Self-correcting wavelet neural network control of continuous rotary electro-hydraulic servo motor

In allusion to the problem of friction,leakage,vibration and noise existing in continuous rotary motor electro-hydraulic servo system,highly nonlinearity and uncertainties affecting the system performance,based on the transfer function of electro-hydraulic servo system,a kind of Pol-Ind friction model is proposed.The parameters of Pol-Ind friction model are identified and the accurate mathematical model of friction torque is obtained by experiment.The self-correcting wavelet neural network(WNN)controller is proposed,and Adam optimization algorithm is used to perform gradient optimization on scale factor and displacement factor in wavelet basis function,so as to improve the speed and precision of parameter optimization.Through comparative simulation analysis,it is clearly that the self-correcting WNN controller can effectively improve the frequency response and tracking accuracy of continuous rotary motor electro-hydraulic servo system.

Research of novel oscillating wire feeding system using the AC servo motor

With the background of the control of additional mechanical force droplet transfer in MIG/MAG welding, regarding the AC servo motor as core, a novel oscillating wire feeding system has been developed with excellent performances of control and dynamic acceleration which is tested. System constitution and operation principle are introduced in this paper. Influences of parameters on dynamic acceleration performance are analyzed and discussed emphatically, such as oscillating frequency, oscillating amplitude and draw-back speed. Experimental result indicates that according to the technique of welding control, the novel wire feeding system responds rapidly to various kinds of control orders of wire feeding and draw-back, and realizes flexible control of welding wire axial movement, including dynamic shifting,oscillating and so on.

Numerical simulation and experimental study on the leakage of continuous rotary electro-hydraulic servo motor

In order to study the influence of inlet and outlet pressure difference and triangular buffer groove on the internal leakage of continuous rotary electro-hydraulic servo motor,the flow field model of motor with and without triangular groove is established respectively.The mesh model is divided.The pressure distribution of the internal flow field under different pressure difference is analyzed by Fluent.Then,the gap leakage under different pressure difference is calculated,and the leakage curve is obtained.Finally,continuous rotary electro-hydraulic servo motor experimental system is built to conduct the internal leakage test,and the leakage under different pressure difference is measured and compared with the simulation results.The results show that the occurrence of leakage in the motor can be reduced by setting the triangular buffer groove on the flow plate,the simulation and experimental results are consistent.It can be concluded that the larger the pressure difference between the inlet and the outlet of the motor,the larger the gap leakage.The research lays foundation for the application of continuous rotary electro-hydraulic servo motor.

Object-tracking robot using ultrasonic sensor and servo motor

This paper proposes a method that rotation angle of servo motor and distance values of ultrasonic sensor are used for tracking an object in real-time while the robot keeps regular distance.Object detection distance widens by using ultrasonic sensors and object recognition,and movement of robot is controlled by angle of servo motor and distance of ultrasonic sensors.Not adopting the existing tracking methods:camera,laser-infrared(LRF)and many ultrasonic sensors,the proposed method proves that it is possible to track object using ultrasonic sensor and servo motor.Trajectory of robot is represented and analysed according to movement of object in limited conditions.

Thermal Performance of Mini Cooling Channels for High-Power Servo Motor with Non-Uniform Heat Dissipation

