基于输入整形的时滞系统最小拍控制

基于Ｎｙｑｕｉｓｔ准则,按照给定的相位稳定裕度设计ＰＩ控制器使一阶时滞对象稳定,然后引入输入整形控制器对输入进行整形,实现了一阶时滞对象的最小拍控制。在确定采用周期后,整个控制系统的设计尺需按相位稳定裕度的需求解析算出ＰＩ控制器的比例增益即可,设计简单,性能良好。仿真结果表明,该方法相当有效,实现的最小拍控制无纹波。     

直流调速系统中常规PI 与模糊PI 控制器的比较

转速电流双闭环直流调速系统中的PI控制器直接影响其调速性能,利用MATLAB分别建立了由常规PI与模糊PI控制器组成的转速电流双闭环控制直流调速系统的仿真模型,并进行了仿真。仿真结果表明,模糊PI控制器与常规PI控制器相比具有更好的动态稳定性和跟踪性能,对外界干扰具有较强的鲁棒性。     

PI参数混合整定法在闭环矢量控制系统中的应用

为使闭环矢量控制系统工作在最佳状态,提出了基于模型的离线式整定与模糊PI在线整定相结合的混合整定法.该方法首先根据矢量控制原理推导出系统的数学模型,采用恒转矩启动并自由停机的方法计算出转动惯量.然后根据数学模型计算PI参数和内环补偿量,构建了模糊PI控制器,提出了新的PI控制规则表.最后的对比实验表明,PI参数混合整定法提高了系统的动态性能和稳态精度,优于仅采用单一整定法的系统,验证了方法的有效性.     

基于模糊控制的双闭环直流可逆调速系统的设计

对于双闭环直流可逆调速系统,提出了一种将模糊控制与常规PI控制相结合应用在转速环调节器设计的方法。根据工程经验与专家知识所确定的模糊控制规则,进行模糊推理,实现转速环调节器参数的动态整定。应用Matlab软件构建了双闭环直流可逆调速系统的仿真模型,并对转速环分别采用模糊PI控制器和常规PI控制器的直流可逆调速系统分别进行仿真实验并对比结果。从仿真结果可以得出采用模糊控制可以对直流可逆调速系统的动态与静态特性、抗扰性能、恢复性能以及跟踪性能有比较明显的改善与提高。     

未建模动态增量补偿驱动的非线性PID控制及应用

针对一类具有强非线性、机理不清且动态特性随不同运行条件而变化的复杂过程, 将基于数据的建模技术与基于模型的控制策略相结合, 提出了未建模动态及其未知增量补偿驱动的非线性PID控制方法. 所提的算法将一步超前最优控制策略应用于PID控制器的参数设计, 并结合非线性补偿技术进行综合设计, 从理论上给出了PID控制器参数以及非线性补偿器设计的一般原则和方法, 为解决传统PID控制器参数难于整定的问题提供了方法和途径. 在此基础上, 分析了闭环系统的稳定性和收敛性. 最后, 将所提的控制算法进行数值仿真实验以及Pendubot系统平衡控制的对比实验, 实验结果表明, 在Pendubot的精确摩擦力模型未知的情况下, 所提算法能有效地消除系统未知时变不确定性的影响, 并尽可能地减少Pendubot摆角的波动, 将摆角控制在规定的目标值范围内.     

Optimal realizations of fixed-point implemented digital controllers with the smallest dynamic range

