基于定量反馈理论的时滞系统自抗扰控制参数整定

工业过程对象普遍存在时滞、模型参数不确定性和外部扰动多等特点,传统Smith预估控制方法难以设计出满足期望性能的鲁棒控制器.针对模型参数不确定性和外部扰动,本文采用自抗扰控制技术进行估计和补偿.针对系统存在时滞的特点,本文提出改进Smith预估器结构,提升扩张状态观测器对于扰动估计的实时性.在此基础上,本文以一阶时滞系统为例提出了控制器参数整定方法.首先根据最优参数选取准则确定预估器模型,然后在等效模型框架下采用定量反馈理论整定自抗扰控制器参数,确保控制系统达到预期性能指标.在仿真实验中,将所提出方法与几种常见时滞系统控制方法进行比较,通过设定值跟踪、抗扰及蒙特卡罗实验验证了所提出方法具有良好抗扰能力与鲁棒性.     

Decoupling two-degree-of-freedom control strategy for cascade control systems

In this paper, two new two-degree-of-freedom control structures are proposed for cascade control systems, both of which are identical in the controller design procedure. The primary controller used for setpoint tracking is derived in terms of H₂ optimal performance objective. The secondary controller is responsible for rejecting load disturbances that seep into the intermediate process and therefore is called a load disturbance estimator, which is inversely figured out by proposing the desired complementary sensitivity function of the inner loop for disturbance rejection. As a result, the nominal setpoint response is decoupled with the load disturbance response of the inner loop, both of which can be optimized independently. Based on the control system stability analysis, the rule of thumb for tuning the single adjustable parameter of each controller is provided to cope with the process uncertainty in practice. Several illustrative examples are included to demonstrate the superiority of the proposed method.     

液压机器人的预测函数控制

针对液压机器人系统存在较大的不确定性及干扰 ,其特征参数将随工况的变化和外载及环境的影响产生大幅度变动的特点 ,提出一种预测函数控制 (PFC)和 PID相结合的新方法。该方法相当于一个 PFC- P控制结构 ,通过其本身内环来克服随机干扰 ,外环采用预测函数控制来获得优良的跟踪性能和鲁棒性 ,实现目标和控制的分层。仿真结果表明 ,该 PFC- P控制方法能兼顾跟踪性、鲁棒性和抗干扰性等性能指标 ,可获得满意的控制效果     

Simple control method for integrating processes with long deadtime

Control of integrating processes with long deadtime is a challenging problem. Using original Smith predictor control structure will result in an offset problem during load disturbance. Using the internal model control (IMC) principle to design the control structure will result in large overshoot during servo response. In this work, a simple modified Smith predictor controller design is proposed for this important type of system. The overall control structure has only two physically meaningful tuning parameters. One is used to set the speed of the closed-loop servo response and the other tuning parameter is used to set the speed of the closed-loop load response. Two examples are used to demonstrate the improved closed-loop performance of the proposed controller design.     

一种三自由度串级控制的仿真研究

关于优化控制系统性能问题,由于控制系统中存在非线性滞后各种干扰因素,严重影响响应和稳定性。为实现在线独立调节副回路设定响应与扰动抑制响应,增强主回路的抗干扰能力,改善系统性能,提出一种新的三自由度串级控制方法。在副回路中采用两自由度内模控制,主回路采用单位反馈控制结构,并根据闭环最优灵敏度函数方法确定主控制器,从而保证系统的整体性能。对各个控制器的解析建模设计,对每个控制器都可以进行单参数调节和优化,并对主回路和副回路存在的乘性不确定性进行仿真。仿真结果表明,新的控制方法具有较好的设定值跟踪性能和抗干扰能力,提高了系统的鲁棒稳定性。     

Analytical design of two-degree-of-freedom control scheme for open-loop unstable processes with time delay

This paper proposes an analytical two-degree-of-freedom control scheme for open-loop unstable processes with time delay, which leads to the remarkable improvement of regulatory capacity for both of reference input tracking and load disturbance rejection. Firstly a conventional proportional or plus derivative controller is deliberately employed for stabilizing the setpoint response. Then the setpoint tracking controller is analytically derived in terms of the integral-squared-error (ISE) performance specification. By proposing the desired closed-loop complementary sensitivity function for rejecting load disturbances, the corresponding controller, i.e. disturbance estimator, is inversely figured out. Hence the nominal setpoint response is decoupled from the load disturbance response by virtue of the open-loop control manner for the setpoint tracking. In consequence, both of them can be optimized simultaneously and separately. At the same time, robust stability analysis for the proposed control structure is provided in the presence of the process multiplicative uncertainty. Accordingly the on-line tuning rule for the single adjustable parameter of each controller is suggested to cope with the process unmodeled dynamics in practice. Finally, several illustrative examples are included to demonstrate the superiority of the proposed method.     

