motion of a prescribed model. The idea is based on a closed-loop control scheme in which an _{2 H} optimal/suboptimal controller is applied in parallel with a direct adaptive technique to guide a robot manipulator to follow a certain prescribed trajectory. The H ₂ compensators have to be proper and positively bounded with respect to all dynamic frequencies. Robustness issues are addresses in the paper by lumping all the nonlinear dynamic terms such as the centrifugal and Coriolis effects as well as the mechanical and electrical friction forces of the robot arm, into a general unstructured uncertainty term.     

鲁棒控制理论应用于宏观经济系统分析

针对宏观经济系统模型的不确定性，运用鲁棒控制理论进行宏观经济系统的分析与决策，使得宏观经济系统能够保持鲁棒稳定性并准确跟踪预先给定的目标。     

A hybrid PC/PLC architecture for manufacturing-system control—theory and implementation

This paper presents a novel and generic PC/PLC-based software/hardware architecture for the control of flexible manufacturing workcells. The proposed implementation methodology is based on the utilization of any one of the available formal discrete-event-system control theories in conjunction with state-of-the-art industrial programmable-logic controllers (PLCs). The methodology has been illustrated to be a viable technique through its actual implementation in our laboratory using a robotic-workcell testbed. The specific control theory used is a combination of Extended Moore Automata and Ramadge-Wonham Automata that has been developed by our research group. The modular control software architecture has been developed for MS-Windows environments (running on one PC interfaced to the PLCs) and allows the use of different formal control theories as well as different commercial PLC hardware. The effective graphical user interface provides a transparent programming environment, where users are not expected to have a full knowledge of the formal control theory used.