器件结构中材料应力的控制和优化方法

在对器件结构中材料应力进行分析和测量的基础上，提出了控制和优化器件结构中材料应力的几种方法，包括合理选择工艺条件、采用多层复合膜技术、确定双层结构的最佳厚度值以及选择适当的材料种类等。实际应用结果表明，这些方法是有效的和可行的。     

RBF神经网络在薄膜厚度控制系统中的应用

针对双向拉伸薄膜厚度控制系统中,经典的PID控制器难以达到理想控制效果的问题,设计一个基于RBF神经网络整定的PID控制器。该控制器由RBF网络对系统进行在线辨识,找到最佳控制参数,并将其反馈给PID控制器,从而实现控制器参数的在线调整。仿真结果表明,本控制器具有超调量小,响应速度快和自适应性强等优点,可有效提高双向拉伸薄膜厚度控制系统的性能。     

薄膜卷制过程中张力控制系统的应用

张力控制系统是以卷材为材料的生产机械上的最重要的控制系统。张力的变化对卷材产品质量会产生很大的影响。对张力控制方法、测量结构进行了分析,并对控制系统进行分类比较,并通过在薄膜电容卷绕机中张力控制的应用,提出了新的张力控制方案,最后就张力控制技术的发展做了阐述。     

基于labview的压力反馈和控制系统研究

在labview软件环境下,本文设计了一种压力反馈和控制系统.而该系统能够利用模糊PID控制器实现气缸压力跟踪和反馈,并通过控制气动阀实现气缸压力精确调节,因此能够满足压力反馈和控制要求.     

小型验证飞艇气体压力控制系统设计

介绍了小型验证飞艇中压力控制系统的主要设计方案,尤其是控制系统的核心--控制器的设计方法.针对囊体内的压力控制具有明显的非线性和模型不确定性的特点,在数字PID控制的基础上提出了将智能控制理论应用到飞艇压力控制系统设计中的设计方法,以达到更精确有效的控制.     

航空发动机模糊滑模变结构控制研究

针对航空发动机是一个具有时变不确定性的非线性系统,结合模糊控制和滑模变结构控制的特点,提出了一种基于模糊滑模变结构控制的航空发动机控制方法.采用线性滑模面和指数趋近律设计变结构控制器,应用模糊逻辑系统自适应调节切换增益,避免了传统滑模变结构控制系统在到达阶段对不确定性的敏感性,消除了滑模控制中的抖振.通过数字仿真,结果表明所设计的模糊滑模变结构控制器对系统的参数摄动和外部干扰具有不变性,使被控系统在整个控制阶段都具有较强的鲁棒性.     

一种新型BST薄膜移相器的电路设计

采用铁电材料钛酸锶钡(BST)的薄膜移相器以其成本低廉、响应速度快、频带宽、体积小、重量轻、控制简单等诸多优点而引起关注.本文对BST薄膜移相器的设计模型进行研究分析,提出了一种新型的电路结构,在BST材料移相器的大移相量和尽可能低的损耗一对矛盾中找到一个平衡点.并通过ADS仿真验证了这一新型电路.     

基于TMS320LF2407的材料试验机集成数据采集及控制系统的研制

本文对材料试验机集成数据采集及控制系统进行了研究.提出了设计方案,研制了以TMS320LF2407为核心的硬件集成电路.设计了基于模糊自整定PID控制算法的控制系统软件和用户软件.针对设计的系统软件做了应力速度控制试验,试验结果表明,应力速度控制得到实现,且稳定性好.     

新型单绕组无轴承异步电机控制系统

研究了一种新型结构的单绕组无轴承异步电机,与传统的双绕组无轴承异步电机相比,采用一套绕组即可实现电机转子的悬浮和旋转。在分析单绕组无轴承异步电机新型结构和工作原理的基础上,推导出电机径向悬浮力和转矩部分的数学模型。针对单绕组无轴承异步电机的定子电流连接的复杂性,采用电流叠加控制方法,并设计基于气隙磁场定向控制的控制系统。在MATLAB/Simulink中建立控制系统的仿真模型进行仿真验证,并制作实验样机进行悬浮特性试验。结果表明,该方法控制的样机转速响应好、悬浮特性优良,从而验证了所提方法的正确性与有效性。     

退火处理对ZnO薄膜结晶性能的影响

研究了退火处理对ZnO薄膜结晶性能的影响.ZnO薄膜由直流反应磁控溅射技术制得,并在O2气氛中不同温度(200～1000℃)下退火,利用X射线衍射(XRD)、原子力显微镜(AFM)和X射线光电子能谱(XPS)对其结晶性能进行了研究,提出了一个较为完善的ZnO薄膜退火模型.研究表明:热处理可使c轴生长的薄膜取向性增强;随退火温度的升高,薄膜沿c轴的张应力减小,压应力增加;同时晶粒度增大,表面粗糙度也随之增加.在640℃的应力松弛温度(SRT)下,ZnO薄膜具有很好的c轴取向,沿c轴的应力处于松弛状态,晶粒度不大,表面粗糙度较小,此时ZnO薄膜的结晶性能最优.     

