基于模糊PID的粘度仪恒温系统实现

恒温控制系统是粘度仪最重要的部分之一,粘度对于温度变化较为敏感,温度精度要求严格.传统的PID控制技术在温控系统应用广泛,难以达到高精度要求,对于参数比较敏感,为此本文引入模糊控制理论,设计一个PID控制与模糊控制结合的智能温度控制器,利用AVR单片机的PWM波形输出实现恒温控制.当温度误差较大时,采用积分分离PD控制,实现快速升温;当温度误差进入设定的误差阀值内,采用模糊PID控制算法稳态控制,减小超调量.实践证明该控制方法,具有响应快、超调量小、稳定性较好等特点,优于传统控制方法.     

变速积分PID在AUV航向姿态控制中的应用

AVU在航行过程中容易受慢变干扰,传统PID通过加大积分项来抑制干扰,但易引起超调.积分分离PID可以抑制干扰和减小超调,但当慢变干扰大于积分分离的门限时,退化为PD控制器.对此,将变速积分PID引入AUV的航向控制中.在航向运动线性模型基础上设计了控制器,并利用劳斯判据证明了系统稳定性,在典型干扰下进行了仿真验证.结果表明,变速积分PID相对于传统的PID和积分分离PID有更好的性能.     

双重积分器的二阶线性自抗扰控制:快速无超调阶跃响应

双重积分器不易控制, PD和PID控制都难以实现其快速无超调阶跃响应. 本文发现单参数二阶线性自抗扰 控制能实现双重积分器的快速无超调阶跃响应. 同时能任意配置回路传递函数的增益穿越频率, 而保持相位裕度恒 为31.9?. 这是线性自抗扰控制优于PD和PID控制的一个例子. 分析和算例还表明, 在抗低频外扰和高频内扰方面, 二阶线性自抗扰控制优于PD和PID控制.     

基于自适应的大气相干长度测量仪控制系统设计

通过跟踪移动信标来测量大气湍流参数时,高精度的伺服控制技术是影响其测量精度的主要因素之一;在常规PID 控制的基础上,从自适应的角度出发,设计了一种适用于相干长度测量仪的且参数可自整定的控制器;当系统受扰动作用或系统运行状态变化时,在对系统不断辨识的基础上,依据性能指标,配置期望极点,实时调整控制器的参数值,实现系统的自适应,改善系统的鲁棒性;仿真及实验结果表明,采用自适应PID控制,在常值干扰下,系统的超调量减少26%,调节时间缩短1.28 s;跟踪20 mrad/s的目标时,系统的脱靶量峰峰值减小41.78%,稳态误差减小29.3%。相较于常规PID控制器,自适应PID控制器可减小超调量,缩短调节时间,优化跟踪性能,控制效果更好。     

基于Smith模糊PID控制的温室监控系统设计

针对温室控制系统被控对象模型的时变性、时滞性和易受干扰的问题,设计了一种基于Smith模糊PID控制的温室监控系统;该系统以MSP430F5438A单片机为核心,以PC机为远程监控终端实现了对温室温湿度的实时监测与控制;仿真结果表明:Smith模糊PID控制器具有调节时间快、超调量小、抗干扰能力强、鲁棒性好的优点;该系统与常规PID控制相比,超调量减小了11％,调节时间减小了23％,模型参数改为T=400,τ=130后,比Smith-PID控制超调量减小了15％,调节时间减小了30％.实验测试说明该系统控制精度高、稳定性好,具有很大的实用价值.     

Simth纯滞后补偿控制器的设计与仿真

由于过程控制系统的纯滞后特性,采用常规PID控制器会产生明显的超调和较大的调节时间;引入Smith预估器后,闭环系统的单位阶跃响应曲线快速、无超调,解决了纯滞后环节影响闭环系统稳定性的问题。     

坦克稳定器滑动模态变结构控制

该文介绍了用滑动模态变结构控制对坦克水平向稳定器进行设计。滑动模态变结构控制主要由两部分组成：求取切换函数及变结构控制。文章采用最优化方法设计切换函数，保证滑动模态稳定；用幂次趋近律确定变结构控制，使切换面以外的相轨线于有限时间到达切换面。在此基础上又进行了仿真实验。仿真结果显示系统单位阶跃响应快速无超调，稳态误差为零，斜坡输入下能平稳跟踪。该设计方法优于传统设计方法，满足各项技术指标要求，能够有效提高坦克稳定器性能，为稳定器设计提供了一种切实可行的方法。     

带钢卷取机跑偏电液伺服系统PID控制器的设计

针对带钢连续轧制过程中的带钢跑偏问题,文章提出了一种带钢卷取机跑偏电液伺服系统PID控制器的设计方案。在介绍带钢卷取机跑偏电液伺服系统的基础上,通过静态计算,建立了该系统的数学模型;根据带钢卷取机跑偏电液伺服系统的开环传递函数及不同的控制量组合,分别设计了比例控制器、比例积分控制器和比例微分控制器,并采用Matlab软件仿真并分析了各控制器作用下系统的阶跃响应性能,根据各时域响应指标评定并确定了PID控制器的参数值。由PID控制器作用下系统的阶跃响应波形及系统开、闭环波德图得出,该PID控制器超调小、调节时间短、响应快、性能稳定;对带钢卷取机跑偏电液伺服系统的稳态误差进行分析后得出,该系统的稳态误差为零,由此证明了该PID控制器的有效性和正确性。     

