Improved Hybrid Robust Control Method for the Electromechanical Actuator in Aircrafts

In the flight process of aircrafts, their electromechanical actuators（EMA） must have the ability of enduring uncertainties caused by factors such as load disturbance, the variation of work temperature and the EMA＇s nonlinearity. At present, in order to increase the EMA＇s robustness on the uncertainties, the H, control method has been applied in aircrafts. The major problems with standard H∞ control lie in the large overshoot of step response and the high orders of the controller. For the purpose of addressing the two problems, this paper investigates several kinds of robust control strategies of the EMA. A mathematical model of the EMA is first built, and then with MATLAB software a H∞ controller and an improved hybrid robust controller composed of a reduced order H∞controller and a lead compensator are designed. In order to make a scientific comparison of the control effects of H∞ controller, hybrid controller and classic proportion-integral-differential（PID） controller, a simulation research is made in respect of the open loop frequency response and the closed loop step response of the three controllers. For comparing the robustness of the three controllers, the load torque is entered as a disturbance and the disturbance response of error and control input are thus obtained. The experiments with the three controllers are also conducted. Through giving the EMA a command and a disturbance torque successively, the transient response and disturbing process of EMA are recorded. The simulation and experiment results show that with the help of the hybrid controller, the EMA not only guarantees good dynamic characteristics, but also has strong robustness of disturbance rejection. Therefore, the excogitated H∞ hybrid control method effectively solves the problem of large overshoot in dynamic response, and moderately meets the requirement of overcoming the uncertainties in the EMA of aircrafts.

Experimental study and electromechanical model analysis of the nonlinear deformation behavior of IPMC actuators

This paper develops analytical electromechanical formulas to predict the mechanical deformation of ionic polymer-metal composite (IPMC) cantilever actuators under DC excitation voltages. In this research, IPMC samples with Pt and Ag electrodes were manufactured, and the large nonlinear deformation and the effect of curvature on surface electrode resistance of the IPMC samples were investigated experimentally and theoretically. A distributed electrical model was modified for calculating the distribution of voltage along the bending actuator. Then an irreversible thermodynamic model that could predict the curvature of a unit part of an IPMC actuator is combined with the electrical model so that an analytical electromechanical model is developed. The electromechanical model is then validated against the experimental results obtained from Pt- and Ag-IPMC actuators under various excitation voltages. The good agreement between the electromechanical model and the actuators shows that the analytical electromechanical model can accurately describe the large nonlinear quasi-static deflection behavior of IPMC actuators.

Large nonlinear deflection behavior of IPMC actuators analyzed with an electromechanical model

This study presents an electromechanical engineering model for the analysis of the large deflection curves of ionic polymer-metal composite(IPMC)cantilever actuators under direct current(DC)voltages.In this paper,the longitudinal normal strain performance of the material was investigated using digital image correlation on a micro-scale.The deflection of the actuator is analytically obtained with the application of an elliptic integration method based on the relationship between strain gradient and excitation voltage,and the minimum excitation voltage is derived based on the assumption that the actuators have small deformations.The validity of the electromechanical model is then justified with the experimental results obtained from Pt-and Ag-IPMC actuators at various excitation voltages.The findings of this study confirm that the introduced electromechanical model can accurately describe the large nonlinear deflection behavior of IPMC actuators.

Design and fabrication of a bistable electromagnetic microactuator

An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. Mechanical and magnetic analysis are carried out on the actuator, and the device with a size of 2.2 mm × 2.5 mm is fabricated with the UV-LIGA technology. The test results show that a current pulse with an amplitude of 70 mA is needed for actuator＇ s switching between the two stable states, and the switching time is no more than 6 ms. Displacement of the end of cantilever is about 15 μm.

