基于扩张状态观测器和抗饱和输入的伺服电机等效反步滑模控制

为了提高伺服电机系统的动态响应速度、抗干扰能力,解决输入饱和的问题,课题组基于扩张状态观测器(extended state observer,ESO)和抗饱和输入(anti-saturation input,ASI)辅助系统设计了伺服电机的运动控制方案。首先,建立了伺服电机的数学模型,将系统阻尼和系统不确定性归为扰动,将扰动设为系统的扩张状态;然后在等效反步滑模控制(backstepping sliding mode control,BSMC)的基础上,引入了ASI辅助系统和ESO,解决输入饱和问题,并抑制内、外干扰;采用双曲正切饱和函数替换符号函数以减小滑模控制的抖振;通过李雅普诺夫稳定性方法检验所提出控制器的稳定性。最后,将基于ESO和ASI的等效反步滑模控制与比例积分微分(proportional integral differential,PID)控制、滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:相较于传统PID和SMC控制器,课题组所设计的控制器可以实现伺服电机的无超调快速响应,解决了输入饱和问题,并具有较好的抗干扰能力和减小输入冲击的作用。

基于双容液位系统的神经网络反步滑模与PCH协同控制

针对工业生产过程的实际需求,该文研究了具有参数不确定性和外部未知干扰的双容液位系统的控制问题。首先,设计了一种反步滑模控制策略(BSMC),以提高控制系统的速度;其次,利用神经网络(NN)逼近系统的非线性函数,以求解系统参数的不确定性和未建模的动态扰动;第三,设计了一种端口控制的哈密顿(PCH)控制策略,以保证控制系统的稳态控制精度;最后,提出了一种协同优化控制方法,它结合了这两种控制方法,充分发挥了神经网络反步滑模(NNBSMC)算法的快速性和PCH算法的高稳态精度。仿真结果表明,利用神经网络反步滑模控制和端口控制哈密顿协同优化控制(NNBSMC+PCH)可以使系统兼顾两种控制器的优点。

Backstepping sliding mode control with self recurrent wavelet neural network observer for a novel coaxial twelve-rotor UAV

The robust attitude control for a novel coaxial twelve-rotor UAV which has much greater payload capacity,higher drive capability and damage tolerance than a quad-rotor UAV is studied. Firstly,a dynamical and kinematical model for the coaxial twelve-rotor UAV is designed. Considering model uncertainties and external disturbances,a robust backstepping sliding mode control( BSMC) with self recurrent wavelet neural network( SRWNN) method is proposed as the attitude controller for the coaxial twelve-rotor. A combinative algorithm of backstepping control and sliding mode control has simplified design procedures with much stronger robustness benefiting from advantages of both controllers. SRWNN as the uncertainty observer is able to estimate the lumped uncertainties effectively.Then the uniformly ultimate stability of the twelve-rotor system is proved by Lyapunov stability theorem. Finally,the validity of the proposed robust control method adopted in the twelve-rotor UAV under model uncertainties and external disturbances are demonstrated via numerical simulations and twelve-rotor prototype experiments.

A switching-based backstepping sliding mode control for space manipulator in presence of gravity variation

A novel switching-based backstepping sliding mode control(SBSMC) scheme is devised for the space manipulator exposed to different gravity.With a view to distinct differences in dynamics properties when the operating conclition of space manipulator changer,the space manipulator can be thought of as a system composed of two subsystems,the ground subsystem and the space subsystem.Two different types of backstepping sliding mode(BSM) controllers are designed,one is suited for the ground subsystem and the other is for the space one.The switching between two subsystems can be implemented automatically when the switching mechanism is triggered,and the controllers for their subsystems experience synchronous switching.In this way,the space manipulator always has good behaviors in trajectory tracking.Moreover,multi-Lyapunov functions are introduced to prove the stability of this switching approach.According to simulation results,the method constructed in this research has better performance in control precision and adaptability compared with proportional-derivative(PD) control.

Modeling and robust adaptive control for a coaxial twelve-rotor UAV

Compared with the quad-rotor unmanned aerial vehicle (UAV), the coaxial twelve-rotor UAV has stronger load carrying capacity, higher driving ability and stronger damage resistance. This paper focuses on its robust adaptive control. First, a mathematical model of a coaxial twelve-rotor is established. Aiming at the problem of model uncertainty and external disturbance of the coaxial twelve-rotor UAV, the attitude controller is innovatively adopted with the combination of a backstepping sliding mode controller (BSMC) and an adaptive radial basis function neural network (RBFNN). The BSMC combines the advantages of backstepping control and sliding mode control, which has a simple design process and strong robustness. The RBFNN as an uncertain observer, can effectively estimate the total uncertainty. Then the stability of the twelve-rotor UAV control system is proved by Lyapunov stability theorem. Finally, it is proved that the robust adaptive control strategy presented in this paper can overcome model uncertainty and external disturbance effectively through numerical simulation and prototype of twelve-rotor UAV tests.

