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.

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.

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.

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.

Contribution to the Control and Command of a Quadrirotor with Six Degrees of Freedom in an Urban Environment

The objective of this article is to make a contribution relating to the modeling, control, simulation and stabilization of a complex system, with six degrees of freedom of a particular drone which presents many advantages and challenges. On the technological, military, political and other levels with an enormous and beneficial social contribution, it is a quadrotor which is a nonlinear, strongly coupled and unstable system. Such a structure is difficult to master, because the control is multivariable in the sense that six degrees of freedom are to be controlled simultaneously and operating in an environment subject to disturbances. Two commands, in particular Backstepping and PID, will be applied to obtain the stabilization of the quadcopter at the desired values, in attitude and in altitude. This article presents the comparative results of the performance of the quadcopter under the two controls. The effect of the parameters of each command on the response time of the system is elucidated under the Matlab/Simulink environment. For a simulation time of up to 10 seconds minimum with a less good response time of almost 2 seconds for the PID control, these results prove the robustness of the Backstepping command.

基于改进麻雀优化PID的波浪补偿控制方法

随着海上风电“十四五”规划的不断推动,在深远海域对兆瓦级大功率海上风机的需求量随之增加,其规模也在不断扩大。但是,在吊运、安装等海上工作过程中,复杂海浪对船舶产生的持续影响导致风机安装的精度和效率大幅下降,甚至会对人员安全以及财产造成重大损失。在深远海域复杂海况下对工程船舶进行有效的波浪补偿,可提供稳定的作业环境以保证精准高效地完成各项工作,因此,本文提出了一种基于改进麻雀优化PID的波浪补偿控制方法并将其应用于Stewart补偿平台。首先,建立波浪补偿平台动力学以及运动学反解模型,并设计正解模型迭代求解算法。随后,使用PID进行波浪补偿控制,并通过麻雀搜索算法优化参数。接着,采用Circle混沌映射对其进行初始化分布,以解决初始化不均匀的问题;并采用动态自适应加权、柯西突变以及反向学习以提升算法全局寻优能力。最后,生成4~6级海况下的某工程船运动数据作为系统输入,利用MATLAB和Simulink软件平台搭建模型进行补偿控制验证,并在Stewart硬件平台上做补偿试验。结果表明,改进麻雀搜索算法具有较快的收敛速度、较高的精度和更好的寻优能力,优化后的PID控制方法更适合用于复杂海况下波浪补偿平台的控制优化,可为大功率海上风机安装的补偿平台控制系统设计提供参考。

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.

Adaptive Control Based on Neural Networks for an Uncertain 2-DOF Helicopter System With Input Deadzone and Output Constraints

In this paper, a study of control for an uncertain2-degree of freedom(DOF) helicopter system is given. The2-DOF helicopter is subject to input deadzone and output constraints. In order to cope with system uncertainties and input deadzone, the neural network technique is introduced because of its capability in approximation. In order to update the weights of the neural network, an adaptive control method is utilized to improve the system adaptability. Furthermore, the integral barrier Lyapunov function(IBLF) is adopt in control design to guarantee the condition of output constraints and boundedness of the corresponding tracking errors. The Lyapunov direct method is applied in the control design to analyze system stability and convergence. Finally, numerical simulations are conducted to prove the feasibility and effectiveness of the proposed control based on the model of Quanser's 2-DOF helicopter.

