交流伺服系统的改进内模控制

针对交流伺服系统,基于改进内模控制提出二自由度控制方法。根据积分加一阶环节特点,采用合成法设计设定值跟踪控制器,根据内模控制原是设计抗扰动控制器,设定值跟踪控制器和扰动抑制控制器可通过单个性能参数独立调节和优化,避免了控制器调节的随机性和复杂性。保证系统具有较好的设定值跟踪性能和抗扰动性能的同时,很大程度提高了系统的鲁棒性。仿真研究和实验结果验证了控制方案的有效性。     

线控转向系统的前轮转角跟踪策略研究

研究通过对线控转向系统进行主动控制,可靠并准确地得到期望的前轮转角。基于建立的线控转向系统数学模型,使用非线性自回归模型确定其系统参数,设计内模控制器跟踪车辆的期望运动状态。通过开环和闭环试验,对控制器在典型的驾驶工况下的有效性进行了验证。通过与PID控制器的结果对比,证明所设计的内模控制器能提供更好的控制性能。为减少驾驶员的操纵负担并确保车辆在不同行驶条件下的稳定性,根据不同工况下的测试结果提出基于增益不变的变角传动比控制策略,并设计了滑模控制器跟踪期望横摆角以实现主动转向。通过对内模和滑模控制器的联合仿真结果表明,所设计的控制器可实现期望横摆角度的精确跟踪,显著提高车辆的操纵灵活性和稳定性。     

基于全状态观测器状态反馈的多轴转向极点配置

提出了一种利用观测器进行状态重构并利用重构状态进行反馈配置极点来改善多轴转向车辆性能的方法。建立了多轴转向车辆二自由度（2DOF）模型,基于系统输入和易测得的横摆角速度设计全状态观测器重构侧偏角,并根据系统希望极点和重构状态,设计状态反馈控制器进行极点配置。通过仿真验证,观测器能准确跟踪车辆状态,转向反应迅速而平稳,且在后轮转角±5°范围内具有鲁棒性,控制效果明显优于PID控制的控制效果。结果表明,控制器能有效改善多轴转向车辆动态品质,提高操纵稳定性。     

基于内膜原理的多轴转向无静差跟踪鲁棒控制

为提高多轴转向车辆跟踪控制精度及其抗干扰能力,提出基于内模原理(IMP)的无静差跟踪鲁棒控制方法。建立多轴转向二自由度线性模型,并基于IMP进行无静差跟踪控制器设计,利用极点配置方法求解控制器;对某三轴转向车辆进行跟踪控制器设计,并和PID控制对比仿真,在一定干扰下,内膜控制跟踪横摆角速度阶跃和斜坡信号的稳态误差均为零,调节时间在0.09 s以内,而PID控制稳态误差最大0.2°/s,调节时间最大为0.6 s。结果表明控制算法能使横摆角速度无静差跟踪参考输入,并具有一定的鲁棒性,且侧偏角响应也得到改善,跟踪效果明显优于PID控制,提高了多轴转向的操纵稳定性和安全性。     

二自由度PID在PMSM电流环中的应用

针对电流环频域数学模型,设计了一种二自由度控制器并给出了参数整定方法。基于期望的系统阻尼比和阶跃响应的上升时间,结合极点配置理论计算得到二自由度控制器参数。仿真和实验结果表明,相较于传统PI控制,采用二自由度控制的永磁同步电机(PMSM)调速系统有效地解决了常规PI控制难以兼顾电流环的跟踪性能与抗扰性能的缺陷。     

基于采样控制理论的光电跟踪伺服系统内模控制研究

针对外部扰动对光电跟踪伺服系统精度的影响,对稳定回路提出了一种两自由度内模控制,将控制器的设计转化为标准的H∞优化问题,使得系统对模型误差及参数摄动具有较强的鲁棒性。采用jump变换、提升操作等采样控制系统的理论与方法来优化设计相应的鲁棒控制器,综合考虑了系统的多采样率行为及采样点间的动态特性。仿真结果表明了所设计的控制系统具有较高的指令跟踪精度及较强的扰动抑制性能。本文的研究为高精度光电跟踪伺服控制系统的设计提供了新方法。     

