Low-loss 7-bit S-band CMOS passive phase shifter with digital control

This paper presents the design and implementation of a 7-bit S-band digital passive phase shifter using Complementary Metal-Oxide-Semiconductor (CMOS) 65-nm technology in 2.6- to 3.2-GHz frequency band. New switched delay network topology has been used for 5.625° and 2.8°, and modified switched filter topology has been used for implementation of other phase bits to achieve 7-bit performance with low insertion loss and better isolation. The measured results of the fabricated chip show 7-bit performance with an average insertion loss of 11 dB, average root mean square (RMS) phase error of less than 2.0°, average RMS amplitude error of less than 0.6 dB, input matching (S₁₁) better than −7.5 dB, and output matching (S₂₂) better than −14.5 dB across the target frequency band at 50Ω input/output impedance.     

Output‐feedback co‐ordinated decentralized adaptive tracking: The case of MIMO subsystems with delayed interconnections

Exact decentralized output‐feedback Lyapunov‐based designs of direct model reference adaptive control (MRAC) for linear interconnected delay systems with MIMO subsystems are introduced. The design process uses a co‐ordinated decentralized structure of adaptive control with reference model co‐ordination which requires an exchange of signals between the different reference models. It is shown that in the framework of the reference model co‐ordination zero residual tracking error is possible, exactly as in the case with SISO subsystems. We develop decentralized MRAC on the base of a priori information about only the local subsystems gain frequency matrices without additional a priori knowledge about the full system gain frequency matrix. To achieve a better adaptation performance we propose proportional, integral time‐delayed adaptation laws. The appropriate Lyapunov–Krasovskii type functional is suggested to design the update mechanism for the controller parameters, and in order to prove stability. Two different adaptive DMRAC schemes are proposed, being the first asymptotic exact zero tracking results for linear interconnected delay systems with MIMO subsystems. Copyright © 2005 John Wiley & Sons, Ltd.     

Robust adaptive control for unmatched systems with guaranteed parameter estimation convergence

This paper provides a modified model reference adaptive control (MRAC) scheme to achieve better transient control performance for systems with unknown unmatched dynamics, where an adaptive law with guaranteed convergence is introduced. We first revisit the standard MRAC system and analyze the tracking error bound by using L₂‐norm and Cauchy‐Schwartz inequality. Based on this analysis, we suggest a feasible way to compensate the undesired transient dynamics induced by the gradient descent–based adaptive laws subject to sluggish convergence or even parameter drift. Then, a modified adaptive law with an alternative leakage term containing the parameter estimation error is developed. With this adaptive law, the convergence of both the estimation error and tracking error can be proved simultaneously. This enhanced convergence property can contribute to deriving smoother control signal and improved control response. Moreover, this paper provides a simple and numerically feasible approach to online verify the well‐known persistent excitation condition by testing the positive definiteness of an introduced auxiliary matrix. Comparative simulations based on a benchmark 3‐DOF helicopter model are given to validate the effectiveness of the proposed MRAC approach and show the improved performance over several other MRAC schemes.     

一种固定指向多波束天线安装测量技术研究

某固定指向多波束天线由主反射体和馈源系统组成,天线主反射体固定且主波束指向唯一,馈源系统可以沿倾斜轨道运动以匹配不同的卫星。与全动或限动式天线相比,固定指向多波束天线结构指标在追求主反射面具有高精度的表面精度的同时,要保证其主波束指向精度,并实现馈源系统的精确定位。本文提出一种综合运用静态GPS测量系统、全站仪测量系统、激光跟踪仪测量系统、数字工业摄影测量系统等多种空间测量技术的方案。在该多波束天线安装过程中采用此测量方案,主反射面表面精度优于±0.15㎜,主波束指向精度优于±0.0122°,馈源系统定位精度优于±1.5㎜,满足结构安装指标要求。通过多波束天线系统测试电性能指标满足要求,充分验证了该方案的可行性、可靠性、高效率和高精度的特点。     