A novel approach is proposed to design optimal finite word length (FWL) realizations of digital controllers implemented in fixed-point arithmetic. A minimax-based search procedure is first formulated to obtain an optimal controller realization that optimizes an FWL closed-loop stability measure. Since this FWL closed-loop stability measure is solely linked to the fractional part or precision of fixed-point format, the resulting realization may not have the smallest dynamic range. A measure is then derived to indicate the dynamic range of fixed-point implemented realization. By choosing an appropriate orthogonal transformation of this dynamic range measure of the optimal precision controller realization, a numerical optimization method is developed to make the controller realization having the smallest dynamic range without sacrificing FWL closed-loop stability robustness. The proposed approach is more efficient than a direct optimization of some combined FWL closed-loop stability and dynamic range measure via a numerical means. The proposed approach is established within a unified framework that includes both the shift and delta operator parameterizations, which makes it possible to compare the closed-loop stability characteristics of the optimal FWL controller realizations using shift and delta operators, respectively. Through analysing the simulation results of a design example, some useful insights and understandings are obtained regarding the FWL controller realizations based on shift and delta operators.     

Design of decentralized PI control systems based on Nyquist stability analysis

This paper presents a simple, but effective, design method for decentralized PI control systems with guaranteed closed-loop stability. Nyquist stability conditions are used to derive the stability region for each PI controller in terms of the controller parameters. A detuning factor for each loop is specified based on a diagonal dominance index. Then appropriate controller settings are determined using this index and the stability region. Simulation results for a variety of 2 × 2, 3 × 3, and 4 × 4 systems demonstrate that the proposed design method guarantees closed-loop stability and provides good set-point and load responses.     

Velocity field control of a class of electrically-driven manipulators

This article addresses the control of robotic manipulators under the assumption that the desired motion in the operational space is encoded through a velocity field. In other words, a vectorial function assigns a velocity vector to each point in the robot workspace. Thus, the control objective is to design a control input such that the actual operational space velocity of the robot end-effector asymptotically tracks the desired velocity from the velocity field. This control formulation is known in the literature as velocity field control. A new velocity field controller together with a rigorous stability analysis is introduced in this article. The controller is developed for a class of electrically-driven manipulators. In this class of manipulators, the passivity property from the servo-amplifier voltage input to the joint velocity is not satisfied. However, global exponential stability of the state space origin of the closed-loop system is proven. Furthermore, the closed-loop system is proven to be and output strictly passive map from an auxiliary input to a filtered error signal. To confirm the theoretical conclusions, a detailed experimental study in a two degrees-of-freedom direct-drive manipulator is provided. Particularly, experiments consist of comparing the performance of a simple PI controller and a high-gain PI controller with respect to the new control scheme.     

基于PID和LQR的四旋翼无人机控制系统研究

为提高四旋翼无人机的飞行稳定性、无人飞行器控制系统的鲁棒性和控制精度,以建立的四旋翼无人机飞行控制系统模型为基础,采用现代控制理论与传统控制论相结合的方法,针对姿态角速率、姿态角分别设计内环LQR(线性二次型调节器)控制器,及外环PID控制的双回路闲环控制器.充分利用PID控制器易于掌握且对模型要求精度低、LQR控制器能改善内回路的动态特性和稳态性能的特点,完成四旋翼无人机的飞行控制.通过实验遴选该双闭环控制器相关参数并进行优化,实验结果表明所设计的双回路控制器控制性能指标良好.     

基于Matlab/xPC的直流电机参数辨识及双闭环控制研究

针对直流电机精确数学模型的获取及其双闭环控制器参数的整定问题,在Matlab/xPC目标环境使用递推最小二乘法对某型直流电机进行参数的在线辨识,获得某工作转速下的动态结构图参数.针对该结构图,在Simulink环境下对速度调节器和电流调节器的PI参数进行整定并仿真,达到满意效果后,将控制器下载到xPC目标机中,采用毫秒...     

