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.

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.

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.

Research on improved active disturbance rejection control of continuous rotary motor electro-hydraulic servo system

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors,such as dynamic uncertainty and parameter perturbation,an improved active disturbance rejection control(ADRC)strategy was proposed.The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor.Then the three parts of ADRC were improved by parameter perturbation and external disturbance;the fast tracking differentiator was introduced into linear and non-linear combinations;the nonlinear state error feedback was proposed using synovial control;the extended state observer was determined by nonlinear compensation.In addition,the grey wolf algorithm was used to set the parameters of the three parts.The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes,which lay foundation for the motor application.

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.

基于级联惯性负载转矩观测器的永磁伺服电机复合抗扰控制

针对永磁伺服电机在运行时位置跟踪精度差和抗干扰性能弱等问题,提出一种模型预测位置控制与非奇异快速终端滑模速度控制相结合的复合模型预测控制策略。该控制策略采用非奇异快速终端滑模设计速度控制器,以有效提高响应速度及系统鲁棒性;采用模型预测位置控制提高位置跟踪精度;同时,采用基于转动惯量观测和负载转矩观测器相结合的级联惯性负载转矩观测器观测负载转矩并进行前馈补偿,进一步提高系统的抗干扰性能。通过仿真和实验结果可得,所提复合模型预测控制可有效提高永磁伺服电机的动态响应速度和抗负载扰动能力。

Pressure impact characteristic of vane type continuous rotary motor under different buffer structures

In order to solve the problem of pressure shock on the continuous rotary electro-hydraulic servo motor,the mathematical models of pressure gradient under the structure of pre-compressed chamber and U-shaped groove were established.The optimal structure dimensions of the pre-compressed chamber and the U-shaped groove were determined.The fluid models were established by Solidworks under the four structures of triangular groove,triangular groove with pre-compression chamber,U-shaped groove and U-shaped groove with pre-compression chamber.Simulation analysis of depressurization process of fluid models was performed based on FLUENT.The pressure nephograms of different buffer structures were compared and analyzed,and the pressure change curves and pressure gradient change curves in the process of depressurization were obtained.The results show that the optimal edge length of the pre-compressed chamber of continuous rotary electro-hydraulic servo motor is 20 mm in the process of decompression.The pressure reduction effect is the best when the width of the U-shaped groove is 1.5 mm and the depth is 1.65 mm.The U-shaped groove structure with pre-compression chamber is more conducive to alleviate the pressure shock phenomenon of the motor compared with different combine buffer structures.

Shafting misalignment fault diagnosis by means of motor speed signal and SVD-HT method

Aiming at the deficiency of diagnosis method based on vibration signal,a novel method based on speed signal with singular value decomposition and Hilbert transform(SVD-HT)is proposed.The fault diagnosis mechanism based on the speed signal is obtained by constructing the shaft misalignment fault model firstly.Then the SVD-HT method is applied to the processing of the speed signal.The accuracy of the SVD-HT method is verified by comparing the diagnosis results of the order spectrum method and the SVD-HT method.After that,the diagnosis results based on vibration signal and speed signal under no-load and load patterns are compared.Under the no-load pattern,the amplitudes of the speed signal components f_(r),2f_(r) and 4f_(r) are linear with the misalignment.In addition,under the load pattern,the amplitudes of the speed signal components f_(r),2f_(r) and 4f_(r) have a linear relationship with the load.However,the diagnosis result of the vibration signal does not have the above characteristics.The comparison results verify the robustness and reliability of the speed signal and SVD-HT method.The method presented in this paper provides a novel way for misalignment fault diagnosis.

Motor Driving Leg Design for Bionic Crab-like Robot

The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.

LMI Approach to Robust H_∞/H_2 Controller Design with Regional Poles Constraint of a Pump-Motor System

The time domain guideposts requirements of a pump-motor system is transfered into a series of constraints which express the robust performance upper bound and regional poles limits of the closed loop system. Then the servo system control problem is transferred into the problem of robust performance optimizing under regional poles constrains described by linear matrix inequality （LMI）. These LMIs are easy to solve through the Matlab LMI-toolbox. Simulations indicate that the controller has excellent dynamic, static and disturbance rejection performance, and the control system is robust and has perfect H2 performance to the bounded external torque disturbance.

A Parameter Varying PD Control for Fuzzy Servo Mechanism

This paper presents the formulation of novel implementation method based on parameter varying PD controller for fuzzy servo controllers. This formulation uses the approximation of fuzzy nonlinear function including error and error derivation in operation point. Obtained fuzzy control law has been employed to control angular position of servo using digital control technique applied to a typical microcontroller like AVR. The performance and robustness of modified fuzzy controller in comparison with PID controller evaluated in no load, applied external disturbance with different magnitude conditions has been studied. The simulation results showed that the proposed fuzzy controller has a considerable advantage in rise time, settling time and overshoot respect to PID controller when the servo system encounters with nonlinear features like saturation and friction.

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.

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。

Novel AC Servo Rotating and Linear Composite Driving Device for Plastic Forming Equipment

The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.