An automatic tuning methodology for a unified dead-time compensator

In this paper, an automatic tuning methodology for a modified Smith predictor control scheme is proposed. The main feature of the procedure is that it is applied in closed-loop (by either evaluating a set-point or a load disturbance step response) and it is suitable for self-regulating, integral and unstable processes. Further, the process parameter estimation technique is based on the evaluation of the integral of signals, thus making it inherently robust to measurement noise. Simulation and experimental results demonstrate the effectiveness of the methodology.     

容错逆变器驱动的PMSM双环预测控制的研究

为了提高三相四开关容错逆变器驱动的永磁同步电机调速系统的性能,提出了调速系统双闭环预测控制策略。在转速环中设计了带扰动补偿的模型预测控制方法,通过离散扰动观测器估计负载扰动并进行前馈补偿,与模型预测速度控制相结合得到[q]轴电流环的期望给定值。在电流环中设计了基于离散滑模的有限控制集模型预测控制方法。通过与传统PI、FCS-MPC方法进行仿真对比,验证了该方法在空载启动、给定转速突变以及存在负载扰动、参数变化时,可使容错逆变器驱动的永磁同步电机调速系统具有更好的动态响应能力和鲁棒性。     

基于高阶滑模速度控制器的异步电机模型预测转矩控制

针对三相异步电机驱动系统,提出一种基于高阶滑模速度控制器的模型预测转矩控制策略.为了降低负载扰动对系统运行性能的影响,设计一种基于二阶Super-Twisting滑模技术的速度环控制器,以代替传统PI速度控制器,并应用Lyapunov稳定性理论对其稳定性和鲁棒性进行分析,得到使速度控制系统收敛的参数范围.为了提升转矩控制精度,基于异步电机的数学模型,采用模型预测转矩控制理论,以转矩和定子磁链为控制目标设计评价函数,得到最优输出电压矢量驱动电机运行.仿真结果表明,所提出的控制方法能有效提升系统对负载扰动的鲁棒性,并有效降低转矩波动,使电机具有良好的动态和静态运行性能.     

Smith predictor design for robust performance

A method is outlined for designing Smith predictor controllers that provide robust performance despite real parameter uncertainties in the process model. Insight into the design process is gained by viewing the Smith predictor from the perspective of internal model control. Performance requirements are written in terms of a frequency-domain weight restricting the magnitude of the closed-loop sensitivity function. A general method for approximating multiple parameter uncertainties by a single multiplicative uncertainty is developed—an exact bound is derived for the magnitude of multiplicative uncertainty used to approximate simultaneous uncertainties in process gain, time-constant, and time-delay. Three different tuning methods are demonstrated; each is applied to a wide range of parameter uncertainties in a first-order with time-delay model. The first tuning method locates loop transfer-function uncertainty regions to test for robust performance—real parameter uncertainties are considered exactly. The second tuning method approximates real parameter uncertainties by multiplicative uncertainty and uses structured singular value analysis to guarantee robust performance. The third is a ‘quick design’ method that considers the unit magnitude crossing of the multiplicative uncertainty. Finally, the Smith predictor controller is compared with the structured-singular-value-optimal controller.     

电动汽车IPMSM滑模观测器速度控制方法

增程式电动汽车在实际运行中容易产生驱动电机内部参数不确定性和外部扰动的问题,制约了控制系统性能的进一步提升,针对此问题开展电动汽车内置式永磁同步电机速度跟踪控制的研究。为电动汽车驱动电机设计了常规的基于扰动上下界的滑模速度控制器。为了抑制抖振,采用滑模观测器对扰动进行观测,将观测结果前馈至控制器内部,对驱动电机中扰动进行补偿,以降低滑模控制器中的抖振。在ECE工况下对基于上下界的滑模控制和基于观测器的控制方案进行了仿真和实验,对速度的跟踪性能和抖振的削弱性能进行了对比,结果显示负载不发生变化时速度跟踪误差由±0.08 km/h缩小到±0.01 km/h,负载发生变化时,速度跟踪误差由11.3 km/h缩小到1.6 km/h。     

伺服电机驱动的连铸结晶器振动系统受限状态下预设性能控制

以伺服电机驱动的连铸结晶器振动位移系统为研究对象,针对系统输入和状态受限问题,考虑系统存在的参数不确定性和负载转矩扰动影响,设计一种基于观测器的预设性能自适应控制器.首先,针对系统存在的参数不确定性、负载转矩扰动等问题,基于Lyapunov函数设计变增益扩张状态观测器,在保证观测精度的同时,削弱峰值现象;其次,考虑状态和输入受限的情况,将预设性能函数与Backstepping技术相结合设计控制器,构建指令滤波器解决“计算膨胀”问题,引入动态补偿量对观测器及受限状态产生的误差进行补偿,并对所设计的控制器进行稳定性分析;最后,通过仿真对比实验验证控制器的有效性.     