High-power servo motor is widely employed as a necessary actuator in flight vehicles.The urgent problem to be solved restraining the working performance of servo motor is no longer the torque and power,but the heat dissipation capability under high-power working conditions,which may cause the overheat,even burn down of motor or other potential safety hazards.Therefore,a structure of mini cooling channels with appropriate channel density is designed in accordance with the non-uniform heat flux of servo motor in this paper.Combined with the regenerative cooling method,the cryogenic fuel supercritical methane is served as the coolant,which is easy to be obtained from the propulsion system,and the heat from the servo motor can be transported to the combustion for reusing.According to the actual working cases of servo motor,a numerical model is built to predict the thermal performance of cooling channels.In order to better represent the secondary flow of coolant in the cooling channels,especially the turbulent mixed flow in the manifold,the k-εRNG model with enhanced wall treatment is employed resulting from its precise capacity to simulate the secondary and wall shear flow.On this basis,the heat transfer mechanism and thermal performance of cooling channels,as well as the influence of various heat flux ratios are investigated,which can offer an in-depth understanding of restraining excessive temperature rise and non-uniformity distribution of the servo motor.By the calculation results,it can be concluded that under the adjustment of the channel density according to the corresponding heat flux,the positive role of the appropriate channel density and the manifolds on heat transfer is manifested.Moreover,the maximum temperature difference of heating wall can be kept within an acceptable range of the servo motor.The heat transfer coefficient in the manifold is nearly 2–4 times higher compared with that in the straight cooling channels.The effect of buoyancy force cannot be neglected even in the manifold with turbulent mixed flow,and the pattern of heat transfer is mixed convection one in all the flow regions.The thermal resistance R and overall Nusselt number Nu are affected remarkably by all the operation parameters studied in the paper,except the pressure,while the overall thermal performance coefficientηdemonstrates differently.The strong impact of heat flux ratio is implied on thermal performance of the cooling channels.Higher heat flux ratio results in the stronger non-uniform temperature distribution.Meanwhile,only tiny temperature differences of the fluid and inner wall in manifolds among various heat flux ratios are demonstrated,resulting from the positive effect of mixture flow on heat transfer.

Continuous rotary motor electro-hydraulic servo system based on the improved repetitive controller

In order to suppress the periodic interference of the continuous rotary electro-hydraulic servo motor,this paper makes the motor tracking the periodic signals with high accuracy,and improves the influence of friction interference to the performance of continuous rotary electro-hydraulic servo motor.The mathematic model of the electro-hydraulic position servo system of the continuous rotary motor was established,and the compound control method was adopted based on the repetitive control,feed forward and PID to suppress the friction interference.Through the simulation,the result confirms that the compound control method decreases the tracking error of the system,increases the robust performance of the system and improves the performance of the continuous rotary electro-hydraulic servo motor.

Influence of Magnetic Reluctances of Magnetic Elements on Servo Valve Torque Motors

The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.

The adaptive control using BP neural networks for a nonlinear servo-motor

The servo-motor possesses a strongly nonlinear property due to the effect of the stimulating input voltage, load-torque and environmental operating conditions. So it is rather difficult to derive a traditional mathematical model which is capable of expressing both its dynamics and steady-state characteristics. A neural network-based adaptive control strategy is proposed in this paper. In this method, two neural networks have been adopted for system identification （NNI） and control （NNC）, respectively. Then, the commonly-used specialized learning has been modified, by taking the NNI output as the approximation output of the servo-motor during the weights training to get sensitivity information. Moreover, the rule for choosing the learning rate is given on the basis of the analysis of Lyapunov stability. Finally, an example of applying the proposed control strategy on a servo-motor is presented to show its effectiveness.

Application of Ultrasonic Motor to Control of Moment Gyroscope Gimbal Servo System

Attitude control system is one of the most important subsystems in a spacecraft.As a key actuator,the control moment gyroscope(CMG)mainly determines the performance of attitude control system.Whereas,the control accuracy and output torque smoothness of the CMG depends more on its gimbal servo system.Considering the constraints of size,mass and power consumption for a small satellite,here,a mini-CMG is designed,in which the gimbal servo system is driven by an ultrasonic motor.The good performances of the CMG are obtained by both the ultrasonic motor and the rotary inductosyn.The direct drive of gimbal improves its dynamic performance,with the output bandwidth above 20 Hz.The angular and speed closed-loop control obtains the 0.02°/s gimbal rate,and the output torque resolution better than 2×10^(-3) N·m.The ultrasonic motor provides 1.0N·m self-lock torque during power-off,with 12arc-second position accuracy.