Adaptive enhanced fuzzy sliding-mode control for electrical servo drive

The design and properties of an adaptive enhanced fuzzy sliding-mode control (AEFSMC) system for an indirect field-oriented induction motor (IM) drive to track periodic commands are addressed in this study. A newly designed EFSMC system, in which a translation-width idea is embedded into the FSMC, is introduced initially. Moreover, to confront the uncertainties existed in practical applications, an adaptive tuner, which is derived in the sense of the Lyapunov stability theorem, is utilized to adjust the EFSMC parameter for further assuring robust and optimal control performance. The indirect field-oriented IM drive with the AEFSMC scheme possesses the salient advantages of simple control framework, free from chattering, stable tracking control performance, and robust to uncertainties. In addition, numerical simulation and experimental results due to periodic sinusoidal commands are provided to verify the effectiveness of the proposed control strategy, and its advantages are indicated in comparison with FSMC and EFSMC systems.     

Extended sliding mode observer based robust adaptive backstepping controller for electro-hydraulic servo system: Theory and experiment

This paper firstly presents an extended sliding mode observer (ESMO) for the electro-hydraulic servo systems (EHSSs) to deal with nonlinear factors like the external disturbance, parameter uncertainties as well as unmodeled characteristics in the EHSS. The model for the EHSS is established by taking these nonlinear factors into consideration and then the statespace representation is obtained. According to the state space, the ESMO for the EHSS is presented, the equivalence principle is properly utilized to simplify the ESMO and some saturation functions are employed to eliminate high frequency interferences caused by the chattering phenomenon. Based on estimated values from the ESMO, a robust adaptive backstepping controller (RABC) is presented in detail with taking some parameter uncertainties into consideration to further improve the tracking performance. The proposed controller has the following advantages: (1) utilizing the ESMO to cope with these nonlinear factors; (2) parameter online adaptive laws are employed in the RABC design to further improve the tracking performance. In order to verify the performance of the proposed controller, an experiment bench was established. Two sine waves reference signal (one amplitude 0.01 m, 1 Hz; the other 0.015 m, 2 Hz) are employed to verify the performance of the controller. Comparative experimental results show that: (1) the tracking performance of the proposed controller is better than that of a DOs based BC, a BC and a PI controller; (2) estimation values from the ESMO contains fewer noise than two conventional disturbance observers (DOs), which will decrease the control input ripples.     

Fuzzy neural networks for direct adaptive control

It is well known that sliding-mode control is simple and insensitive to uncertainties and disturbances. However, control input chattering is the main problem of the classical sliding-mode controller (SMC). In this paper, a fuzzy neural network SMC (FNNSMC) is presented for a class of nonlinear systems. The FNNSMC can eliminate the chattering, unlike the SMC, but there is larger rising time in the FNNSMC than in the SMC. In some cases, small rise time is important. To decrease the rising time of the FNNSMC, an adaptive controller is proposed where the SMC and the FNNSMC are incorporated by a smooth transformation. This adaptive control scheme can improve the dynamical performance and eliminate the high-frequency chattering in the control signal. The system stability is proved by using the Lyapunov function. The simulation results demonstrate the advantages of the proposed adaptive controller.     

Adaptive robust control of fully-constrained cable driven parallel robots

In this paper, adaptive robust control (ARC) of fully-constrained cable driven parallel robots is studied in detail. Since kinematic and dynamic models of the robot are partly structurally unknown in practice, in this paper an adaptive robust sliding mode controller is proposed based on the adaptation of the upper bound of the uncertainties. This approach does not require pre-knowledge of the uncertainties upper bounds and linear regression form of kinematic and dynamic models. Moreover, to ensure that all cables remain in tension, proposed control algorithm benefit the internal force concept in its structure. The proposed controller not only keeps all cables under tension for the whole workspace of the robot, it is chattering-free, computationally simple and it does not require measurement of the end-effector acceleration. The stability of the closed-loop system with proposed control algorithm is analyzed through Lyapunov second method and it is shown that the tracking error will remain uniformly ultimately bounded (UUB). Finally, the effectiveness of the proposed control algorithm is examined through some experiments on a planar cable driven parallel robot and it is shown that the proposed controller is able to provide suitable tracking performance in practice.     

Adaptive robust pressure control of variable displacement axial piston pumps with a modified reduced-order dynamic model

Variable displacement axial piston pumps (VDAPPs) are wildly used in mobile working machines and they play a key role in machine’s energy-saving load sensing (LS) systems. Typically, electric load sensing (ELS) systems utilize traditional linear control methods, which only can realize limited control flexibility and performance. This study proposes and experimentally verifies an adaptive robust pressure control strategy for a VDAPP system. To facilitate the model-based controller design, a modified reduced-order dynamic modeling of VDAPPs is proposed. Furthermore, an adaptive robust backstepping control strategy is designed to deal with the dynamic nonlinearities and parametric uncertainties of the VDAPP system for achieving accurate pressure tracking. The controller design consists of two steps, processing the pump pressure tracking and the axial angle control, respectively. Comparative experiments and simulations with different working conditions were performed to validate the advantages of the proposed control strategy. The proposed controller achieved higher pressure tracking accuracy and it showed great capability in dealing with dynamic nonlinearities, uncertainties, and time-varying disturbances.     