LncRNA CASC7/miR-98-5p/SIRT3轴调控慢性阻塞性肺疾病大鼠气道炎症反应和平滑肌细胞变化

目的:探讨LncRNA CASC7/miR-98-5p/SIRT3轴对慢性阻塞性肺疾病(COPD)大鼠气道炎症反应和支气管平滑肌细胞(BSMCs)的影响。方法:收集临床标本用于检测CASC7、miR-98-5p、SIRT3的表达。双荧光素酶报告实验用于验证CASC7/miR-98-5p、miR-98-5p/SIRT3之间的靶向关系。建立COPD大鼠模型,ELISA检测大鼠血清中炎症相关因子表达。对BSMCs进行分组转染,使用ELISA、CCK-8、流式细胞术检测细胞炎症因子的表达、增殖能力、凋亡情况。Western blot检测PI3K信号通路相关因子的表达。结果:相对于正常样本,CASC7、SIRT3在COPD中低表达,miR-98-5p高表达,且CASC7、SIRT3与miR-98-5p的表达均呈负相关(均P<0.05)。CASC7能够调控miR-98-5p/SIRT3表达并影响PI3K信号通路变化。过表达CASC7或miR-98-5p抑制剂可阻滞炎症因子分泌和BSMCs增殖,促进BSMCs凋亡,但这种效果被SIRT3敲减部分挽救(均P<0.05)。结论:CASC7能够通过调控miR-98-5p/SIRT3轴进而减少气道炎症因子分泌,抑制BSMCs的增殖,并诱导其凋亡,CASC7在COPD的进展中扮演重要角色。

Backstepping sliding mode control of a variable speed wind turbine for power optimization

To optimize the energy capture from the wind,wind turbine(WT)should operate at variable speed.Based on the wind speed,the operating regions of the WT are divided into two parts:below and above the rated wind speed.The main aim at below rated wind speed is to maximize the energy capture from the wind with reduced oscillation on the drive train.At above rated wind speed,the aim is to maintain the rated power by using pitch control.This paper presents the control of WT at below rated wind speed by using backstepping sliding mode control(BSMC).In BSMC,generator torque is considered as the control input that depends on the optimal rotor speed.Usually,this optimal rotor speed is derived from effective wind speed.In this paper,effective wind speed is estimated from aerodynamic torque and rotor speed by using the modified Newton Rapshon(MNR)algorithm.Initially,a conventional sliding mode controller(SMC)is applied to the WT,but the performance of the controller was found to be less robust with respect to disturbances.Generally,WT external disturbance is not predictable.To overcome the above drawback,BSMC is proposed and both the controllers are tested with mathematical model and finally validated with the fatigue,aerodynamics,structures,and turbulence(FAST)WT simulator in the presence of disturbances.From the results,it is concluded that the proposed BSMC is more robust than conventional SMC in the presence of disturbances.

AMPK对膀胱逼尿肌细胞缝隙连接蛋白43的下调及膀胱过度活动症的调控机制

目的观察AMPK激活对小鼠膀胱逼尿肌细胞(BSMC)中缝隙连接蛋白43表达的影响,探讨AMPK在膀胱过度活动症(OAB)治疗中的潜在作用和机制。方法利用不同的AMPK激动剂刺激BSMC细胞,应用RT-PCR和Western blot检测AMPK活化对Cx43表达的影响。利用PDGF建立小鼠病理模型,观察AMPK对PDGF诱导的Cx43表达的作用。利用荧光酶素试验检测AMPK对Cx43启动子活性的影响。结果 AMPK活化降低小鼠BSMC中Cx43 mRNA和蛋白的表达水平,显著抑制PDGF诱导BSMC细胞中Cx43表达,抑制正常或者PDGF刺激的BSMC细胞中Cx43启动子活性。结论 AMPK通过抑制Cx43启动子活性从而降低小鼠BSMC细胞Cx43 mRNA和蛋白表达水平,靶向调控AMPK很可能成为治疗OAB的新方向。