Modeling and fuzzy adaptive proportion-integration-differentiation control of X-Y position servo system actuated by oscillating pneumatic cylinder

The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinear control system. Its mathematical model is established, and nonlinear factors are analyzed. Due to the existence of deadlock zone and the small damp of the pneumatic oscillating cylinder, it is likely to result in overshoot, and there is also certain steady-state error, so online modifying of proportion-integration-differentiation （PID） parameters is needed so as to achieve better control performance. Meanwhile considering the stability demand for long-term run, a fuzzy adaptive PID controller is designed. The result of hardware-inloop （HIL） test and real-time control experiment shows that the adaptive PID controller has desirable serfadaptability and robustness to external disturbance and to change of system parameters, and its control per- fonnance is better than that of traditional PID controllers.

Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system,adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty.At the same time,gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort.The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome.On the other hand,the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy,and the chattering phenomenon of the control effort is also suppressed effectively.

Adaptive predictive functional control based on Takagi-Sugeno model and its application to pH process

In order to obtain accurate prediction model and compensate for the influence of model mismatch on the control performance of the system and avoid solving nonlinear programming problem,an adaptive fuzzy predictive functional control(AFPFC) scheme for multivariable nonlinear systems was proposed.Firstly,multivariable nonlinear systems were described based on Takagi-Sugeno(T-S) fuzzy models;assuming that the antecedent parameters of T-S models were kept,the consequent parameters were identified on-line by using the weighted recursive least square(WRLS) method.Secondly,the identified T-S models were linearized to be time-varying state space model at each sampling instant.Finally,by using linear predictive control technique the analysis solution of the optimal control law of AFPFC was established.The application results for pH neutralization process show that the absolute error between the identified T-S model output and the process output is smaller than 0.015;the tracking ability of the proposed AFPFC is superior to that of non-AFPFC(NAFPFC) for pH process without disturbances,the overshoot of the effluent pH value of AFPFC with disturbances is decreased by 50% compared with that of NAFPFC;when the process parameters of AFPFC vary with time the integrated absolute error(IAE) performance index still retains to be less than 200 compared with that of NAFPFC.

Hybrid Adaptive Compensation Control Scheme for High-Precision Servo System

In this paper,a hybrid adaptive compensation control scheme is proposed to compensate the friction occurrence and other nonlinear disturbance factors that exist in the high-precision servo system.An adaptive compensation controller with a dual-observer structure is designed,while the LuGre dynamic friction model with non-uniform parametric uncertainties characterizes the friction torque.Considering the influence of the periodic disturbance torque and parametric uncertainties,fuzzy systems and a robust term are employed.In this way,the whole system can be treated as a simple linear model after being compensated,then the proportional-derivative (PD) control law is applied to enhancing the control performance.On the basis of Lyapunov stability theory,the global stability and the asymptotic convergence of the tracking error are proved.Numerical simulations demonstrate that the proposed scheme has potentials to restrain the impact of disturbance and improving the tracking performance.

Adaptive Fuzzy Torque Control of Passive Torque Servo Systems Based on Small Gain Theorem and Input-to-state Stability

Passive torque servo system （PTSS） simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturbance is called extra torque. The most important issue for PTSS controller design is how to eliminate the influence of extra torque. Using backstepping technique, adaptive fuzzy torque control （AFTC） algorithm is proposed for PTSS in this paper, which reflects the essential characteristics of PTSS and guarantees transient tracking performance as well as final tracking accuracy. Takagi-Sugeno （T-S） fuzzy logic system is utilized to compensate parametric uncertainties and unstructured uncertainties. The output velocity of actuator identified model is introduced into AFTC aiming to eliminate extra torque. The closed-loop stability is studied using small gain theorem and the control system is proved to be semiglobally uniformly ultimately bounded. The proposed AFTC algorithm is applied to an electric load simulator （ELS）, and the comparative experimental results indicate that AFTC controller is effective for PTSS.

Bang-Bang+Fuzzy-PI自适应控制器的应用研究

针对电液伺服系统模型不精确、参数时变和负载干扰大的特点,提出了一种Bang-Bang+Fuzzy-PI的自适应复合控制器,利用模糊开关在不同控制方式间切换,并采用遗传算法对Fuzzy控制器的量化因子和PI控制器的积分系数进行在线优化。比较了复合控制器与Fuzzy控制器、Fuzzy-PI控制器和PID控制器的主要动态及静态指标,仿真结果表明这种复合控制器上升时间短、稳态精度高、鲁棒性强,具有优良的控制性能。

电液振动台自适应Fuzzy-PI控制器的设计

在离心加速度和振动复合环境中，用于结构振动试验的电液伺服控制系统是一个时变耦合的非确定性系统。本文考虑了上述因素，提出了自适应Ｆｕｚｚｙ－ＰＩ控制方法。控制参数可由自适应Ｆｕｚｚｙ－ＰＩ构件进行动态调整。采用模糊法则及ＣＲＩ推理确定参数。本文介绍了控制器的设计方法，并给出了正弦振动加载试验的结果。结果表明控制器有较高的稳态精度，动态特性好，自适应能力强。