基于广义积分器二自由度PID控制的LCL逆变器

传统有源阻尼控制可抑制LCL逆变器谐振,但需要增加额外的电压或电流传感器。为此,提出了一种无需额外传感器的基于广义积分器的LCL并网逆变器单电流反馈二自由度PID控制(GI-2DoF-PID),GI-2DoF-PID比例积分环节实现并网电流无静差跟踪,而基于广义积分器的微分环节则增强LCL逆变器的阻尼特性。推导了控制系统的传递函数,分析了其稳定裕度与动态特性,提出跟踪和抗扰动优化的参数设计原则并选取了合适的控制参数。最后,构建了基于PLECS系统仿真模型,仿真结果表明:基于GI-2DoF-PID控制的LCL并网逆变器可以有效抑制谐振;电网电压严重畸变时,其满载并网电流畸变率仅为3%,远低于国家标准的要求;当系统从半载跳变到满载时,系统超调量低,响应速度快。

A PID Tuning Approach for Inertial Systems Performance Optimization

In the practice of control the industrial processes, proportional-integral-derivative controller remains pivotal due to its simple structure and system performance-oriented tuning process. In this paper are presented two approaches for synthesis the proportional-integral-derivative controller to the models of objects with inertia, that offer the procedure of system performance optimization based on maximum stability degree criterion. The proposed algorithms of system performance optimization were elaborated for model of objects with inertia second and third order and offer simple analytical expressions for tuning the PID controller. Validation and verification are conducted through computer simulations using MATLAB, demonstrating successful performance optimization and showcasing the effectiveness PID controllers’ tuning. The proposed approaches contribute insights to the field of control, offering a pathway for optimizing the performance of second and third-order inertial systems through robust controller synthesis.

模糊2-DOF-PID在油管变频加热系统中的应用

为了解决高凝油开采过程中产生的堵井问题,设计了一种针对高凝油开采用的油管变频加热系统.该系统以油管为加热载体,利用油管自身产生的热量对管中高凝油直接加热,达到降凝化蜡的目的.系统采用模糊二自由度PID方法对温度进行智能分时控制,采用移项PWM技术进行调功,选择C8051F310单片机作为系统主控芯片,设计了硬件电路,进行了MATLAB仿真.仿真结果和现场实测曲线均证明了此方法的可行性.该系统有效地解决了电网扰动。

基于闭环耦合度的大系统常规PID控制回路的投用规则

化工过程全流程为具有高维输入输出的多变量大系统,内部存在一定程度的耦合作用,因此其底层常规PID控制系统的设计、投用和整定也必然与整个系统的耦合程度有关。首先,提出了闭环相对增益和耦合度的概念,分析闭环相对增益在理想控制条件下与开环相对增益的等效性,发现闭环控制回路的反馈作用引起操纵变量和被控变量的关联,由此加剧整个系统的耦合程度,因此闭环控制回路并非投用得越多越好。然后,提出了基于闭环耦合度的化工过程大系统常规PID控制回路的投用规则,根据被控过程开环相对增益阵确定控制回路变量配对和投用顺序,依次投用各控制回路并计算控制回路的耦合度,当耦合度超过阈值时停止剩余控制回路的投用。最后,以典型多变量TE过程为例验证了该投用规则的有效性。

7自由度半主动悬架整车模型PID-LQR控制研究

建立七自由度模型,PID控制理论和LQR控制理论相互结合,设计了PID-LQR控制器,对车身垂直加速度、悬架动行程、轮胎动位移、俯仰角加速度和侧倾角加速度进行优化控制.利用MATLAB/Simulink搭建了仿真模型,利用遗传算法优化各项性能指标权重,使用PID参数整定工具箱PID Tuner整定PID参数.为了突出PID-LQR控制的效果,加入被动悬架和采用LQR控制的半主动悬架进行对比,仿真结果表明,采用PID-LQR控制后,相比于被动悬架和采用LQR控制后的半主动悬架,PID-LQR控制方法控制效果显著,各项性能指标有不同程度优化.

基于2-DOF PID控制器的PWM DC/DC变换器的仿真

在PWM DC/DC变换器中,为了提高系统的目标值跟踪特性和干扰抑制特性,通常采用PID调节器.由于这种方式为单自由度控制,所以它的目标值跟踪特性最佳和干扰抑制特性最佳不可兼得.提出了2-DOF PID控制的PWM DC/DC变换器控制模型,并进行了仿真.结果表明了方案的正确性.