On the use of bifurcation analysis for robust controller tuning for nonlinear systems

This paper presents a new approach to robust controller tuning for nonlinear systems. The main idea is to apply numerical bifurcation analysis to the closed-loop process, using the controller tuning parameters, the set points, and parameters describing model uncertainty (parametric as well as unmodeled dynamics) as bifurcation parameters. By analyzing the Hopf bifurcation and saddle-node bifurcation loci, bounds on the controller parameters are identified. These bounds depend upon the type as well as the degree of mismatch that exists between the plant and the model used for controller design.The method is illustrated by tuning a state feedback linearizing controller for an unstable reactor as well as by comparing a proportional-integral (PI) controller and a state feedback linearizing controller applied to a continuously operated fermenter. The feedback linearizing controller can result in better performance than the PI controller if a very accurate model of the process is known and if the operating conditions vary over a significant range. However, stability properties of systems controlled by feedback linearizing controllers can degrade significantly as the mismatch between the plant and the model increases. This is illustrated in the fermenter example by showing that bounds on the tuning parameter of the feedback linearizing controller are significantly tighter than the ones for the PI controller.     

深空环境下三星库仑编队重构控制研究

本文研究了深空环境下三星库仑编队构型重构控制问题.首先考虑外界环境干扰作用(主要以太阳光压为主)和德拜效应影响,推导出精确的三星库仑编队动力学方程.针对库仑编队动力学特性和太阳光压对于编队任务控制精度的影响,设计基于BP神经网络的PID控制方法.PID控制结构简单,稳定性好,BP神经网络具有超强的自主学习和非线性逼近干扰能力,二者有机结合,通过BP神经网络输出最优的PID控制参数组合,改变卫星所带电荷从而改变卫星之间库仑力大小,使编队渐近稳定并按期望距离和构型飞行.仿真结果表明基于BP神经网络PID控制性能明显优于传统PID控制,大大提高了编队控制精度和系统对于外界干扰的鲁棒性.     

A new class of nonlinear PID controllers with robotic applications

This paper introduces a new class of simple nonlinear PID controllers and provides a formal treatment of their stability analysis. These controllers are comprised of a sector-bounded nonlinear gain in cascade with a linear fixed-gain P, PD, PI, or PID controller. Three simple nonlinear gains are proposed: the sigmoidal function, the hyperbolic function, and the piecewise–linear function. The systems to be controlled are assumed to be modeled or approximated by second-order transfer functions, which can represent many robotic applications. The stability of the closed-loop systems incorporating nonlinear P, PD, PI, and PID controllers are investigated using the Popov stability criterion. It is shown that for P and PD controllers, the nonlinear gain is unbounded for closed-loop stability. For PI and PID controllers, simple expressions are derived that relate the controller gains and system parameters to the maximum allowable nonlinear gain for stability. A numerical example is given for illustration. The stability of partially-nonlinear PID controllers is also discussed. Finally, the nonlinear PI controller is implemented as a force controller on a robotic arm and experimental results are presented. These results demonstrate the superior performance of the nonlinear PI controller relative to a fixed-gain PI controller. © 1998 John Wiley & Sons, Inc. 15: 161–181, 1998     

含未知信息的轮式移动机器人编队确定学习控制

本文研究含未知信息的轮式移动机器人(wheeled mobile robots,WMR)的编队控制问题.首先,基于领航–跟随法和虚拟结构法,将WMR编队控制问题转化为跟随机器人对参考虚拟机器人的跟踪控制问题.然后,利用径向基函数神经网络(radial basis function neural networks,RBF NN)对WMR的未知系统动态进行学习,以及根据李雅普诺夫稳定性理论设计了稳定的自适应RBF NN控制器和RBF NN权值估计的学习率.依据确定学习理论,闭环系统内部信号在对回归轨迹实现跟踪控制的过程中满足部分持续激励(persistent excitation,PE)条件.随着PE条件的满足,RBF NN权值估计收敛到其理想权值,实现了对未知闭环系统动态的准确学习.最后,利用学习结果设计了RBF NN学习控制器,保证了控制系统的稳定与收敛,实现了闭环稳定性和改进了控制性能,并通过仿真验证了所提控制方法的正确性和有效性.     