Blank Holder Force Control System Driven by Servo-Motor

Blank holder force (BHF) control is used to prevent wrinkles of sheet metal in deep drawing process. Based on a novel conception of BHF control technique driven by servo-motor, a new BHF device with six-bar linkage mechanism has been designed and manufactured. Whole control system of the new BHF technique was developed, and the basic structure of the hardware configuration of the system was given. Software analysis, implementation and division of the functional modules have been done. Also, the control software in data acquisition and processing module has been developed in the relevant technology of the BHF control system for the requirements of real-time, stability and accuracy. By the new BHF device combined with the hardware and the software system, the BHF can be regulated accurately variation with the predefined BHF profile in deep drawing process.

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。

含有柔性负载的电驱动系统建模与控制策略

为了抑制伺服电机启动和运行过程中产生的转速波动和振动,提出了一种基于极点配置的PI控制策略.首先,根据基尔霍夫电压定律和拉格朗日原理建立了伺服电机与柔性负载的整体动力学模型,并通过拉普拉斯变换计算系统的传递函数.其次,通过设计控制器的参数,分析了采用相同幅值的极点配置方法对控制效果的影响.最后,通过与传统的Z-N方法和无控制方法进行对比,验证了该极点配置方法的优势.通过数值仿真和实验研究,实现了对伺服电机启动和运行过程中产生的角度误差的控制,有效抑制了电机转速的波动,保证了系统的稳定性.

智能型弯箍机控制系统开发

针对传统弯箍机存在的加工精度低、用户定制响应能力弱、远程运维功能缺失等问题,提出利用伺服控制、PLC、人机交互以及云平台等技术设计并开发了一种智能型弯箍机电气控制系统。系统以PLC作为核心控制器,利用三相交流异步电动机完成剪切任务,伺服电机驱动完成送丝和折弯任务;同时,借助4G通信模块,实现了远程加工状态监控、设备远程预测性运维与实时报警等管控功能。系统中通过引入弯曲长度、角度的补偿系数,结合全闭环伺服控制,保证了箍筋成品的加工精度。

Advanced Electrical Motors and Control Strategies for High-quality Servo Systems-A Comprehensive Review

Recent technological advancements have propelled remarkable progress in servo systems,resulting in their extensive utilization across various high-end applications.A comprehensive review of high-quality servo system technologies,focusing specifically on electrical motor topologies and control strategies is presented.In terms of motor topology,this study outlines the mainstream servo motors used across different periods,as well as the latest theories and technologies surrounding contemporary servo motors.In terms of control strategies,two well-established approaches are presented:field-oriented control and direct torque control.Additionally,it discusses advanced control strategies employed in servo systems,such as model predictive control(MPC)and fault tolerance control,among others.

考虑电压电流限制的伺服电机无纹波转矩控制

针对伺服系统无刷电机正弦电流转矩控制纹波较大的问题,提出了一种无刷伺服电机在任意反电动势波形下的无纹波转矩控制,实现了电机驱动器在有限电压、电流范围内的功率损耗最小。首先,建立了有限电压、电流范围内的电机模型,推导了电压、电流范围边界的不等约束条件;其次,利用拉格朗日乘数法求解等效二次规划问题,提出了最优转矩控制策略;最后,在三相18极同步电机的实验平台上进行了3种情况的实验验证。结果表明,所提控制策略在相电压、电流饱和时,仍能实现转矩的精确控制,输出期望转矩;在发生单相故障时,可以隔离故障相,同时通过优化励磁电流使非故障相达到预期的转矩输出,减小了转矩纹波。