Dynamics modeling and deviation control of the composites winding system

During the composites winding process, running speed, tension fluctuation and other factors often lead to the tape deviation. To improve the winding precision and eliminate the running deviation, lateral dynamics of the tape winding is analyzed and mathematical model of the rectifying system is established. Then, a novel adaptive sliding mode controller (ASMC) is proposed, and principle of this control scheme is employing two fuzzy systems to approximate the nonlinear functions and utilizing another two fuzzy systems to adjust the feedback gain (FG) and switching gain (SG). Stability and convergence of the control system can be guaranteed by the Lyapunov theory and Barbalat Lemma. Simulation and experimental results show that the designed ASMC has highest control precision and much smaller input chattering when compared with other controllers.     

A Hybrid-Type Variable-Structure Instantaneous Torque Control With a Robust Adaptive Torque Observer for a High-Performance Direct-Drive PMSM

This paper describes a novel instantaneous torque control scheme for a high-performance direct-drive permanent-magnet synchronous motor. The scheme consists of a robust adaptive instantaneous torque observer and a hybrid-type variable-structure instantaneous torque controller. First, to robustly obtain the instantaneous electromagnetic torque information, a robust adaptive torque observer is designed by considering all possible current model uncertainties. The observation gains and uncertainties prediction rules are derived in the sense of Lyapunov theory so that the stability of the proposed estimation scheme is fulfilled. Second, to ensure perfect tracking of the output torque and providing means in eliminating torque ripples, the frequency modes of the disturbances to be eliminated should be included in the stable closed-loop system. To achieve this objective, a hybrid-type variable-structure controller with internal model, for the flux harmonics and system uncertainties, is adopted. The hybrid controller shows better disturbance rejection without control chattering. Comparative evaluation results are presented to demonstrate the validity and effectiveness of the proposed instantaneous torque control scheme.     

Robust and fault-tolerant linear parameter-varying control of wind turbines

High performance and reliability are required for wind turbines to be competitive within the energy market. To capture their nonlinear behavior, wind turbines are often modeled using parameter-varying models. In this paper we design and compare multiple linear parameter-varying (LPV) controllers, designed using a proposed method that allows the inclusion of both faults and uncertainties in the LPV controller design. We specifically consider a 4.8 MW, variable-speed, variable-pitch wind turbine model with a fault in the pitch system.We propose the design of a nominal controller (NC), handling the parameter variations along the nominal operating trajectory caused by nonlinear aerodynamics. To accommodate the fault in the pitch system, an active fault-tolerant controller (AFTC) and a passive fault-tolerant controller (PFTC) are designed. In addition to the nominal LPV controller, we also propose a robust controller (RC). This controller is able to take into account model uncertainties in the aerodynamic model.The controllers are based on output feedback and are scheduled on an estimated wind speed to manage the parameter-varying nature of the model. Furthermore, the AFTC relies on information from a fault diagnosis system.The optimization problems involved in designing the PFTC and RC are based on solving bilinear matrix inequalities (BMIs) instead of linear matrix inequalities (LMIs) due to unmeasured parameter variations. Consequently, they are more difficult to solve. The paper presents a procedure, where the BMIs are rewritten into two necessary LMI conditions, which are solved using a two-step procedure.Simulation results show the performance of the LPV controllers to be superior to that of a reference controller designed based on classical principles.     

Robust adaptive tracking control of uncertain electrostatic micro-actuators with H-infinity performance

A novel adaptive robust tracking control scheme is proposed for a class of single-degree-of-freedom (1DOF) electrostatic micro-actuator systems in the presence of parasitics, parameter uncertainties and external disturbances. This method integrates the adaptive dynamic surface control and H-infinity control techniques. Based on this method, both the design procedure and the derived tracking controller itself are simplified, and the controller guarantees that the output tracking error satisfies the H-infinity tracking performance. In addition, the tracking accuracy can be adjusted by an appropriate choice of the design parameters of the controller. Simulation results show that prescribed transient output tracking performance can be achieved, and the closed-loop system exhibits good robustness to system uncertainties.     

导弹电液伺服机构的自适应模糊滑模跟踪控制

针对导弹电液伺服机构的跟踪控制问题,提出了一种自适应模糊滑模的设计方案.使用具有参数在线调节的自适应模糊控制,逼近滑模控制中的等效控制部分,并确定非线性控制项以保证系统的稳定性.根据滑模控制原理给出四条模糊规则,以平滑不连续控制,达到削弱抖振的目的.仿真结果表明了该方案的有效性.