The number of least degrees of freedom required for a polarization controller to transform any state of polarization to any other output covering the entire Poincar sphere

Using two typical types of polarization controller, this paper analyses theoretically and experimentally the fact that it is necessary to adjust at least three instead of two waveplates in order to transform any state of polarization to any other output covering the entire Poincar6 sphere. The experimental results are exactly in accordance with the theory discussed in this paper. It has corrected the conventional and inaccurate point of view that two waveplates of a polarization controller are adequate to complete the transformation of state of polarization.

Modified Two-Degrees-of-Freedom Internal Model Control for Non-Square Systems with Multiple Time Delays

A modified two-degrees-of-freedom( M-TDOF) internal model control( IMC) method is proposed for non-square systems with multiple time delays and right-half-plane( RHP) zeros. In this method,pseudo-inverse is introduced to design the internal model controller,and a desired closed-loop transfer function is designed to eliminate the unrealizable factors of the derived controller. In addition,set-point tracking and load-disturbance rejection of each process are separately controlled by two controllers. The simulation results show that in addition to high decoupling performance and robustness,the proposed control method also effectively improves loaddisturbance rejection and simultaneously optimizes the input tracking performance and disturbance rejection performance by selecting the parameters of controllers. Furthermore,the higher tolerance of model mismatch is achieved in this paper.

Temperature Control Based on Fuzzy Logic Two-degree-of-freedom Smith Internal Model

According to the characteristics of the large time delay,nonlinearity and the great inertia of temperature control system in biomass pyrolysis reactor,a two-degree-of-freedom Smith internal model controller based on fuzzy control is proposed.Firstly,the mathematical model of the temperature control system is established by using the step response method,and then the two-degree-of-freedom Smith internal model controller is designed,and the good tracking performance and disturbance suppression performance can be obtained by designing the set value tracking controller and interference rejection capability.Secondly,the fuzzy control algorithm is used to realize the on-line tuning of the control parameters of the two-degree-of-freedom Smith internal model algorithm.The simulation results show that,compared with the traditional internal model control,fuzzy internal model PID control and two-degree-of-freedom Smith internal model control,the algorithm proposed in this paper improves the influence of lag time on the control system,realizes the separation control of set point tracking and anti-jamming performance and the self-tuning of control parameters,and improves the control performance of the system.

Design and Development of a Competitive Low-Cost Robot Arm with Four Degrees of Freedom

The main focus of this work was to design, develop and implementation of competitively robot arm with en- hanced control and stumpy cost. The robot arm was designed with four degrees of freedom and talented to accomplish accurately simple tasks, such as light material handling, which will be integrated into a mobile platform that serves as an assistant for industrial workforce. The robot arm is equipped with several servo motors which do links between arms and perform arm movements. The servo motors include encoder so that no controller was implemented. To control the robot we used Labview, which performs inverse kinematic calculations and communicates the proper angles serially to a microcontroller that drives the servo motors with the capability of modifying position, speed and acceleration. Testing and validation of the robot arm was carried out and results shows that it work properly.

Programming Methods for 6-Degree of Freedom Robot Teaching

In this paper, programming method for industrial robot teaching and composing of robot language system is described. Through the RBT - 6T/S01S as an example,the program and instruction function of the robot language are summarized. The compo- sition of RBT - 6T/S01S robot system is studied,and the programming of robot clamping and assembly parts teaching is made.

Set-point Filter Design for a Two-degree-of-freedom Fractional Control System

This paper focuses on a new approach to design(possibly fractional) set-point filters for fractional control systems.After designing a smooth and monotonic desired output signal,the necessary command signal is obtained via fractional input-output inversion.Then,a set-point filter is determined based on the synthesized command signal.The filter is computed by minimizing the 2-norm of the difference between the command signal and the filter step response.The proposed methodology allows the designer to synthesize both integer and fractional setpoint filters.The pros and cons of both solutions are discussed in details.This approach is suitable for the design of two degreeof-freedom controllers capable to make the set-point tracking performance almost independent from the feedback part of the controller.Simulation results show the effectiveness of the proposed methodology.

Robust <i>H</i>_∞Controller for High Precision Positioning System, Design, Analysis, and Implementation

In this paper, a systematic robust control design and analysis for a single axis precise positioner is presented. The effects of uncertainties on closed-loop stability and performance are considered in the H∞ robust controllers design. v-gap metric is utilized to validate the intelligently estimated uncertainty. The robust controllers are formulated within the frame- work of the standard H∞ mixed sensitivity optimization problem. Furthermore, a specially designed integral-H∞ and two-degree-of-freedom 2 DOF H∞ controllers are developed to provide improved robust performance and resolution properties. It is shown that the proposed design schemes are very effective for robust control and precise tracking performance of the servo positioning system.