基于分数阶自适应神经网络的电动舵机伺服系统摩擦干扰补偿控制

摩擦干扰力矩影响电动舵机伺服系统的跟踪性能,造成位置和速度跟踪偏差,甚至可能导致伺服系统不稳定。针对摩擦力矩干扰下的电动舵机伺服系统跟踪性能差的问题,本文提出了一种分数阶自适应神经网络摩擦补偿算法(FOANN),估计并补偿摩擦干扰力矩。首先,建立基于LuGre模型的电动舵机伺服系统模型,利用径向基神经网络估计模型中的不可测状态变量。其次,设计FOANN摩擦补偿控制器,利用李雅普诺夫稳定性理论证明电动舵机闭环系统的稳定性。最后,利用仿真和实验平台,对比分析了FOANN、传统PD控制和模型自适应控制的性能。结果表明,基于本文所提出的FOANN摩擦力矩补偿控制算法,电动舵机伺服系统的位置跟踪误差和速度跟踪误差均大幅减小,FOANN算法能够有效估计并补偿摩擦力矩,降低摩擦干扰对电机舵机伺服系统的影响,提高伺服系统的动态性能。

含实时电流补偿的开关磁阻式机电作动器自适应PI控制

针对传统控制算法难以克服开关磁阻电机的非线性并有效抑制转向叶片的负载扰动,因而无法对开关磁阻式机电作动器进行快速高精度位置跟踪控制的问题,提出了一种含实时电流补偿的自适应PI控制器。首先,通过负载观测器对作用于转向叶片上的空气动力负载进行实时估算,进而转化为电流环的实时补偿电流来抑制负载扰动的影响;然后,基于开关磁阻电机的转矩电流特性拟合曲线与实时电流反馈值对转速环PI参数进行自适应最优调节,从而削弱了开关磁阻电机的非线性,增强了机电作动器的转速调节性能;最后,通过引入位置前馈环节,有效提高了机电作动器的响应速度和位置跟踪精度。仿真和实验结果表明:相较于传统PI控制器、自适应PI控制器和含前馈环节的自适应PI控制器,所提控制器将开关磁阻式机电作动器的响应速度分别提高了49.3%、44.4%和30%,位置跟踪精度分别提高了54.8%、49.2%和2.9%,从而使得机电作动器具备更强的位置跟踪性能。

基于天牛须BP神经网络的船舶电动舵机自抗扰控制

将自抗扰控制器(ADRC)引入到智能船舵机控制优化问题中,同时将神经网络嵌入到自抗扰控制,针对电动舵机快响应、非线性的特点提出一种神经网络自抗扰控制。将天牛须搜索(BAS)寻优能力强的特性与BP神经网络中的权值与阈值寻优过程相结合,建天牛须BP神经网络自抗扰控制器,弥补了BP神经网络训练时间较长、收敛速度较慢的问题。以船舶电动舵机系统作为被控对象在该控制器下的舵机系统的控制性能得到了提升,控制精度高无超调同时具有良好的鲁棒性,同时建立的BAS-BP神经网络自抗扰控制器对于实际应用具有指导意义。

基于预设性能的飞机全电刹车系统滑模控制

针对飞机全电防滑刹车系统具有较强的非线性特征,以及机电作动器(EMA)中存在的干扰不利于系统稳定性,提出一种有限时间预设性能反演滑模控制方法。在合理简化的基础上,建立含滑移率子系统和EMA子系统的飞机全电防滑刹车系统的数学模型,并引入有限时间预设性能函数;利用预设性能反演控制方法设计滑移率控制器,获得参考刹车压力控制率,保证滑移率跟踪误差在有限时间内收敛到预设范围内;为跟踪参考刹车压力,利用非奇异终端滑模控制方法设计EMA控制器,针对EMA中存在的干扰,设计扩张状态观测器估计,并在控制器中进行补偿,提高控制器的鲁棒性和控制精度;通过干跑道和冰跑道2种情况下的数值仿真验证所提方法控制效果。

低成本高性能EMA相关技术最新研究进展

ACTUATION 2015是欧盟为推动EMA技术发展而进行的一个国际合作项目,主要从EMA模型构建技术、关键模块设计技术、健康监测技术以及标准化等方面来提升EMA的设计水平和安全可靠性、降低EMA综合成本。文中依照ACTUATION 2015 4个研究方向,从4个方面介绍了ACTUATION 2015项目中低成本高性能EMA相关技术研究的典型成果,以期为国内相关工作者的研究开发和应用提供一定启发。