Study on 6-DOF active vibration-isolation system of the ultra-precision turning lathe based on GA-BP-PID control for dynamic loads

The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.

模糊免疫2DOF PID在刨花板流量控制系统中的研究与仿真

分析了常规PID和二自由度(degree-of-freedom,以下简称2DOF)PID的优缺点,针对其缺点,基于免疫反馈原理,使2DOF PID部分参数实现自整定。通过与2DOF PID方法在刨花板施胶流量控制系统中的仿真对比,验证了该方法可使系统具有更强的鲁棒性,其更适用于复杂工况。

Synchronous tracking control of 6-DOF hydraulic parallel manipulator using cascade control method

The synchronous tracking control problem of a hydraulic parallel manipulator with six degrees of freedom (DOF) is complicated since the inclusion of hydraulic elements increases the order of the system.To solve this problem,cascade control method with an inner/outer-loop control structure is used,which masks the hydraulic dynamics with the inner-loop so that the designed controller takes into account of both the mechanical dynamics and the hydraulic dynamics of the manipulator.Furthermore,a cross-coupling control approach is introduced to the synchronous tracking control of the manipulator.The position synchronization error is developed by considering motion synchronization between each actuator joint and its adjacent ones based on the synchronous goal.Then,with the feedback of both position error and synchronization error,the tracking is proven to guarantee that both the position errors and synchronization errors asymptotically converge to zero.Moreover,the effectiveness of the proposed approach is verified by the experimental results performed with a 6-DOF hydraulic parallel manipulator.

Long-Term Effect of TMD on Vibration Control of An MDOF Offshore Fixed Platform

A three-dimensional fixed offshore platform in deep water modeled by the finite element method is studied in this paper. Analysis of the dynamic response of the MDOF structure is realized taking the non-linearity of the wave drag force and the wave-structure interaction into account. The structural response statistics, which have Gaussian distributions, are used to evaluate the vibration effect of the structure without TMD and with TMD. And an optimal method to design TMD controlling the first mode of the multi-mode structure is proposed. Moreover, the probabilities of occurrence of sea states at the platform site are considered for prediction of the long-term effect of a TMD. Simulation results demonstrate that the long-term effect of a well-designed TMD is good and the practical use is possible due to the good stability of its optimal parameters under different sea states.

基于萤火虫算法的DDE-PID加热炉炉温控制

针对加热炉炉温控制的目标多变、干扰因素多等问题,提出基于萤火虫算法(firefly algorithm)优化预期动态(desired dynamic equation,DDE)二自由度PID控制策略。将非线性鲁棒控制器(Tornambe Controller)中的不确定因素和外部干扰项利用观测器近似替换,运用预期动态法构建动态特性方程,推导出带有预期动态特性方程系数和观测器参数的二自由度PID等价形式。在判定系统稳定性后确定待优化参数选值范围,进而通过萤火虫优化算法选取最优参数。研究结果表明:与常规PID和二自由度PID控制相比,模型适配时所提出的控制策略使调节时间最多减少38 s,超调量最多降低15%,系统抗干扰性良好。使用所提策略后,炉温控制偏差小于±20℃,炉温波动降低60%,系统稳定性和抗干扰能力明显提高。

双自由度PID-Ⅲ型锁相环在新能源系统的应用

针对电网故障(电压跌落、频率跳变、谐波、其他扰动等)对锁相环相位检测快速性和准确性产生很大影响的问题,文章提出一种基于双自由度PID补偿的快速准确跟踪配电网电压相位信息的锁相环技术,并结合Ⅲ型系统内模特性,给出了双自由度PID补偿器5个参数的设计方法,最后运用MATLAB/Simulink与两种传统的锁相环技术进行仿真对比。结果表明,文章所提锁相环技术能够抑制谐波、直流分量和不对称分量对锁频环的影响,利用PID微分补偿环节显著提高了响应速度,同时实现无静差跟踪加速度信号。