Design of a static VAR compensator using model reference adaptive control

A novel approach for the design of a static VAR compensator (SVC) is proposed. The SVC, which comprises a fixed capacitor and a thyristor-controlled inductor, can be used to improve generator damping without deterioration in the voltage profile under severe disturbance conditions. In order to achieve better dynamic performance, a supplementary proportional-integral (PI) controller, of which the parameters are determined by eigenvalue assignment, is incorporated in the static VAR compensator. To further improve the damping characteristics over a wide range of operating conditions, an adaptive controller using model reference adaptive control (MRAC) is also developed. Results from the digital simulation of the system subject to a three-phase fault indicate that the MRAC can provide better dynamic performance than the fixed-gain PI controllers.     

陀螺稳定平台伺服系统非线性特性补偿控制

在详细分析导引头陀螺伺服稳定平台系统模型和运行特性的基础上,提出采用带非线性加速度负反馈并联校正环节的变速积分PID控制算法.功能样机试验运行效果表明,该系统具有快速的动态响应和较强的抗非线性干扰能力,满足了设计指标要求.     

Experimental evaluation of combined model reference adaptive controller in a pH regulation process

An experimental evaluation of the combined model reference adaptive control (CMRAC) is presented in this paper. This adaptive control scheme was used to control a relatively complex process like the pH of a solution in a tank reactor at laboratory level. For comparison purposes, some very well‐known control strategies were also implemented, which include PID control and standard model reference adaptive control (MRAC). Tracking and regulation capabilities of the control strategies studied were analysed and compared. Experimental results indicate that CMRAC behaves as well as the standard MRAC and a very well‐tuned PID for a specific and known operating point. Advantages of the adaptive controllers are shown when the operating point changes. Copyright © 2002 John Wiley & Sons, Ltd.     

陀螺稳定平台模糊自调整滑模解耦控制

针对陀螺稳定平台系统中轴系间耦合因素对控制性能的影响,设计了一种模糊自调整滑模解耦控制算法.根据非线性微分几何理论,建立了稳定平台输入输出解耦控制,在此基础之上加入了模型参考滑模控制.所设计的滑模控制律采用了分层结构,在边界层内引入了非线性项,同时边界层厚度由一种模糊自调整方法实时改变,从而有效降低了滑模控制在实际应用中的抖振现象,提高了系统的解耦精确度.通过在某型号电视导引头陀螺稳定平台系统中测试,表明了该解耦控制方法的有效性和可行性;同PID等常用方法相比较,该方法的控制效果明显优于其他控制方法,有效提高了稳定平台系统的鲁棒性和跟踪精确度.     

Lyapunov‐stable discrete‐time model reference adaptive control

Discrete‐time model reference adaptive control (MRAC) is considered with both least squares and projection algorithm parameter identification. For both cases complete Lyapunov proofs are given for stability and convergence. The results extend the approach of Johansson (Int. J. Control 1989; 50 (3):859–869) to include Lyapunov stability for MRAC when the normalized projection algorithm is used for parameter identification. Copyright © 2005 John Wiley & Sons, Ltd.     

Comparison between various control methods for thermal power plant main control system

In thermal power plants, it is important to improve the control accuracy of main steam pressure and temperature and so forth during load up/down. This paper focuses on temperature control, the most difficult aspect of control due to the nonlinearity and long dead time of power plants. We applied control methods such as MRAC, neural network, and long‐range predictive control to the power plant main control system. Each method was evaluated by a simulator using detailed physical models that represent accurately the power plant dynamics. We confirmed that each method can provide proper control, but long‐range predictive control is better than the two other methods. In addition, thermal power plants are so complex that further analysis (e.g., persistently exciting condition, learning method of neural networks) is necessary for the application of theoretical algorithms. © 1999 Scripta Technica, Electr Eng Jpn, 128(3): 72–81, 1999     

Transients in output feedback adaptive systems with observer‐like reference models