双加热探空仪湿度传感器的加热控制研究

利用双加热探空仪电容湿度传感器加热前后相对湿度和温度、露点、饱和水汽压间的关系,分析和建立了去除加热器影响的实际相对湿度的计算方法。采用模糊RBF神经网络PID控制方法对加热器进行控制,从而避免了繁琐的依靠人工实验整定PID参数的过程。Matlab仿真结果表明:同采用Niegler-Nichols经验公式的传统PID控制器相比,模糊RBFPID控制器具有更好的稳定性和更快的响应速度,其阶跃响应超调分别为15.1%,4.3%,允许误差为2%的调节时间分别为7.12,3.8 s。     

电视导引头伺服系统模糊PID控制技术研究

为了满足电视导引头位置伺服系统在部件级测试中的要求,在构成位置闭环的基础上设计了模糊PID控制器以操纵执行机构.控制算法根据位置偏差及变化率将响应划分阶段,经试验确定模糊规则,使用模糊推理实时整定各阶段PID参数,使指标趋于最优.仿真及试验结果表明,模糊PID控制器减小了稳态误差,缩短了调节时间和超调量.模糊PID控制...     

Modelling and motion control of a mechatronic system using BGM with intelligent controllers

In this research paper, a mechatronics system such as a pan tilt platform (PTP) has been considered for motion control under intelligent controllers. A proportional-derivative (PD) controller is considered for comparison of results obtained from fuzzy and hybrid controllers. The trajectory following performance of the mechatronics system is found against these controllers. The results of simulations show that hybrid fuzzy controller reduce the tracking error effectively in lesser settling time. The intelligent controllers require knowledge base of error and derivative of error to compensate the PTP dynamics. The intelligent controllers have similar trends as the PD controllers and compensated both electrical and mechanical dynamics. The PD controller requires position measurement. The intelligent controllers have knowledge base consisting of position and velocity data. Thus intelligent controllers have position measurement along with knowledge base for position control system. The best results were achieved with hybrid fuzzy controllers. They meet the desired specifications.     

随机激励下板球系统建模与有限时间全状态预设性能跟踪控制

研究板球系统受到随机激励时的数学建模与轨迹跟踪控制问题. 首次建立了板球系统的随机数学模型, 并 结合backstepping方法、有限时间预设性能函数、全状态约束及新的预设性能推导方法设计了具有未知输入饱和的 随机板球系统实际有限时间全状态预设性能跟踪控制器, 实现了随机激励下板球系统的有限时间预设性能轨迹跟 踪控制. 所设计的控制器保证了系统跟踪误差能够被预先给定的有限时间性能函数约束, 并且能在任意给定的停息 时间内收敛到预先给定的邻域内. 最后通过仿真实验验证了所设计控制器具有更好的控制效果.     

Multivariable integral linear quadratic Gaussian robust control of islanded microgrid to mitigate voltage oscillation for improving transient response

A novel robust integral linear quadratic Gaussian (ILQG) controller is presented in this paper to control the voltage of islanded microgrid and improves its transient response. Microgrid is a small grid that consists of number of distributed generator units, power‐electronic components with inductor‐capacitor (LC) filters and loads. The loads are parametrically uncertain and unknown that produces the voltage or power oscillation. The ILQG controller is capable to compensate for the voltage oscillation and exhibits the tracking of grid voltage against the different load dynamics. The design of ILQG controller is carried out by augmenting the plant dynamics with an integrator. The robustness of the ILQG controller is studied by considering a number of uncertainties within the plant model. The performance of ILQG controller is compared with linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controller in terms of rise time, settling time, bandwidth and tracking error. The comparison results ensure the high bandwidth and tracking performance of ILQG controller as compared to other controllers.     

运动控制中的鲁棒自适应死区补偿

在高精度PD控制器中,死区可能会产生极限环,而且,死区参数往往未知.本文针对有非对称死区的直流伺服系统,设计了一种鲁棒自适应预补偿控制器,这种控制器不仅对死区的不确定性具有鲁棒性,而且对惯性及粘性摩擦等参数的不确定性,及外部扰动都有较强的鲁棒性.采用Lyapunov理论证明了这种控制器能够保证跟踪误差一致最终有界.并且调整调节控制器的参数可以改变跟踪误差.仿真结果表明了这种方法的有效性.     