H-Infinite Controller Design of Singular Networked Control Systems

This paper investigates the H∞ controller design method for a class of singular networked control systems (SNCS) based on the singular plant. In view of the network-induced delay less than or equal to a sampling period, finite external disturbance, clock-driven sensors, event-driven controller and actuators as well as impulse behavior and structural instability of singular plants, the H∞ controller design method of SNCS with state feed- back way and dynamic output feedback way is investigated respectively by means of the linear matrix inequality method. The existence condition of H∞ control law, the solving approaches of H∞ controller parameters and disturbance attenuation degree are presented. Finally, a simulation example is given to illustrate the effectiveness and feasibility of the presented method.

Empowerment in chronic wound care——exploring the scope for patient contribution

Objective:In this study,we investigated the concept of empowerment in chronic wound care and propose to facilitate patient control by making use of degrees of freedom(DOF):that is,shaping of everyday wound care tasks initiated by patients and based on their wishes,mostly in terms of patients executing treatment steps,requesting or directing health care professionals to under take changes,or modifications of internal states.Methods:As a first step,we conducted a systematic literature search,followed by an inductive form of qualitative content analysis,which resulted in the identification of 5 dimensions as main elements of empowerment:education and shared decision making,adherence to self-care behaviors,responsibility and control,general call for empowerment,and DOF.However,the latter are noticeably absent in the literature.To investigate patients'freedom in shaping the wound care process,we conducted a second literature search.Results:A number of possibilities for patients to influence the wound care process could be identified,but experimental or clinical evidence about their effects is missing,their variety is limited,and they are only inadequately described.Conclusions:However,DOF should be an indispensable aspect of genuine empowerment,since they allow patients to occupy the role of the agent in the treatment process and give rise to the subjective experience of feeling empowered.Thus,in the third part,we develop a research proposal on how to investigate and include DOF in the clinical practice of wound care.Finally,limitations about implementations are discussed(e.g.,patients being reluctant to overcome their passive role,resulting in frustration for health care professionals).

永磁直线伺服系统的速度H_∞控制器优化设计

对永磁直线伺服系统的速度H∞控制器提出优化设计,建立了基于模型匹配二自由度系统的状态空间模型,并将速度控制器设计归结为标准的H∞控制问题;用线性矩阵不等式法得到输出反馈g次优H∞控制器,以保证直线系统的鲁棒性。仿真和实验结果表明,用该方法设计的直线伺服系统能够很好的抑制扰动和跟踪给定。

基于H_∞范数优化的干扰观测器的鲁棒设计

研究干扰观测器的鲁棒优化设计方法,应用H∞范数定义干扰观测器的优化性能评价函数,把低通滤波器的设计问题转换为H∞闭环回路成形问题.通过适当处理相对阶次条件等约束,把带有约束的回路成形问题转换成无约束的H∞标准问题,然后利用H∞标准问题的求解算法设计滤波器.此外,探讨了性能与频率加权函数的关系,并在此基础上提出了加权函数的选取方法.实验结果证明该方法设计简单,且具有最优性和系统性.

数控转台直接驱动回转送进系统的鲁棒2自由度H_∞控制

为使直接驱动回转送进系统具有良好的抗扰性能及速度指令跟踪性能,采用基于模型匹配鲁棒2自由度控制结构,设计一个H∞速度控制器。H∞速度控制器使系统对负载扰动及自身参数变化具有较强鲁棒性,同时采用鲁棒2自由度结构,并考虑模型匹配问题,是为了提高系统对速度信号的渐近跟踪性能及响应速度,可以解决抗干扰性能和快速跟踪性能之间的矛盾。仿真结果及分析表明,所提出的鲁棒2自由度H∞速度控制器可以保证高精度直接驱动转台回转送进系统的鲁棒性和精确速度跟踪。

基于两自由度H_∞控制策略的泵控液压系统研究

针对泵控液压系统存在的控制精度低和鲁棒性差等问题,提出一种两自由度H∞控制策略。根据泵控液压控制系统的工作原理,采用电液模块功能分区的方法构建其数学模型;引入PID控制器作为串联校正函数,提高系统的响应速度,同时设计反馈控制器及前置滤波器提高系统的跟踪精度和鲁棒性;在泵控液压系统的物理模型上对两自由度H∞控制器进行仿真研究,仿真结果表明所设计的控制器具有良好的跟踪精度和鲁棒性,并对其进行实验研究。实验结果表明,与PID控制器相比,采用两自由度H∞控制器时系统的跟踪误差从3.84%-4.64%降低至0.22%-0.42%,同时对外界扰动具有更好的鲁棒性。可见,所提出的两自由度H∞控制器可用于复杂工况下泵控液压系统的实际控制。