基于大数据的水肥一体机控制应用研究

针对传统灌溉方式水资源利用率低、农业用水浪费严重、肥料过度使用造成资源浪费和水污染等问题,基于大数据对水肥一体机的控制进行了设计。为了保证水肥一体机的灌溉精准性以及获取数据的精确性,采用自适用加权融合算法对获取的数据进行处理;为了对水肥浓度进行智能控制,采用PID控制器和自适应模糊控制器结合的方式对肥液浓度进行控制;为了验证该水肥一体机的性能,对其进行了浓度试验和肥料配比控制试验。结果表明:肥液浓度可以通过电导率仪进行测量,且设计控制器对肥液浓度的控制效果更优。

模糊自适应PID对保险粉合成pH值的控制研究

保险粉合成过程pH值控制存在非线性、时滞性、不确定性问题,采用常规PID控制结合人工控制的方式无法实现参数自调整,对pH值的控制很难达到预期效果,为此,提出了模糊自适应PID控制方法。介绍了保险粉合成原理及反应方程式,分析酸碱中和pH值控制并确定系统的传递函数,设计了模糊自适应PID控制器,通过Matlab/Simulink进行仿真分析,并进行了实验验证,结果表明:模糊自适应PID控制与常规PID控制相比,具有超调量小、调节时间短、抗干扰能力强等优点,实现了对pH值的有效控制。

Application of Fuzzy Modification Strategy in MRAC

Based on a simplified model reference adaptive control(SMRAC) algorithm a parameter modification algorithm according to fuzzy laws is proposed in this paper. The method makes the adaptive parameters in SMRAC only rely on the status of performance error. Thus it eliminates the influences of gain coefficients in SMRAC and the amplitude of input signal on the dynamic characteristics. Experiments on various step amplitudes and loads show that the performances of SMRAC are improved by incorporating fuzzy modification method.

基于自适应模糊控制的汽车焊接过程方法研究

针对当前汽车车身焊接费时费力、焊点不连续、表面质量差等问题,提出一种基于自适应模糊控制的焊接过程算法。通过构建工业机器人、C型短式伺服焊钳及旋转式双面夹具台的运动模型,利用模糊规则制定PID控制参数,有效提高了伺服控制系统的跟踪精度及动态响应能力。试验结果表明,该方法能较好地解决车身连续焊接过程生产的问题。

电石炉电极电流智能切换控制系统

当原料、炉况和加料过程发生未知变化时,电石炉电极控制系统的特性发生变化,导致PI控制系统难以满足电石炉的控制目标。将电石炉的动态特性与模糊自适应PI控制、规则切换控制相结合,提出了电石炉电极控制系统智能切换控制方法。设计了可编程逻辑控制器(programmable logic controller,PLC)系统软硬件平台,开发了基于所提控制方法的应用软件并研发了电石炉电极电流控制系统,成功应用于神木电化发展有限公司电石分厂。长期运行结果表明,采用所研制的电石炉电极电流控制系统,实现了生产过程的安全稳定运行,可以将电石炉电极电流控制在工艺规定的目标值范围内,提高了产品质量,降低了生产能耗,提高了企业的经济效益。

基于模糊PID的变幅液压缸伺服位置自适应同步控制技术

液压系统中存在许多非线性因素,例如摩擦、死区和溢流等。这些非线性特性会影响伺服位置的精度和同步性能,导致控制系统的不稳定和误差积累。为此,提出基于模糊PID的变幅液压缸伺服位置自适应同步控制技术。考虑变幅液压缸伺服系统的运行结构,分析变幅液压缸动力,构建液压缸以及伺服阀的数学模型;利用伺服输出流量和压降的关系,获取速度前馈控制信号;将其反馈到系统中,设计模糊自适应PID同步控制器,实现变幅液压缸伺服位置同步控制。实验结果表明,所提方法对液压缸的同步效果很好,有效减少了液压缸伺服位置控制的误差,在不同信号干扰下,有效提高其控制稳定性和同步性能,控制器超调量平均约为0.059%,响应速度较快。

Some Investigations on Fuzzy P+Fuzzy I+Fuzzy D Controller for Non-stationary Process

The paper addresses the adaptive behaviour of parallel fuzzy proportional plus fuzzy integral plus fuzzy derivative (FP+FI+FD) controller. The parallel FP+FI+FD controller is actually a non-linear adaptive controller whose gain changes continuously with output of the process under control. Two non-stationary processes, whose characteristics change with time, are considered for simulation study. Simulation is performed using software LabVIEW TM . The set-point tracking response of parallel FP+FI+FD is compared with conventional parallel proportional plus integral plus derivative (PID) controller, tuned with the Ziegler-Nichols (Z-N) tuning technique. Simulation results show that conventional PID controller fails to track the set-point and becomes unstable as the process changes its characteristic with time. But the parallel FP+FI+FD controller shows considerably much better set-point tracking response and does not deviate from steady state. Also, a huge spike is observed in the output of PID controller as the reference set-point and process parameters are changed, while the FP+FI+FD controller gives spike free control signal.

