Transfigured Loop Shaping Controller and its Application to Underwater Vehicle

A kind of transfigured loop shaping controller is presented in this paper. A transfigured loop shaping system puts a controller K in a feedback loop, while putting the dc gain of the controller K on the reference signal line. It is shown through frequency domain analysis and simulation that a transfigured controller can improve the dynamic behavior of a system. The transfigured loop shaping controller method is simple and effective and corresponds to the mixed sensitivity method of robust control theory, which improves the behavior of a system by iterative tuning of weighting functions. Satisfactory control results are obtained when it is applied to the design of an underwater vehicle. Keywords Loop shaping controller - underwater vehicle - transfiguration Zhang Xianku graduated from Beijing Institute of Clothing Technology, China, in 1990. He received the M. S. degree from Dalian Maritime University (DMU), China, in 1993 and the Ph.D. degree from DMU, in 1998. He is currently a professor at the Laboratory of Simulation and Control of Navigation Systems, Dalian Maritime University. His research interests include ship motion control and robust control.Jin Yicheng graduated from Zhejiang University, China, in 1967. He is currently a professor at the Laboratory of Simulation and Control of Navigation Systems, Dalian Maritime University. His research interests include simulating system of ship steering and visual control.

H_∞Loop Shaping Control for Plasma Vertical Position Instability on QUEST

QUEST has a divertor configuration with a high and a negative n-index, and the problem of plasma vertical position instability control in QUEST is still under extensive study for achieving high efficiency plasma. The instability we considered is that the toroidal plasma moves either up or down in the vacuum chamber until it meets the vessel wall and is extinguished. The actively controlled coils （HCU and HCL） outside the vacuum vessel are serially connected in feedback with a measurement of the plasma vertical position to provide stabilizing control. In this work, a robust controller is employed by using the loop synthesis method, and provides robust stability over a wide range of n-index. Moreover, the gain of the robust controller is lower than that of a typical proportional derivative （PD） controller in the operational frequency range; it indicates that the robust controller needs less power consumption than the PD controller does.

Voltage Generation by Rotating an Arbitrary-Shaped Metal Loop around Arbitrary Axis in the Presence of an Axial Current Distribution

A thin metallic wire loop of arbitrary curvature is rotated with respect to an arbitrary axis of its plane. The device is excited by an electric dipole of infinite length and constant current. The resistance of the loop is computed rigorously as function of the position of the source. In this way, the induced voltage along the wire, under any kind of axial excitation, is given in the form of a superposition integral. The measured response is represented for various shapes of the coil, with respect to the time, the rotation angle and the position of the source. These diagrams lead to several technically applicable conclusions which are presented, discussed and justified.

Loop-Shaping Based Control for Switch Mode DC-DC Power Converters

Renewable energy sources require switching regulators as an interface to a load with high efficiency, small size, proper output regulation, and fast transient response. Moreover, due to the nonlinear behavior and switching nature of DC-DC power electronic converters, there is a need for high-performance control strategies. This work summarized the dynamic behavior for the three basic switch-mode DC-DC power converters operating in continuous conduction mode, i.e. buck, boost, and buck-boost. A controller was designed using loop-shaping based on current-mode control that consists of two feedback loops. A high-gain compensator with wide bandwidth was used in the inner current loop for fast transient response. A proportional-integral controller was used in the outer voltage loop for regulation purposes. A procedure was proposed for the parameters of the controller that ensures closed-loop stability and output voltage regulation. The design-oriented analysis was applied to the three basic switch-mode DC-DC power converters. Experimental results were obtained for a switching regulator with a boost converter of 150 W, which exhibits non-minimum phase behavior. The performance of the controller was tested for voltage regulation by applying large load changes.

Triple Notched Band Characteristics UWB Antenna Using C-Shaped Slots and Slot-Type Capacitively-Loaded Loop (CLL)

Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.