TCSC 系统的自适应minimax 干扰抑制控制器设计

针对含有未知外部干扰和不确定参数的非线性晶闸管控制串联补偿器(TCSC) 系统, 提出一种L₂增益干扰抑制算法. 将minimax 方法引入耗散Hamilton 系统, 消除了不等式假设条件的约束; 构造检验函数, 推算出系统所能承受的最大干扰程度, 降低了传统干扰处理方法的保守性; 采用参数映射方法设计自适应律, 提高了参数跟踪效率. 最后通过机械功率和对地短路故障的仿真结果表明了所提出的控制方案能够有效改善系统的暂态性能.

     

基于DRFNN的共振频率自适应反推控制

针对共振破碎机频率控制系统的不确定性问题,提出基于动态递归模糊神经网络的自适应反推控制策略。建立了破碎机频率控制系统的数学模型,在忽略不确定性项的前提下,设计了基于自适应Back-stepping方法控制律。其次将电液系统中影响频率控制性能的不确定性因素定义为待估计项,采用动态递归模糊神经网络对其进行实时估计,给出了基于动态递归模糊神经网络的参数自适应律,并通过了Lyapunov的稳定性分析。仿真实验和车载测试结果表明,对于系统参数的不确定性,该方法具有较好地频率控制性能。     

一种分析和设计Sm ith 预估器的新方法及其应用

针对积分、一阶和二阶稳定与不稳定带长时滞的过程,给出了Smith预估器的分析和设计新方法,使其设定值的响应从负载干扰响应中分离出来,并用参数辨识的方法解决了在实际中难以得到过程精确的数学模型和控制器离散化的问题。模拟仿真和离散化系统仿真都达到了满意的效果,表明该方法是工程中很有前途的一种应用方法。     

Identification of discrete-time output error model for industrial processes with time delay subject to load disturbance

In this paper, a bias-eliminated output error model identification method is proposed for industrial processes with time delay subject to unknown load disturbance with deterministic dynamics. By viewing the output response arising from such load disturbance as a dynamic parameter for estimation, a recursive least-squares identification algorithm is developed in the discrete-time domain to estimate the linear model parameters together with the load disturbance response, while the integer delay parameter is derived by using a one-dimensional searching approach to minimize the output fitting error. An auxiliary model is constructed to realize consistent estimation of the model parameters against stochastic noise. Moreover, dual adaptive forgetting factors are introduced with tuning guidelines to improve the convergence rates of estimating the model parameters and the load disturbance response, respectively. The convergence of model parameter estimation is analyzed with a rigorous proof. Illustrative examples for open- and closed-loop identification are shown to demonstrate the effectiveness and merit of the proposed identification method.     

On the modified Smith predictor for controlling a process with anintegrator and long dead-time

A dead-time compensator for controlling higher-order processes with integral action and long dead-time is proposed. Tuning formulas are derived. If the velocity gain and the dead-time are estimated experimentally, only one parameter, the time constant defining the speed of the closed-loop setpoint response, has to be tuned manually. The same setpoint response is obtained as in the modified Smith predictor, while the load disturbance rejection is considerably faster     

带有控制受限的卫星编队飞行六自由度自适应协同控制

针对存在参数不确定性以及干扰的卫星编队飞行六自由度协同控制问题,提出了一种满足控制输入有界的自适应L2增益干扰抑制控制方法.该方法首先在不考虑干扰的条件下,针对卫星编队六自由度协同运动模型存在参数不确定性提出了一种自适应协同控制器;接着,考虑到系统存在干扰,进一步设计了具有L2增益干扰抑制能力且满足输入有界条件的自适应...     

Modified Smith predictor with a robust disturbance reduction scheme for linear systems with small time delays

This paper presents a robust disturbance reduction scheme using an artificial neural network (ANN) for linear systems with small time delays. It is assumed that the nominal linear systems are stable, minimum phase and relative degree one systems. The proposed structure is an integration of a modified Smith predictor and an ANN‐based disturbance reduction scheme. Unlike other disturbance rejection methods, the proposed approach does not require information about unknown load disturbance frequencies. An ANN is used to approximate the unknown load disturbances and to enhance the robustness of the proposed disturbance reduction scheme against modelling errors in the estimated time delay and the process model. Connective weights of the ANN are trained on‐line using a back‐propagation algorithm until uncertainties resulting from unknown load disturbances and modelling errors are minimized. The simulation results show the effectiveness of the presented disturbance reduction scheme for controlling linear delay systems subjected to step or periodic unknown load disturbances.     

A two degree of freedom level control

A two degree of freedom control is proposed for liquid level control. The load estimation is achieved in an indirect manner. Only one design parameter is required for the load estimation. As for the feedback loop, a P-only feedback action is employed. It is equivalent to a P control at disturbance free condition and becomes a PI controller under load disturbance. Steady-state characteristics, dynamic properties and robustness issues are explored. Design procedures are also proposed. A surge tank example is used to illustrate the performance of the proposed control. The results show that the two-degree of freedom control gives good nominal performance and is robust with respect to modeling errors. Improved performance are also observed for systems with time delay or right-half-plane zero.