超大型环件径轴向轧制过程偏移机理及自适应模糊控制方法研究

超大型环件径轴向轧制过程容易产生偏移,影响环件轧制稳定性和成形质量。为研究环件偏移机理及其控制方法,分析了轴向孔型滑移区中前滑区和后滑区的分布变化规律,建立了理想情况下不产生环件偏移时锥辊旋转运动学条件,获得了滑移区的最优速度匹配系数。此外,从历史轧制数据中归纳人工控制经验后提出了基于锥辊转速自适应模糊调节的环心偏移量控制方法,基于ABAQUS软件和VUAMP子程序开发,建立了集成有环心偏移量模糊控制算法的∅10 m超大型环件径轴向轧制有限元模型,研究了采用最优速度匹配系数的常规控制和自适应模糊控制下的环心偏移量变化规律。结果表明,自适应模糊控制下的平均环心偏移量相比于常规控制降低了72.4%,仿真结果和试验数据均验证了所提超大型环件轧制过程偏移自适应模糊控制方法的有效性。

基于自适应模糊滑模控制在交流伺服系统中的应用

在伺服电动机控制系统的使用中,由于电动机存在端部效应引起的动子磁链非正弦性、摩擦非线性以及负载的变化等都将使高精度位置伺服系统性能变坏,因此必须采用鲁棒性强的控制策略来抑制这些扰动。本文设计了一种带积分滑模面的自适应模糊滑模控制系统,并将其应用于伺服电动机的位置控制系统中。自适应模糊滑模控制系统由模糊控制和切换控制组成,运用模糊控制器来模拟反馈线性化控制率,使用切换控制来补偿滑模控制器的输出误差。调节算法是从李雅普洛夫稳定性理论得到的,从而可以保证系统的稳定性。经仿真验证,所设计的系统性能令人满意,而且对参数变化和外部负载扰动具有较强的鲁棒性。

污水处理过程多变量自适应变论域模糊控制

由于污水处理过程具有非线性、时变性和滞后性的特点,传统控制方法难以取得满意的控制效果。为了实现精确跟踪控制,提出了一种基于自适应变论域模糊控制(adaptive variable universe fuzzy control,AVUFC)的污水处理过程多变量控制方法,实现了溶解氧和硝态氮的底层回路控制。在AVUFC中,根据性能指标设计了基于自适应差分进化算法的伸缩因子调整策略,在线自适应调节模糊控制论域,降低工况变化对控制器性能的影响,提高控制器的动态性能和稳态精度。利用国际基准仿真平台BSM1进行实验验证。仿真结果表明,当入水流量和组分浓度发生剧烈变化时,所提出的自适应变论域模糊控制策略能够通过在线优化模糊规则以快速适应复杂工况;与PID控制、模糊逻辑控制、定式变论域模糊控制等方法相比,自适应变论域模糊控制在平稳性、抗干扰性和瞬态响应能力方面更具优势。

齿轮加工机床用永磁同步电机直接转矩控制方法

针对齿轮加工机床的高精度伺服控制需求,改进永磁同步电机并提出一种自动化的直接转矩控制方法。根据齿轮加工机床传动装置特点与通用型永磁同步电机结构,将呈圆周分布的定子改为直线分布形式,用初级部件、次级部件代替定子、转子。依据永磁同步直线电机结构与子系统的分析情况,通过转矩估计、磁链估计和模糊自适应控制等阶段,实现直接转矩控制的自动化控制。选取七轴五联动数控弧齿锥齿轮磨齿机作为实验对象,设置电机与所提方法的相关技术参数后,检验永磁同步直线电机性能与直接转矩控制性能。实验结果表明,经所提方法控制后的电机稳定性与散热性良好,证明所提方法对电机负载状态具有较好的自适应性,自动控制效果较为理想。

考虑齿隙伺服系统的反步自适应模糊控制

针对具有未知参数和齿隙非线性的机电伺服系统,引入一种近似死区函数建立了系统的数学模型,给出了死区函数中参数的选取方法.用两个自适应模糊逻辑系统在线逼近机电伺服系统中的未知参数和非线性环节,从而避免了对每个未知参数推导自适应律.基于反步法设计了自适应模糊控制器,可抑制未知参数和齿隙非线性对系统性能的影响.采用Lyapunov方法证明了位置跟踪误差的指数收敛性.与PID控制方法对比的仿真实验表明,本文方法能够显著减小齿轮间传递力矩的振荡,并具有很好的控制精度和鲁棒性.

用于气动伺服系统的自适应神经模糊控制器

研究了一种基于压力比例阀的气动伺服系统自适应神经模糊控制器。其中的神经网络辨识器（NNI）通过离线训练可以充分逼近非线性动态系统的模型，并能够在线调整模糊控制器的控制规则。系统的位置控制精度和伺服特性有了很大改善。试验结果表明，所提出的控制器对该气动伺服系统具有很好的控制特性以及很强的自适应能力。