余度机电作动器(EMA)系统BIT设计分析

讨论了一种由稀土永磁无刷电机构成的具有余度结构的机电作动器（EMA）系统的BYF设计问题。首先分析了该系统的测试性，然后根据BIT功能要求提出了故障检测方法。

锥形电活性聚合物薄膜作动器的力电响应研究

以一款锥形电活性聚合物薄膜作动器为研究对象,选用Ogden材料模型对作动器进行数值计算。控制外力变化,对薄膜在变形状态下的应变量、厚度及临界电场强度进行分析,研究了预拉伸对薄膜力电稳定性的影响。结果表明:外力增加会显著提高薄膜内各点的径向应变,减小膜厚,并使得临界电场强度的分布发生改变;薄膜预拉伸程度的增加,也会提高薄膜临界电场强度,使得薄膜的力电稳定性得到增强。

Modelling and simulation of flight control electromechanical actuators with special focus on model architecting, multidisciplinary effects and power flows

In the aerospace field, electromechanical actuators are increasingly being implemented in place of conventional hydraulic actuators. For safety-critical embedded actuation applications like flight controls, the use of electromechanical actuators introduces specific issues related to thermal balance, reflected inertia, parasitic motion due to compliance and response to failure. Unfortunately, the physical effects governing the actuator behaviour are multidisciplinary, coupled and nonlinear. Although numerous multi-domain and system-level simulation packages are now available on the market, these effects are rarely addressed as a whole because of a lack of scientific approaches for model architecting, multi-purpose incremental modelling and judicious model implementation. In this publication, virtual prototyping of electromechanical actuators is addressed using the Bond-Graph formalism. New approaches are proposed to enable incremental modelling,thermal balance analysis, response to free-run or jamming faults, impact of compliance on parasitic motion, and influence of temperature. A special focus is placed on friction and compliance of the mechanical transmission with fault injection and temperature dependence. Aileron actuation is used to highlight the proposals for control design, energy consumption and thermal analysis, power network pollution analysis and fault response.

Output constrained IMC controllers in control systems of electromechanical actuators

Electromechanical actuators are widely used in many industrial applications. There are usually some constraints existing in a designed system. This paper proposes a simple method to design constrained controllers for electromechanical actuators. The controllers merge the ideas exploited in internal model control and model predictive control. They are designed using the standard control system structure with unity negative feedback. The structure of the controllers is relatively simple as well as the design process. The output constraint handling mechanism is based on prediction of the control plant behavior many time steps ahead. The mechanism increases control performance and safety of the control plant. The benefits offered by the proposed controllers have been demonstrated in real-life experiments carried out in control systems of two electromechanical actuators： a DC motor and an electrohydraulic actuator.

EMA、EHA和IAP三种作动器比较

介绍了EMA、EHA和IAP三种作动器,并对其进行了比较,介绍了国外的比较研究,最后对战术导弹上对三种作动器的选择进行了分析。

Low-and high-field electromechanical responses of relaxor-based multicomponent ceramics for application in multiregime actuators

The electromechanical responses of multicomponent solid solutions Pb_(0.95)Ba_(0.05)(Mg_(1/3)Nb_(2/3))_(0.471)(Zn_(1/3)Nb_(2/3))_(0.102)(Ni_(1/3)Nb_(2/3))_(0.152)Ti_(0.275)O_(3)in low and high electric fields were studied.In both cases,significant electromechanical responses are observed.In particular,the maximum values of the large-signal piezoelectric coefficient d_(33)reach 1600 m/V at very low values of the electric field(≈5 kV/cm).The observed features of the electromechanical responses of the studied ceramics are advantages in terms of their possible application in actuators.