基于动态理论模型的电液伺服加载前馈补偿复合控制系统

针对一般电液伺服系统存在的非预期负载扰动和非线性干扰等问题,为了提高系统的自适应能力和动态响应的品质,减小系统跟踪和输出响应的误差,提出了一种基于动态理论模型的电液伺服加载前馈补偿复合控制方法。首先,阐释了电液伺服试验台的结构组成及其数学模型,分析了系统力矩控制和位置控制的结构关系;然后,论证了自适应前馈补偿复合控制的伺服原理,阐述了以调速理论模型和实际模型的误差函数作为调速依据的前馈补偿和复合控制的原理和方法;最后,进行了系统仿真,同时为了验证基于动态理论模型的自适应前馈补偿复合控制策略的合理性和有效性,对伺服系统进行了加载试验。研究结果表明:采用该复合控制策略可以精确算出对伺服马达进行转速补偿的基准值和调整参数,系统动态响应速度比采用传统闭环控制算法提高了8%以上;系统控制器自适应能力和抗扰动性能也明显优于采用传统PI闭环控制及模糊PI闭环控制算法的系统;通过对比分析0.2 Hz和0.5 Hz的正弦响应曲线可知,该系统的位置跟踪曲线性能最优,控制精度最高,实际输出值的误差也最小。

适用于栅格舵焊缝检测的超声扫查装置

针对栅格舵焊缝的超声无损检测需求,为解决当前人工手动扫查检测及缺陷评定中的可靠性低、周期长和系统成熟度低等问题,在阵列超声主机、换能器及成像软件的开发基础上研制了一种适用于栅格舵焊缝超声检测的装置。该装置以PLC(可编程逻辑控制器)为控制核心,采用GSKLink通讯协议实现对于机器人、伺服电机的控制,同时根据栅格舵焊缝结构设计自动化工艺运动流程,实现目标的自动化检测。通过实际运行该装置并将其应用于生产,证明了该装置能够满足栅格舵焊缝的自动超声检测需求,大大提高了栅格舵的生产效率。

基于滑窗滤波器的改进MRAS转动惯量辨识

交流伺服电机在负载突变时,传统模型参考自适应(model reference adaptive system,MRAS)不能同时满足辨识精度和收敛速度两方面的需求,鉴于此,提出一种基于滑窗滤波器的改进MRAS转动惯量辨识策略。首先,利用曲率模型(curvature model,CM)对电机的负载扰动进行实时估测;其次,对传统MRAS法进行改进,基于滑窗滤波器原理设置变增益机制的判断依据,使负载突变时系统自动调整自适应率中的增益系数,确保转动惯量被快速、精准的辨识;最后,通过仿真和搭建实平台对所提方法进行验证,结果证明此方法不仅具备较高的辨识精度,同时收敛速度快,很好的克服了传统方法的不足,表现出优异的动态性能。

飞机拦阻系统的改进及建模分析

针对纯机械式液压拦阻系统不能对不同质量和降落速度的飞机快速有效拦阻的问题,对原来的系统进行改进,采用电液伺服阀替换原来的凸轮阀和针阀,采用伺服电机控制的液压泵替换原来的制动盘传动比控制的液压泵,建立改进后的飞机拦阻系统的数学模型,并用MATLAB/Simulink建立仿真模型,对飞机速度、飞机拦停距离和飞机过载等受控参数的变化规律进行了仿真分析,模拟了飞机拦阻系统的工作过程,对拦阻系统的性能进行了仿真验证。结果表明:改进的拦阻系统对多种型号飞机在拦阻距离、飞机加速度、飞机速度、拦阻力和刹车压力均满足预设的拦阻指标且曲线平稳、没有大的突变。

基于MCGS组态软件的板材雕刻机控制系统设计

板材雕刻机是一种用于在板材上进行雕刻、切割、剪裁的机器。为提高雕刻机的速度和精度,并研究其在控制方面的应用,通常采用PLC控制伺服电机带动刀头进行精确的雕刻操作。板材雕刻机可以根据预先设计好的图案或模型进行雕刻,广泛应用于家具制造、建筑装饰、艺术品制作等领域。在板材雕刻机的控制系统中,通过MCGS组态软件,可以直观地反映雕刻过程,并精确地控制雕刻机进行预设图案的雕刻。通过优化控制、调整运动路径和采用高精度的传感器和编码器,可以大大提高雕刻机的速度和精度,实现更精细的雕刻效果。控制系统还能实时监测刀头位置和状态,及时调整雕刻参数,保证雕刻结果的准确性。