基于非线性修饰和零阶保持器的船舶航向保持控制

[目的]为了解决船舶在海上航行时控制器舵角输出大、打舵频率高、控制速度较慢以及控制精度较低的问题,利用三阶闭环增益成形算法设计鲁棒控制器。[方法]首先,利用三阶闭环增益成形算法设计出线性鲁棒控制器,然后,在控制策略中加入双曲正切非线性修饰以及零阶保持器,在不同海况下对该控制器的性能进行仿真实验。[结果]仿真结果表明,相比于基于非线性修饰的传统PID控制器,在一般海况下,所提控制器在延迟时间、控制精度以及能量输出上分别改进了36%,14%和32%;在恶劣海况下,分别改进了27%,7%和16%。此外,不同海况下该控制器的仿真结果都具有稳定的舵角输出,并可以较快地稳定在临界值附近,证明了其具有较好的鲁棒性。[结论]改进的控制器符合工程实践,对于智能船舶的控制具有较好的应用参考价值。

尖牙反[牙合]矫治人字形和T形曲组合正畸弓丝矫治力建模

固定矫治技术是治疗牙齿反[牙合]最为有效的矫治手段,主要通过正畸弓丝释放的矫治力来达到反[牙合]矫治中的矫治空间预留、反[牙合]牙齿回收的目的。在牙齿反[牙合]畸形中,尖牙反[牙合]是最为常见的牙齿反[牙合]畸形,常使用人字形和T形组合曲关闭上颌牙列间隙。本文旨在正畸治疗前量化人字形和T形组合曲释放矫治力的情况,为正畸医师提供尖牙反[牙合]矫治的理论参考。分析人字形和T形组合曲的形变过程,将其形变过程分为弹性形变和弹塑性形变两类,并对两种形变下的矫治力微分方程进行了构建,将其释放的矫治力分为闭隙矫治力和倾覆矫治力两种,完成了人字形和T形组合曲理论模型的建立,其次对有限元仿真值与理论值的误差率进行计算,得到闭隙矫治力仿真值与理论值的误差率在0.43%~8.33%之间,倾覆矫治力的仿真值与理论值的误差率在2.13%~9.76%之间,搭建实验测量平台得到了闭隙矫治力实验值与理论值误差率为0%~9.30%、倾覆矫治力实验值与理论值的误差率为0%~9.76%,实验测量数据与理论值具有相同的非线性变化趋势,验证了人字形和T形组合曲理论预测模型的正确性,该模型能帮助医师在治疗前对正畸力进行详细的定量分析,从而为个性化治疗方案的制定提供依据,更好地满足患者需求。

Robust control of isopropyl benzene production process using H_(∞) loop shaping control scheme

This paper discusses robust control strategy for isopropyl benzene production process using the method of loop shaping H_(∞) technology.This cumene production process is a part of phenol plant in HOCL,Kochi.H_(∞) control of the propylene concentration is done here.The H_(∞) controller is derived from the linearised model of the reactor.The optimal H_(∞) controller is obtained by simplifying two algebraic Riccati equations.The proposed PID-like H_(∞) controller provides a single tuning parameter which makes the controller design more accurate.The proposed controller has been compared with other robust controllers like H_(2) and LQR.The H_(∞) controller is found to be superior in a wide frequency range and has a feature of low distortion and good regulating performance.The reactor model has been developed in COMSOL Multiphysics with the parameters obtained from HOCL plant,Kochi.The model extracted is reduced using model order reduction for the controller design.

一种基于双重非线性正反馈的节能降碳航向保持控制方法

[目的]为了解决船舶航向保持过程中舵角幅值过大以及舵角变换率过高而导致能耗过大的问题,提出一种基于双重非线性正反馈的节能降碳航向保持控制方法。[方法]采用闭环增益成形算法(CGSA)设计控制器,引入双重非线性反馈算法,通过双极性S函数与反正切函数的结合降低舵角幅值与操舵频率,最后使用正反馈的方法实现整个控制系统的控制。[结果]仿真结果表明,在6级海况和8级海况下,采用所提出的双重非线性反馈控制方法,反映舵机能耗的综合节能评价指标分别改进了31.53%和18.63%。[结论]验证了双重非线性反馈在降低舵机能耗、减少船舶航行过程中碳排放方面具有较好效果,以及正反馈和负反馈的等价控制效果。所提方法为船舶航向保持控制的研究提供了较好的应用参考价值。

形状可调的Loop细分曲面渐进插值方法

针对Loop细分无法调整形状与不能插值的问题,提出了一种形状可调的Loop细分曲面渐进插值方法。首先给出了一个既能对细分网格顶点统一调整又便于引入权因子实现细分曲面形状可调的等价Loop细分模板。其次,通过渐进迭代调整初始控制网格顶点生成新网格,运用本文的两步Loop细分方法对新网格进行细分,得到插值于初始控制顶点的形状可调的Loop细分曲面。最后,证明了该方法的收敛性,并给出实例验证了该方法的有效性。