基于SDRE方法的汽车线控转向系统控制方法研究

利用状态相关Riccati方程(SDRE)方法对汽车线控转向系统控制器进行研究。通过车辆动力学和轮胎模型,建立线控转向系统的状态相关系数结构(SDC)方程;针对动力学方程具有高度非线性的特点,设计了基于SDRE方法的控制器;最后采用θ-D方法对SDRE控制器进行求解,以提高计算效率并保证足够的控制精度。实验平台仿真结果表明:采用SDRE方法设计的线控转向系统控制器具有较高的跟踪精度,可提高车辆操纵稳定性并减少电机能量消耗等。     

气压伺服系统高性能鲁棒控制器的设计

2自由度控制器越来越在伺服控制中显示其优越性。2自由度控制利用反馈控制来保证稳定性,利用前馈保证轨迹跟踪性能。首先辨识得到了气压系统的闭环传递函数。基于闭环系统辨识模型设计了零相位误差前馈控制器(ZPETC),ZPETC将闭环系统带宽拓宽为100 rad/s左右。系统的干扰抑制能力、鲁棒稳定性由控制器中反馈环节保证。设计了基于干扰观测器的内环反馈控制;外环反馈仍为位置反馈环节。与PID控制比较,整个控制器在试验中得到了良好的轨迹跟踪精度。     

分布式驱动智能汽车轨迹跟踪的协同控制

针对车辆在轨迹跟踪过程中，尤其是高速转向等极限工况下，易出现车辆跟踪精度差和失稳的问题，以分布式驱动智能汽车为研究对象，提出一种考虑横向稳定性的轨迹跟踪协同控制策略。首先，建立车辆纵向、横向以及横摆运动的三自由度动力学模型，设计了基于模型预测控制的主动转向控制器，通过优化求解得到跟踪期望轨迹的最佳前轮转角。然后，采用滑模控制设计横摆力矩控制器，将横摆角速度和质心侧偏角作为联合变量，利用积分二自由度控制模型，计算车辆稳定的等效附加横摆力矩。最后，采用二次规划算法设计最优力矩分配控制器，以满足总的驱动力矩和附加横摆力矩的控制需求。仿真试验结果表明，控制系统在极限高速工况下，能够使车辆精确、稳定的跟踪期望轨迹。     

直线伺服系统时滞参数辨识与补偿研究

为解决直线伺服固有时滞特性对轨迹跟踪性能的影响,以典型的前馈加反馈二自由度控制结构为基础,分析直线伺服时滞特性对其轨迹跟踪精度的影响。在此基础上设计了前馈环节上的时滞控制器,之后针对时滞控制器位于前馈通道时作为一个超前环节控制上无法实现的问题,将时滞参数分为两部分,分别调节理想轨迹指令按照整数倍伺服周期延时及前馈控制信号滤波延时以达到时滞补偿的目的,引入牛顿迭代寻优进行最优时滞参数辨识。仿真与试验结果表明,在前馈加反馈二自由度控制的基础上加入时滞控制器可以有效减小直线伺服系统的闭环位置跟踪误差,特别是显著减小非零加加速度段的闭环位置跟踪误差,提高轨迹跟踪性能。     

Robust internal model control of servo motor based on sliding mode control approach

This paper proposes a robust internal model control (IMC) based on sliding mode control (SMC) approach for high-performance motion control of a servo motor subject to uncertainties and/or disturbances. The proposed control strategy considers not only the simplicity and intuition of the IMC-based controller for a prescribed tracking performance but also the effectiveness of the SMC scheme to guarantee the robustness of the servo system. Since the performance of the IMC-based controller can be analyzed via a SMC structure, a robust control law based on the SMC technique is introduced into the IMC scheme to decrease the sensitivity to uncertainties and enhance the resistance to disturbances. Moreover, the 2-degree-of-freedom IMC integrating the robust SMC scheme is developed to further improve the control performance. The stability is analyzed based on Lyapunov theory, and the theoretical results show that a prescribed transient tracking performance and a final tracking accuracy of the servo system can be guaranteed. Comparative simulations and experiments are investigated to verify the high performance nature of the proposed control strategy.     

Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics

In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance.     