基于互质因子分解的感应电能传输系统双自由度H_∞控制

在感应电能传输(IPT)系统中,互感摄动和负载动态变化等问题严重影响着系统输出性能及稳定性要求。首先,基于SP-IPT系统的广义状态空间平均模型,分析系统的开环特性及参数扰动输出特性;然后,采用互质因子分解方式对存在右半平面零点的SP-IPT系统摄动模型进行描述;在此基础上,选择并定义双自由度H_∞鲁棒控制的输入输出变量,推导出所对应广义对象的状态空间实现;最后,基于计算出的双自由度H_∞鲁棒控制器进行仿真分析与实验验证。结果表明,在双自由度H_∞鲁棒控制作用下,虽然闭环摄动系统的动态响应特性可能会偏离期望指标,但却能有效抑制互感及负载摄动对预设参考输入稳态跟踪特性的影响,满足系统鲁棒稳定性要求。

典型二阶积分对象的鲁棒H_∞ PID控制器的解析设计

针对工业中常见的具有积分和时滞特性的二阶过程对象,根据鲁棒控制H∞性能指标提出了一种解析设计PID控制器的新方法,并给出了闭环控制系统保证内稳定的充分必要条件.通过在闭环系统给定点设置低通滤波器来达到二自由度控制,从而优化闭环系统的标称性能.通过仿真实例验证了该方法的优越性.

一种基于H_∞优化的内模控制Anti-windup设计方法

针对被控对象控制输入发生饱和时对内模控制性能和稳定性的不利影响。分析了二自由度内模控制结构具有抗饱和特性的原因。提出了一种抗饱和,跟踪与干扰补偿解耦的三自由度内模控制结构。其中抗饱和控制器基于H∞优化理论综合,小增益定理保证全局稳定性。仿真表明了算法有较好的抗饱和及干扰补偿能力,鲁棒性较强。

永磁直线伺服系统二自由度H_∞控制器设计

对永磁直线伺服系统速度提出基于模型匹配的二自由度H∞动态控制器设计。将二自由度控制与H∞控制相结合,在建立模型匹配二自由度H∞控制系统状态空间模型的基础上,将直线伺服系统的速度动态控制器设计问题归结为标准的H∞控制问题,通过求两个Riccati方程的解得到H∞控制器,以保证永磁直线伺服系统的鲁棒性。仿真实验结果表明,用该方法设计的永磁直线伺服系统具有良好的抑制扰动和跟踪给定的效果,满足数控机床及机器人等高精度系统对直线伺服速度控制的要求。

基于内模原理的轧机传动机电振动H_∞控制

轧机驱动电机与轧辊间采用长轴连接,连接轴刚度有限,因此在带材高速轧制时,常规电流、转速双闭环控制易产生机电振动和断带现象。为了抑制机电振动,保证对干扰有良好的动态抑制作用且无静态扰动误差,同时使系统具有鲁棒稳定性,将内模原理与H∞控制理论相结合,通过选取适当的加权函数,设计了轧机主传动系统机电振动鲁棒控制器,为了能方便地在实际工程中实现复杂的H∞控制器,采用PID控制器逼近所得高阶控制器。同时为了改善控制系统的跟踪性能,在H∞控制器的基础上设计了两自由度控制器,有效减小了系统的超调。仿真研究结果表明:该方法不仅有效抑制了轧机主传动系统的机电振动,而且减小了轧制负荷扰动引起的动态速降。

基于H_∞控制理论的二自由度内模控制器设计

内模控制可以较好地解决跟踪问题 ,但是如果存在标称模型与实际模型失配的问题 ,跟踪性能可能受到破坏。常规的内模控制在碰到对象模型失配时 ,可通过设计一个滤波器来消除模型失配造成的影响 ,但是滤波器的设计并没有一定准则。文中给出一种基于H∞ 控制理论的二自由度内模控制器设计方法 ,主要考虑了标称模型与实际模型的失配性 ,将跟踪问题转化成一个标准的H∞ 控制问题。该二自由度控制器由滤波器和反馈控制器组成。仿真结果表明了此控制器的有效性。

一类不确定对象的两自由度H_∞控制

本文针对具有输出端乘性不确定性这一类对象 ,推导出了在两自由度H∞ 控制结构中 ,为使系统同时具有稳定鲁棒性和性能鲁棒性 ,两个控制器应满足的一个充分条件 ;在此基础上将两自由度H∞ 控制问题转化为标准控制H∞ 问题 ,给出了一种两自由度H∞