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运用反馈控制理论分析了TCP模型的稳定性能,并设计PID控制器以提高该系统的稳定性,采用OPNET对带PID控制器的TCP拥塞控制系统进行了仿真。仿真结果表明,PID控制器比传统的RED具有更快的响应速度、更小的队列长度波动和更大的链路利用率。 相似文献
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模糊自适应算法在网络主动队列管理中的研究 总被引:3,自引:1,他引:3
为了改善由于RED算法控制的主动队列管理策略(AQM)系统引起网络响应时间过长,许多文献提出了基于P/PI控制器的AQM策略。但是,由于网络具有非线性特点,论文设计了一种模糊自适应PID控制器的主动队列管理系统,根据队列长度和队列长度变化通过模糊控制规则在线调整PID控制器参数,并用Matlab进行了仿真,验证了当网络出现突发分组时,该算法能够较快的使分组稳定在队列阀值附近,同时不产生队列震荡。 相似文献
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主动队列管理(AQM)对于保持TCP网络高性能是一种有效的策略。AQM的基本机制是调节数据包进入路由器缓冲区的速率,从而避免网络拥塞。针对传统PID控制器在拥塞控制过程中参数固定的缺点,将神经网络理论引入AQM的研究中,设计了一种改进的单神经元自适应PID主动队列管理器。基于NS2平台的仿真结果表明,与PID控制器及传统的单神经元自适应PID控制器相比,改进的控制器对网络环境的变化有更强的适应能力和更好的稳定性。 相似文献
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模糊PID控制器的稳定性分析 总被引:2,自引:0,他引:2
构造出一种PID型模糊控制器,并证明了这种模糊控制器近似于一种变参数的PID控制器,以PID模型为基础,基于无源性定量对模型PID控制器的稳定性进行分析,导出了使模糊PID控制器稳定的充分条件,为设计稳定的模糊PID控制器提供了理论指导。 相似文献
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应用控制理论对网络数据传输过程进行了分析和建模,提出了一种基于回环时间RTT的P-Smith预估拥塞控制策略.该方法建立在RTT长相关性的基础上,可以在线实时调节控制器中的比例系数和时延参数以保证控制回路的稳定性以及发送速率的平滑性.仿真结果表明,使用该控制方案能使缓冲器队列长度快速收敛到目标值,发送速率具有良好的平滑性能,与传统的PID 控制器相比具有更好的稳定性和鲁棒性. 相似文献
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针对具有非最小相位时滞的过程,基于Smith预估控制思想,提出一种改进控制方案,对右半平面零点和纯滞后同时进行补偿,使闭环特征方程中不含右半平面零点,从而简化控制器设计。根据期望闭环传函,解析得出PID控制器形式,综合负调、响应时间、ISE以及鲁棒性要求整定控制器参数,针对Smith控制抗扰性较差提出了抗扰性设计。仿真结果表明,该方案对于具有非最小相位时滞的对象有较好的控制效果,并且在模型失配和有干扰输入的情况下,有较好的鲁棒性和抗扰性。 相似文献
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Eric Hoi-Kwun Fung Yiu-Kwong Wong Yan Ma Chun-Wah Marcus Yuen Wai-Keung Wong 《International Journal of Control, Automation and Systems》2011,9(4):691-700
The controlled smart hanger is an indispensable component in the automatic system for garment inspection. Fuzzy logic is chosen
for the smart hanger manipulator since it can describe the human behavior remarkably well. In this paper, the dynamic model
of the manipulator governing the contact force with garment fabric is first developed. An adaptive fuzzy logic PID control
scheme is successfully formulated for the contact force control. Simulation results indicate that the fuzzy PID controller
can yield a faster response without overshoot and a smaller error performance as compared to the traditional method based
on PID. The stability of the fuzzy PID controller is also demonstrated by computer simulations. 相似文献
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为了实现水压加载系统能够动态精确跟踪给定压力的要求,利用小脑模型关节控制器(CMAC)结构简单、收敛速度快、具有局部学习能力的特点,提出了一种除了系统动态误差以外把系统指令信号也作为CMAC的输入信号,并把CMAC控制器与常规PID控制器并联构成的复合控制方法;通过在MATLAB中的编程仿真试验,结果表明这种方法可以得到比常规PID控制更好的控制指标,达到了试验要求,而且具有良好的抗干扰能力,从而证明了该方法的可行性和有效性,可以用来实现对给定信号的跟踪。 相似文献
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In this paper, an adaptive control scheme is employed for joining Aluminium 6061 alloy sheets by Cold Metal Transfer (CMT) process. The transfer function model of the CMT welding system is derived using empirical equations. The CMT plant transfer function is estimated using system identification technique. For the estimated plant model, a conventional PID controller is initially designed by tuning the controller parameters. The designed control system is tested for its ability to control the welding current when short circuit phase and arcing phase are detected. Following the conventional PID controller, a Model Reference Adaptive Controller is implemented to maintain the welding current at desired range during melting and electrode wire short circuiting. The performance analysis for the proposed adaptive control scheme and the conventional PID controller is compared. The simulation results indicate that the conventional PID controller is unable to retrieve the desired current during short circuit phase and arcing phase. Nevertheless, the proposed MRAC for CMT process successfully maintains the welding current at the setpoint when subjected to arcing phases and short circuit respectively, while ensuring arc stability. The experimental validation is carried out in the CMT welding set up using the designed MRAC. The experimental results emphasize that the MRAC improves the welding performance by yielding good weld joints swiftly and enhanced quality besides minimizing the design complexities. 相似文献
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在疏浚工程中抽砂系统一般采用PID控制器调节泥浆浓度,但当河床形态及河水流速等工况变化时,基于固定参数的PID控制难以达到满意效果。针对被控对象的特性,提出将参数模糊自整定PID与模糊前馈结合的控制方案。该方案能根据工况变化动态调节PID参数,并根据龙头吸咀与河底距离提供前馈补偿,能及时抑制吸咀位置对泥浆浓度灵敏度的影响。仿真结果表明,与传统PID控制相比,该方案对不同工况均能表现出较低的超调量,更快的响应速度,以及更强的抗干扰能力和稳定性。 相似文献
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This paper provides a deep insight into the saturated PID control of a double integrator with bounded disturbance. On the basis of the nested saturation functions, a simple PID‐like controller is proposed. The main difficulty in saturation control with bounded disturbances is to prove that the unsaturated regions are invariant. By phase plane and singular perturbation analysis, we prove that the saturation restrictions on the controller can be removed one by one in finite time, and the closed‐loop system can be finally reduced to a nonsaturated PID controlled double integrator. The sufficient conditions for the stability of the closed loop with disturbance are also derived. Finally, numerical simulations are conducted to validate the effectiveness of the proposed control scheme. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献