飞机EMA过载保护装置摩擦片的优化设计研究

为提高飞机大功率EMA摩擦盘的稳定性和实用性,对摩擦盘内的摩擦片进行了优化设计与研究。首先根据加权因子法分析,选定最适合飞机上使用的摩擦片材料为铁铜基粉末冶金摩擦材料;其次采用粉末冶金材料激光表面增强技术,提高了金属粉末冶金材料的表面质量,从而提高了在大功率负载作用下材料的稳定性;再次通过电控摩擦试验,采用改变外加电场的方法来改变金属材料表面摩擦因数;最后通过摩擦片有限元分析来判断摩擦片各处的受力情况,分析检验摩擦片强度,最终设计出合理的摩擦片。结果表明,设计出的摩擦片具有高稳定性、高耐热性和高强度等特性,增强了摩擦盘的稳定性和实用性。

无人机全电刹车系统级联快速终端滑模控制

无人机防滑刹车系统具有高阶非线性、强耦合以及参数时变性等特点,会对无人机的地面滑跑性能造成不利影响。提出了一种无人机全电防滑刹车系统快速终端滑模控制方法,实现对最佳滑移率的准确跟踪,并保证刹车系统的稳定性。建立了无人机全电刹车系统整体模型,在控制器设计过程中避免了对地面结合系数拟合公式的依赖。结合反演控制的思想,逐级设计了快速终端滑模控制器实现对滑移率以及刹车压力参考值的精确跟踪,并通过Lyapunov稳定性理论证明了控制器的稳定性。通过仿真测试验证了所提出控制策略的有效性。

航空永磁电驱动系统比例谐振型自抗扰速度控制器设计

襟缝翼机电作动器是飞机高升力系统中的关键运动部件,其速度控制对襟缝翼的姿态调节十分重要。然而,襟缝翼机电作动器易受到翼面周期性或非周期性气动载荷干扰,传统的比例积分型速度控制器性能实现受限。为此,本文提出一种基于比例谐振自抗扰控制器(ADRC),在抑制非周期性干扰基础上还可抑制特定次周期性干扰。周期性干扰通过采用比例谐振控制的扩展状态观测器来估计。通过试验,比较了比例积分型控制器、传统线性自抗扰控制器和比例谐振型自抗扰控制器的控制性能,验证了本文所提出的方法可以显著抑制干扰、提高机电作动器的速度控制精度,为飞机平稳起降提供技术支撑。

基于集成学习方法的机电作动器故障诊断框架

针对飞行器综合性能不断提高的发展需求,对机载机电作动器(EMA)进行健康管理尤为关键。文章以EMA作为研究对象,重点研究基于集成学习方法的故障诊断框架来解决飞行器可能存在的健康管理问题:对比不同集成学习策略间的优劣,提出一种以Boosting集成学习方法为核心的故障诊断框架。该方法的建立以XGBoost、LightGBM和CatBoost模型为基础,相较于时下流行的深度学习框架,其占用的计算资源更少,模型的可解释性更强。试验结果表明,该框架相较于传统机器学习方法准确率提高10%,相较于深度学习方法训练时间减少75%,且内存占用率更低,具有较强的工程应用价值。

基于改进径向基网络的电动舵机滑模控制

针对电动舵机小角度平顶现象引发的弹道抖振问题,以小角度平顶问题为中心,对平顶问题展开研究分析,并提出了一种改进的径向基滑模控制(RBF-SMC)方法,通过设计滑模控制器,削弱摩擦和间隙的不利影响,以提高系统的跟踪精度;针对模型中的不确定项,引入径向基网络进行逼近,提高控制精度,同时降低滑模控制算法的抖振问题;为提高径向基网络的迭代效率,使用2个单参数代替权值矩阵,大幅减少需要迭代估计的参数数量。最后,搭建电动舵机系统实验平台,采用PID控制器和改进的径向基滑模控制器进行对比分析。实验结果表明,相比于传统PID算法,在跟踪0.1°4 Hz正弦指令时,采用改进的径向基滑模控制算法将位置平顶时间从64 ms降低至9 ms,位置跟踪误差从0.123°降低至0.04°;在半物理试验时,弹道抖动频率从14.7 Hz降低至6.8 Hz,抖振幅值从0.079°降低至0.034°。采用改进的径向基滑模控制能有效提高系统的跟踪性能,削弱平顶问题,抑制弹道极限环震荡。