基于改进H∞算法的线控转向系统仿真研究

针对汽车线控转向系统的鲁棒性问题,对汽车线控转向的原理和结构方面进行了研究;对汽车线控转向的动力学模型进行了建立以及简化;对汽车线控转向控制系统进行了分析与设计.以H∞运算为基础,利用反求法,避开了加权函数的选择,通过观察H∞运算中S/T奇异值曲线,运用符合线控转向鲁棒性能要求的预期S/T曲线逆转了该闭环系统,构建出了闭环传递函数,提出了一种基于改进H∞算法的线控转向系统.通过对线控转向系统的时间域和频率域的分析,以及线控转向系统模型干涉和参数扰动下的仿真结果分析,验证了改进H∞算法的控制策略的准确性.研究结果表明,基于改进H∞算法的线控转向系统在保证了鲁棒稳定性的前提下,具有更好的响应性能;并且改进的控制器比传统的控制器具有更好的鲁棒性.     

Vehicle active steering control research based on two-DOF robust internal model control

Because of vehicle’s external disturbances and model uncertainties, robust control algorithms have obtained popularity in vehicle stability control. The robust control usually gives up performance in order to guarantee the robustness of the control algorithm, therefore an improved robust internal model control(IMC) algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness. The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties. In order to separate the design process of model tracking from the robustness design process, the improved 2 degree of freedom(DOF) robust internal model controller structure is given from the standard Youla parameterization. Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm, on the basis of a nonlinear vehicle simulation model with a magic tyre model. Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance, which can enhance the vehicle stability and handling, regardless of variations of the vehicle model parameters and the external crosswind interferences. Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.     

直线电机精密定位平台轨迹跟踪控制器设计

为了实现直线电机精密定位平台的位置和速度的轨迹跟踪控制,本文基于内模控制（IMC）的基本原理,在直线电机精密定位平台参数辨识的基础上,设计了定位平台速度环的模型状态反馈（MSF）控制器和基于位置环PID和速度环MSF的级联控制器。将PID/MSF级联控制器与速度/加速度前馈控制（VFC/AFC）相结合,构成了PID/MSF+VFC/AFC的复合轨迹跟踪控制器。该复合轨迹跟踪控制器通过整定速度前馈的增益来改善位置环偏差控制的跟踪滞后现象和动态响应,增加控制系统的稳定性和伺服精度;通过整定加速度前馈的增益在不减小级联控制器位置环增益的前提下,减小速度前馈带来的超调量,提高轨迹跟踪精度。基于MATLAB/dSPACE实时仿真控制平台,实现了某直线电机平台的轨迹跟踪控制。仿真和实验结果表明,该轨迹跟踪控制器的轨迹跟踪精度为±0.028 mm,定位精度为±4 μm,满足直线电机精密定位平台轨迹跟踪控制的要求。     

Heating-up control with delay-free output prediction for industrial jacketed reactors based on step response identification

To improve the heating-up control performance for industrial jacketed reactors typically involved with long input delay, a predictor-based two-degree-of-freedom (2DOF) control scheme is proposed for the heating-up process operation, based on model identification from a practical step response test. By performing a simple step test (i.e., turning on the electrical heater with certain power (e.g., 50% or 100% of the heating power) to observe the heating-up temperature response), a transfer function identification method is developed to establish an integrating type process model with time delay for describing fundamental dynamics of the heating-up response. Based on the identified model, a predictor-based 2DOF control structure is established, where the delay-free output prediction is obtained by constructing two filters. The 2DOF controllers are analytically derived by proposing the desired transfer functions for the set-point tracking and load disturbance rejection, respectively. There is a single adjustable parameter in each controller (or filter), which may be monotonically tuned to obtain the desired control (or prediction) performance. Illustrative examples from the existing references and a practical application to a 4-liter jacketed reactor for pharmaceutical crystallization are given to demonstrate the effectiveness and advantage of the proposed identification and control methods in comparison with the existing methods.     

Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system

Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems.     

Discrete-time domain two-degree-of-freedom control design for integrating and unstable processes with time delay

A discrete-time domain two-degree-of-freedom (2DOF) design method is proposed for integrating and unstable processes with time delay. Based on a 2DOF control structure recently developed, a controller is analytically designed in terms of the H₂ optimal control performance specification for the set-point tracking, and another controller is derived by proposing the desired closed-loop transfer function for load disturbance rejection. Both controllers can be tuned relatively independent to realize control optimization. Analytical expression of the set-point response is given for quantitatively tuning the single adjustable parameter in the set-point tracking controller. At the meantime, sufficient and necessary conditions for holding robust stability of the closed-loop control system are established for tuning another adjustable parameter in the disturbance rejection controller, along with numerical tuning guidelines. Illustrative examples from the literature are used to demonstrate the effectiveness of the proposed method.