海豚头气动外形导弹主动段过载驾驶仪设计

针对海豚头气动外形导弹主动段飞行过程中存在快速变化的俯仰干扰力矩导致驾驶仪过载指令不跟随的问题,研究了一种基于自适应控制的三回路过载驾驶仪在线调参方法。首先,对纵向短周期下的导弹动力学进行建模,建立三回路过载驾驶仪状态方程,在标称状态下采用极点配置对三回路过载驾驶仪的控制参数进行设计;其次,将标称状态下的驾驶仪视为参考模型,采用模型参考自适应方法,通过设计Lyapunov函数对自适应更新律进行设计。为了增强在建模不确定条件下自适应算法的稳定性,引入投影算子和死区的概念;最后,在气动拉偏条件下对海豚头气动外形导弹的主动段进行三回路自适应过载驾驶仪指令跟踪仿真。仿真结果表明,三回路自适应过载驾驶仪在海豚头气动外形导弹的主动段具有较好的动态跟踪特性。

基于仿生树形相变循环散热技术研究及变频空调应用

伴随环境温度升高,空调制冷量需求也会逐步增高,从而引发变功率模块发热严重,导致其内部芯片无法良好散热。通常采用压缩机降频工作方法保证电控板安全,但该方法的缺点是温度越高,空调制冷能力越差。针对该缺点,提出一种仿生树形的单向相变循环传热方法,开发了一款单向循环相变风冷散热器,通过焓差室测试,实现了散热器进风口温度62℃时,变频功率模块温度可以降低8℃以上,防止压缩机强制降频造成制冷量衰减。

Effects of Shape of Crowders on Dynamics of a Polymer Chain Closure

Using 3D Langevin dynamics simulations, we investigate the effects of the shape of crowders on the dynamics of a polymer chain closure. The chain closure in spherical crowders is dominated by the increased medium viscosity so that it gets slower with the increasing volume fraction of crowders. By contrast, the dynamics of chain closure becomes very complicated with increasing volume fraction of crowders in spherocylindrical crowders. Notably, the mean closure time is found to have a dramatic decrease at a range of volume fraction of crowders 0.36-0.44. We then elucidate that an isotropic to nematic transition of spherocylindrical crowders at this range of volume fraction of crowders is responsible for the unexpected dramatic decrease in the mean closure time.

Industrial shape detecting system of cold rolling strip

A high-precision shape detecting system of cold rolling strip is developed to meet industrial application, which mainly consists of the shape detecting roller, the collecting ring, the digital signal processing （DSP） shape signal processing board and the shape control model. Based on the shape detecting principle, the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface. Based on the DSP technology, the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing. The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill. The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 1 after the close loop shape control is input.

An experimental study of in-plane arch-shaped dampers

As an effort to minimize material utilization, seismic steel dampers designed to deform inelastically in an in-plane flexural mode have attracted serious attention recently. This paper presents a new type of metallic yielding damper referred to as the in-plane arch-shaped damper modified from its portal frame-shaped counterpart by replacing the straight beam with a circular arch to minimize the effects of stress concentration and warping, and therefore to avoid premature failure. Component tests of both the portal frame-shaped and arch-shaped in-plane dampers were conducted for comparison. Hysteresis loops obtained from the component tests under cyclic loads indicate substantial improvement on the energydissipative characteristics of the proposed damper. Moreover, seismic performance assessment of the proposed damper was carried out further via shaking table tests of a five-story model frame. Encouraging results have been achieved in terms of acceleration reduction, damping enhancement and peak suppression of the frequency response functions, suggesting the potential of the proposed device to be used in earthquake-resisting systems.