This note presents analysis and quantification of transient dynamics in Model Reference Adaptive Control (MRAC) with output feedback and observer‐like reference models. A practical design methodology for this class of systems was first introduced in 1 , 2 , where an output error feedback was added to the reference model dynamics. Here, this design is complemented with an analysis of the corresponding transients. Specifically, it is shown that employing observer‐like reference models in MRAC leads to a trade‐off between achieving fast transient dynamics and using large error feedback gains in the modified reference model. For clarity sake, only systems with matched uncertainties are analyzed, yet the reported results can be extended to a broader class of uncertainties by utilizing MRAC modifications for robustness 3 , 4 . The note ends with a summary of the derived results and a discussion on practical design guidelines for adaptive output feedback controllers with observer‐like reference models. Copyright © 2015 John Wiley & Sons, Ltd.     

Model reference adaptive iterative learning control for linear systems

In this paper, we propose a model reference adaptive control (MRAC) strategy for continuous‐time single‐input single‐output (SISO) linear time‐invariant (LTI) systems with unknown parameters, performing repetitive tasks. This is achieved through the introduction of a discrete‐type parametric adaptation law in the ‘iteration domain’, which is directly obtained from the continuous‐time parametric adaptation law used in standard MRAC schemes. In fact, at the first iteration, we apply a standard MRAC to the system under consideration, while for the subsequent iterations, the parameters are appropriately updated along the iteration‐axis, in order to enhance the tracking performance from iteration to iteration. This approach is referred to as the model reference adaptive iterative learning control (MRAILC). In the case of systems with relative degree one, we obtain a pointwise convergence of the tracking error to zero, over the whole finite time interval, when the number of iterations tends to infinity. In the general case, i.e. systems with arbitrary relative degree, we show that the tracking error converges to a prescribed small domain around zero, over the whole finite time interval, when the number of iterations tends to infinity. It is worth noting that this approach allows: (1) to extend existing MRAC schemes, in a straightforward manner, to repetitive systems; (2) to avoid the use of the output time derivatives, which are generally required in traditional iterative learning control (ILC) strategies dealing with systems with high relative degree; (3) to handle systems with multiple tracking objectives (i.e. the desired trajectory can be iteration‐varying). Finally, simulation results are carried out to support the theoretical development. Copyright © 2006 John Wiley & Sons, Ltd.     

风力发电机独立变桨控制技术系统级优化研究

针对目前独立变桨距风力发电机存在桨叶受力载荷过大、输出功率和电压不稳定的问题,采用模型参考自适应控制方法进行控制器优化,研究了风力发电机独立变桨优化控制问题。讨论了模型参考自适应控制方法下参考模型选取的过程,根据Lyapunov稳定性理论对模型参考自适应控制器进行了设计,并将这一控制器应用在风力发电机的独立变桨距上。仿真结果表明,该控制方法不仅提高了变桨控制器的响应速度和跟踪精度,而且能够稳定输出功率和电压,同时也能够减少各桨叶的拍打震动。模型参考自适应控制器能够应用在风力发电机独立变桨距控制中,控制效果良好。     

平面开关磁阻电机模型参考自适应位置控制

为了提高平面开关磁阻电机的位置精确度,研究一种基于模型参考自适应控制理论的平面开关磁阻电机控制方法。采用最小二乘法辨识了平面开关磁阻电机的线性化模型参数,根据李亚普若夫稳定性理论,以力指令为控制量并采用输入输出变量设计了平面开关磁阻电机模型参考自适应位置控制器,基于dSPACE半实物实时仿真系统,构建了实时在线控制实验平台,进行了平面开关磁阻电机的模型参考自适应位置控制实验。研究表明:基于模型参考自适应控制的平面开关磁阻电机系统能平稳、准确地跟随给定位置,提高了电机位置精确度,验证了提出的平面开关磁阻电机模型参考自适应控制方法的可行性和有效性。     