A distributed leader‐following tracking controller using delayed control input information from neighbors

In this paper, we propose a simple, continuous, and distributed controller for the second‐order multiagent system to achieve leader‐following trajectory tracking, by exploiting the control input information of neighbors (CIIN) and using proportional‐derivative (PD) control in terms of local neighborhood synchronization error. A constant time delay is introduced in the CIIN as a design parameter to avoid the algebraic loop issue arising from the control input coupling. We develop an easily testable condition on the PD gains to ensure that the resulting neutral‐type error system is input‐to‐state stable for an arbitrary bounded delay, and prove that when the leader's acceleration is a Lipschitz continuous function with respect to time, the ultimate bound of tracking errors is strictly increasing with respect to the introduced time delay. Moreover, we analyze the robustness of the controller with respect to model uncertainties and show its potential advantages over two existing controllers in balancing the steady‐state tracking precision, the communication cost, and the continuity of controller signal. Finally, extensive simulations are conducted to show the effect of the delay on system stability, to verify the condition on PD gains, to confirm the robustness of the controller, and to demonstrate the detailed advantages.     

Further results on adaptive iterative learning control of robot manipulators

Based on a combination of a PD controller and a switching type two-parameter compensation force, an iterative learning controller with a projection-free adaptive algorithm is presented in this paper for repetitive control of uncertain robot manipulators. The adaptive iterative learning controller is designed without any a priori knowledge of robot parameters under certain properties on the dynamics of robot manipulators with revolute joints only. This new adaptive algorithm uses a combined time-domain and iteration-domain adaptation law allowing to guarantee the boundedness of the tracking error and the control input, in the sense of the infinity norm, as well as the convergence of the tracking error to zero, without any a priori knowledge of robot parameters. Simulation results are provided to illustrate the effectiveness of the learning controller.     

Fixed‐time attitude tracking control for spacecraft based on adding power integrator technique

In this article, the fixed‐time attitude tracking problem for rigid spacecraft is investigated based on the adding‐a‐power‐integrator control technique. First, a fixed‐time attitude tracking controller is designed to guarantee fixed‐time convergence of tracking errors. Then, by considering the presence of random disturbance and actuator faults, an adaptive fault‐tolerant attitude tracking controller is designed to guarantee tracking errors converge to a residual set of zero in a fixed time. The complete bounds on settling time are derived independently of initial conditions. The simulation results illustrate the highly precise and robust attitude control performance obtained by using the proposed controllers.     

Predefined-time control for Euler–Lagrange systems with model uncertainties and actuator faults

A novel adaptive predefined-time tracking control algorithm is proposed for the Euler–Lagrange systems (ELSs) with model uncertainties and actuator faults. Compared with traditional finite-time and fixed-time studies, the system output tracking error under the proposed predefined-time controller converges to a small neighborhood of zero in finite time, whose upper bound is exactly a design parameter in the control algorithm. For the uncertain model, radial-based function neural network (RBFNN) is utilized to approximate the continuous uncertain dynamics. To deal with the actuator faults, an adaptive control law is involved in the fault-tolerant controller. In order to achieve the predefined-time bounded, a novel predefined-time sliding mode surface is designed. It is proved that the tracking error vector trajectory of closed-loop system is semi-globally uniformly ultimately predefined-time bounded, and the upper bounds of both the system settling time and the corresponding output tracking error can be adjusted with a simple parameter. Simulation examples finally demonstrate the effectiveness of the proposed control algorithm.     

Prespecifiable fixed‐time control for a class of uncertain nonlinear systems in strict‐feedback form

In this paper, we investigate the prespecifiable fixed‐time control problem for a class of uncertain nonlinear systems in strict‐feedback form, where the settling (convergence) time is not only bounded but also user‐assignable in advance. One of the salient features of the proposed method lies in the fact that it makes it possible to achieve any practically allowable settling time by using a simple and effective control parameter selection recipe. Both fixed‐time stabilization and fixed‐time tracking are considered for uncertain strict‐feedback systems. Firstly, by adding exponential state feedback and using fractional power integration as Lyapunov function candidate, a global stabilizing control strategy is developed. It is proved that all the system states converge to zero within prespecified fixed‐time with continuous and bounded control action. Secondly, under more general uncertain nonlinearities and external disturbances, an adaptive fixed‐time controller is derived such that the tracking error converges to a small neighborhood of zero within preassigned time. Theoretical results are also illustrated and supported by simulation studies.     

Event-triggered adaptive tracking control for nonlinear systems with input saturation and unknown control directions

This article is concerned with event-triggered adaptive tracking control design of strict-feedback nonlinear systems, which are subject to input saturation and unknown control directions. In the design procedure, a smooth nonlinear function is employed to approximate the saturation function so that the controller can be designed under the framework of backstepping. The Nussbaum gain technique is employed to address the issue of the unknown control directions. A predetermined time convergent performance function and a nonlinear mapping technique are introduced to guarantee that the tracking error can converge in the predetermined time with a fast convergence rate and a high accuracy. Then the event-triggered adaptive prescribed performance tracking control strategy is proposed, which not only ensures the boundedness of all the closed-loop signals and the convergence of tracking error but also reduces the communication burden from the controller to the actuator. At last, the simulation study further tests the availability of the proposed control strategy.