Noise behaviors of a closed-loop micro-electromechanical system capacitive accelerometer

The noise of closed loop micro-electromechanical systems(MEMS) capacitive accelerometer is treated as one of the significant performance specifications.Traditional optimization of noise performance often focuses on designing large capacitive sensitivity accelerometer and applying closed loop structure to shape total noise,but different noise sources in closed loop and their behaviors at low frequencies are seldom carefully studied,especially their behaviors with different electronic parameters.In this work,a thorough noise analysis is established focusing on the four noise sources transfer functions near 0 Hz with simplified electronic parameters in closed loop,and it is found that the total electronic noise equivalent acceleration varies differently at different frequency points,such that the noise spectrum shape at low frequencies can be altered from 1/f noise-like shape to flat spectrum shape.The bias instability changes as a consequence.With appropriate parameters settings,the 670 Hz resonant frequency accelerometer can reach resolution of 2.6 μg/(Hz)1/2 at 2 Hz and 6 μg bias instability,and 1300 Hz accelerometer can achieve 5μg/(Hz)1/2 at 2 Hz and 31 μg bias instability.Both accelerometers have flat spectrum profile from 2 Hz to 15 Hz.

装配式混凝土U型钢筋环扣的连接长度

为研究装配式混凝土U型钢筋环扣连接的搭接长度,制作了1个现浇梁柱节点试件和3个不同搭接长度的U型钢筋环扣连接节点对比试件,进行低周反复拟静力试验,观察各试件的破坏模式,研究其滞回性能、承载力、变形能力及钢筋的应力发展过程,分析装配式混凝土U型钢筋环扣连接的合理搭接长度。结果表明:装配式节点试件承载力高于现浇节点试件;不同搭接长度试件的延性及耗能能力有所不同,搭接长度的增长有利于试件承载力、延性和耗能能力等抗震性能的提升;基于试验结果,拟合回归了U型钢筋环扣连接的合理搭接长度,对装配式混凝土U型钢筋环扣连接节点的优化设计提出了建议。

Drag of a D-shaped bluff body under small amplitude harmonic actuation

Open-loop flow control method was used to affect the development of a turbulent wake behind a D-shaped bluff body. Loud speakers were embedded inside the bluff body to produce two zero-net-mass- flux jets through 2 mm-wide span-wise slots located along the upper and lower edges on the rear wall. The drag forces for different actuation amplitudes （Cμ, the ratio between the momentum of the actuating jets and the moment deficit caused by the bluff body） and frequencies （StA） were examined. The effects of the phase difference in the two jets （0 and π） were also studied. It was found that when Cμ was 0.1%, a drag reduction up to 5% was achieved when the velocities of the two jets varied in phase at a frequency of 5tA = 0.16. When the velocities of the two jets varied π out of phase, significant drag increase was observed.

超弹性NiTi合金夹芯体的冲击性能分析

基于机械形状记忆合金(SMAs)模型的有限元分析方法,分析了一定位移载荷下的NiTi合金夹芯体单元,得到夹芯体结构的应力和腹板数关系曲线、应力和应变曲线、马氏体的体积分数分布图、功和能时程关系、冲击力时程曲线等。结果表明:腹板不同的结构应力相差1178 MPa,当结构的腹板长宽比10≤l/b≤60时,结构的安全性和经济性分别提高5倍和降低40%,此外,材料的马氏体转变和主应力有直接关系,结构的应力-应变曲线耗能迟滞环面积为5.9(位移70 mm载荷),且随变形增加耗能迟滞环增大到10.3(位移100 mm载荷),产生的较大非线性变形可以完全自动恢复。结构具有至少8%可恢复应变的超弹性、抗冲击性和耗能能力。

涡轴发动机时延鲁棒串级PI控制器设计

针对涡轴发动机分布式控制系统中存在时延导致系统性能退化的问题,利用线性矩阵不等式(LMI)方法设计了时延鲁棒串级PI控制器。先利用内模控制(IMC)方法得到涡轴发动机串级控制器内、外环的PI控制器结构;再利用频域回路成形的方法给出保证系统具有期望性能的LMI形式约束条件;利用梯度近似的方法通过劳斯-赫尔维茨判据得到保证系统稳定的控制器参数约束条件;最后,在基于TrueTime的涡轴发动机分布式非线性仿真平台上进行数字仿真。仿真结果表明:在0.04 s时延条件下,当功率需求下降5%时,系统的调节时间小于5 s,功率涡轮转速超调不超过0.5%,且其最大燃油变化率只有传统串级PI控制系统的67%;设计的控制器能有效应对涡轴发动机分布式控制系统中存在的时延问题,同时能够以更小的代价保证系统具有期望的性能。