真空泵用多台屏蔽电机模式切换与位置补偿偏差耦合同步控制

针对真空泵用多台屏蔽电机起动、突加随机扰动、突加周期性负载及单/多电机不同时刻故障停机过程,设计了模式切换与位置补偿偏差耦合同步控制系统,创新性地在速度补偿器中引入位置补偿器,同时在故障瞬间将偏差耦合控制方式切换为主从控制。将所提出的控制系统与传统的虚拟电机控制系统进行了对比。结果表明:当发生单电机故障以及双电机不同时刻故障时,在相同的模式切换和位置补偿条件下,所提出的控制系统位置误差分别为4.6°和4°,在5°的误差允许范围内,而传统虚拟电机控制系统的位置误差分别为15°和20°。     

基于STM32的全方位移动平台设计和控制

为了实现移动平台的全方位移动和避障,设计了一种基于 STM32开发板的移动平台控制系统。该系统利用红外传感器以及无刷电机的差速转动实现循迹,利用超声波传感器进行测距,并通过对收集到的数据信息进行处理与分析实现避障。另设有无线控制模式,当移动平台遇到障碍或处于非循迹轨道上时,操作者可通过摇杆实现对移动平台的方向控制。实验结果表明,移动平台可以自动检测方位并修正,实现无碰撞行驶。     

二自由度鲁棒IMC控制器设计

在航空稳定平台中,为了解决扰动力矩对于视轴稳定性的影响,在鲁棒IMC控制原理的基础上,利用局部干扰观测器思想进行改进。结合二自由度控制思想,通过引入一组与误差量无关的控制器,将扰动抑制和跟踪精度分离,在保证控制系统鲁棒性的前提下,提高了稳定平台的抗干扰能力和稳定跟踪能力。对于本文方法进行了仿真和物理实验,设计实验如下：1）平台外框架不动,内框架以0.5 Hz,1°/s的正弦信号运动;2）外框架以1 Hz,6°/s的正弦信号作为速度扰动,内框架在补偿轴系摩擦力矩的前提下保持稳定。实验结论：二自由度鲁棒内膜控制系统有效的克服了轴系摩擦力矩所带来的影响,使得控制系统具有更好的输入响应特性,并将平台稳定精度从0.03°提升到0.004°,证明了本方法在保证良好输入响应特性的前提下,提高其抗干扰能力。     

光电稳定平台角位移高精度测量方法研究

为了实现对光电稳定平台方位和俯仰框架运动角度的高精度测量,本研究使用了一种新型的非接触式高精度电容传感器。利用偏心原理,合理布置电容式传感器的位置,使方位框架和俯仰框架的几何中心与电容式传感器的检测面旋转中心不重合。当方位框架和俯仰框架分别绕着方位轴和俯仰轴运动时,其检测面与传感器之间的距离会产生变化,通过距离的变化可以测量出方位框架和俯仰框架角度的变化。依据偏心原理设计了一套测量装置,测量结果表明电容式传感器测量的距离值与其对应的角度值有良好的线性度,电容式传感器的测量精度优于15",完全满足光电稳定平台方位框架和俯仰框架角位移的测量要求。     

车载天线稳定平台的光纤陀螺性能评估

"动中通"是现代移动指挥与通信系统的主要特点,通信天线的稳定与指向控制是动中通的重要组成部分,惯性传感器与系统敏感载体的三维姿态变化与位置变化,是实现天线指向控制的关键。光纤陀螺作为一种惯性敏感器,在惯性/组合导航系统应用不断扩展。面向指挥车天线稳定平台应用背景,分析了光纤陀螺的主要指标参数,构建了测试环境对某小型低成本光纤陀螺的性能进行试验评估,从评价结果判断,本陀螺可用于研制接近于导航级精度的指挥车天线稳定平台的惯性组合基准系统。     

基于模型预测前馈的滚转稳定伺服系统控制研究

速率陀螺式滚转稳定平台是一种应用于旋转载体中的惯性稳定装置,不仅要求有较高的位置控制精度,为满足陀螺测量范围,还要求很高的速度控制精度。通过对稳定平台的分析,详细推导了系统的传递函数模型,在PID反馈控制的基础上,设计了由模型预测控制单元组成前馈环节的预测前馈复合控制器。实验结果表明在载体滚转速度快速上升以及大速度稳定滚转情况下,模型预测前馈控制大大提高了稳定平台的控制精度。