永磁交流伺服系统的神经网络监督控制

针对经典比例积分微分(Proportional Integral Derivative,PID)算法需要准确的数学模型,抗参数摄动和外界干扰能力差,在高度跟踪过程中控制精度低的缺点,设计了基于径向基函数(Radial Basis Function,RBF)神经网络和传统PID复合的控制器,应用于交流伺服位置系统。利用PID控制器实现系统的闭环动力学性能,利用RBF控制器来提高系统的动、静态控制品质,完成了火箭炮位置伺服系统三闭环模型的建立与神经网络离线训练样本的选择,通过仿真表明了此算法可以有效地提高系统的动静态特性。     

基于模糊和PI控制的MIG焊接电源设计

针对模拟控制和单片机控制的脉冲MIG(Metal Inert Gas)弧焊电源控制系统灵活性差、控制精度低和可靠性差等缺点,设计了基于模糊和PI控制的MIG焊接电源控制系统。为了提高焊接电流的控制精度,控制焊接电流的PI参数在一个周期的不同阶段应该是不同,所以该系统的焊接电流控制采用变参数PI控制方法。在不同焊接条件下的PI参数由专家系统确定。为了提高电弧弧长的稳定性,电弧电压控制采用模糊控制方法。模糊控制和变参数PI控制算法分别由数字信号控制器(DSC)和现场可编程门阵列(FPGA)实现。最后,介绍了系统的硬件电路设计和软件流程。利用焊接铝板对该系统进行了测试,测试结果表明,基于模糊和PI控制的MIG焊接电源控制系统动态响应快、可靠性高、弧长控制稳定。     

一阶时滞过程的数字PI快速镇定算法

研究一阶时滞过程的数字PI镇定问题。研究表明,当闭环系统临界稳定时,实轴以外具有最小辐角的极点是临界稳定极点。通过确定临界稳定极点的位置,得到数字PI控制系统的稳定性判据。根据该稳定性判据,可以快速地确定数字PI控制系统的参数稳定域。     

PI tracking control for nonlinear time-varying delay Markov jump systems

This paper considers robust stochastic stability and PI tracking control problem for Markov jump systems with both input delay and an unknown nonlinear function. Based on the traditional PI control strategy, a new controller design scheme is proposed for nonlinear time-delay Markov jump systems which can realize multiple control objectives including robust stochastic stability and tracking performance. By using the Lyapunov stability theory and LMI algorithms, a sufficient condition for the solution to robust stochastic stability and tracking control problem is obtained. Then, the desired controller with PI structure is designed, which ensures the resulting closed-loop system is robust stochastically stable and the system state has favorable tracking performance. Finally, a numerical example is provided to illustrate the effectiveness of the proposed results.     

基于预测控制的刨花板施胶比值系统研究

在刨花板生产线施胶过程中,刨花施胶精度对刨花板的物理性能和环保性能影响较大。为了提高刨花施胶效果,设计了基于KPFC-PI的比值控制系统,将比值器和PFC作为控制系统外环,用以提高胶液流量按照比值工艺跟踪刨花流量的速度和鲁棒性,系统内环路采用PI控制器,增强系统抗干扰性,并通过调节PI参数,拟合简化整个内环路,作为外环PFC的一阶加纯滞后广义处理对象,用来减少干扰引起的偏差。通过仿真实验,说明了该控制器与PID控制相比,可有效提高刨花板施胶精度、保持施胶量稳定性和具有较强抗干扰性能。     

基于时延动态补偿的网络控制器的设计

在网络控制系统中由于网络带宽的限制,不可避免地使网络系统产生网络诱导时延,从而导致系统性能下降甚至不稳定。文章针对延时不确定使得Smith预估补偿控制效果差的问题,提出了新的Smith补偿控制算法,根据控制器反馈信息对网络延时进行动态补偿,并与模糊PI控制方法相结合,构成Smith预估模糊PI控制器,使得闭环控制系统即使在模型失配的情况下,仍具有较高的稳定性、较强的鲁棒性。仿真结果表明,该方法可行有效。