Electro-hydraulic Servo Motor Research Articles

Friction Feedforward Compensation Composite Control of Continuous Rotary Motor with Sliding Mode Variable Structure Based on an Improved Power Reaching Law

In order to meet the accuracy requirements and tracking performance of continuous rotary electro-hydraulic servo motor system under nonlinear uncertainty and strong disturbance factors, the sliding mode variable structure composite control strategy based on an improved power reaching law is proposed. Based on the principle of valve-controlled hydraulic motor, the state space model of the motor system is established, and a continuous friction model is adopted. Then, the genetic algorithm is used for parameter identification to determine the friction feedforward compensation scheme. In addition, an improved power reaching law is designed, which can adaptively adjust the system chattering according to the system state. The simulation results show that the sliding mode variable structure composite controller with the friction feedforward compensation can achieve a system frequency of 15 Hz, and tracking accuracy and response speed meet the double-decade index requirements, which improve the performance of continuous rotary electro-hydraulic servo motor.

Research on robust control of continuous rotary electro-hydraulic servo motor based on AdaBoost prediction

A robust control strategy based on Adaboost prediction was proposed for the effects of dynamic uncertainty, parameter perturbation and nonlinear factors such as friction and leakage on the robustness and low-speed performance of the electro-hydraulic servo system. Based on the establishment of the Pol-Ind friction model, according to the mathematical model of the continuous rotary electro-hydraulic servo motor, the structural uncertainty model of the system under parameter perturbation and external perturbation and the generalized state equation of the system are established. The robust controller is designed according to the [Formula: see text] control theory. The system feedback mechanism is designed by using the AdaBoost based on the RBF neural network algorithm. The real-time input and output of the system are used as the training sample set for repeated training, and the multiple weak neural network predictors obtained by training are used to form a strong predictor to calculate the forecast output and error of the electro-hydraulic servo system, and the robust controller was used for real-time control. Simulation and experiment show that: compared with the wavelet neural network control, the robust controller based on AdaBoost prediction has a good tracking performance to the slope signal with an input signal of 0.001°/s, and has a high response speed to sinusoidal signal. Under the condition of satisfying the requirement of double 10 index, the maximum response frequency reaches 15 Hz. It can effectively improve the low-speed performance and anti-interference ability of the electro-hydraulic servo system, greatly improve the robustness of the system and expand the frequency band of the system.

Research on the Finite Time Compound Control of Continuous Rotary Motor Electro-Hydraulic Servo System

Aiming at the influence of friction, leakage, noise and other nonlinear factors on the performance of the electro-hydraulic servo system of a continuous rotary motor, a finite-time composite controller for the aforementioned servo system is proposed. First, a mathematical model of the electro-hydraulic servo system was analyzed, and the input and output angle data of the motor were collected for system identification. Subsequently, the ARMAX identification model of the continuous rotary motor system was obtained. Then, according to the observed advantages, namely faster capability of the finite-time controller (FTC) to converge the system, and ability of the finite-time observer to reduce the steady-state error of the system, the finite-time controller and finite-time state observer of a continuous rotary electro-hydraulic servo motor were respectively designed. Finally, comparison with PID control simulation shows that the compound controller could effectively improve the control accuracy and performance of the system.

Research on Model-Free Adaptive Control of Electro-Hydraulic Servo System of Continuous Rotary Motor

The model-free adaptive controller (MFAC) for continuous rotary electro-hydraulic servo motor was proposed to deal with uncertainties such as friction, leakage and noise. The model of electro-hydraulic servo motor system was replaced by universal model, and the structure adaptive control and parameter adaptive control were combined, and MFAC controller of the motor system was designed by using the input and output data of the system to realize the low speed and tracking control of the motor system. It is proved by simulation and experiment that MFAC controller effectively improves the low-speed stability and anti-interference ability of electro-hydraulic servo system compared with traditional PID control, and MFAC controller widens the frequency response of the system and realizes the precise control of continuous rotary motor servo system.

Modeling, simulation and controller design for a typical bent axis electrohydraulic servo motor

Bent axis electrohydraulic servo motors are one of the Electrohydraulic Servo Motors (EHSMs) family which are used in high frequency, speed, and precision applications such as aerospace applications as well as many military weapon system applications. Therefore, it is essential to understand how such motors affect the whole performance of the system which makes modeling of these motors is an important task to be achieved. Once an accurate model is obtained, an optimum controller can be applied. This paper introduces detailed mathematical modeling of a typical bent axis (EHSM). MATLAB SIMULINK package is used to simulate and control such (EHSM) using PID controller. The PID controller gains were tuned using PD-PI controller to obtain the precision response for the (EHSM). The validity of mathematical modeling was reviewed through some practical experiments.

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.

Investigating the Dynamic response of Electrohydraulic Servo Motor

The dynamic response of electro-hydraulic servo systems (EHSS) is complex and its characteristics are highly nonlinear. These nonlinear features need to be discussed and modeled as electro-hydraulic servo systems are now the main muscle a lot of applications that need precise and fast control. Therefore, a detailed and precise mathematical model needs to be deducted to get an effective controller design procedure. The goal of this work is to develop a mathematical model, a simulated model using the Simulink program and control method using an effective controller for Electro-hydraulic servo motor (EHSM). These concepts will allow study-ing, analysis and control of the dynamic characteristics of EHSM velocity and position. To demonstrate the effectiveness of this analysis the experimental work has been done via Electro-hydraulic servo mechanism EHS 160, DAQ NI 6008 and Simulink program.

Research on the Pressure Impact Characteristic of Continuous Rotary Electro-Hydraulic Servo Motor

In order to reduce the pressure impact of continuous rotary electro-hydraulic servo motor, ensure the smooth pressure transition during the motor commutation, and improve the control accuracy, a kind of pre-compression chamber structure was proposed. The fluid domain models with pre-compressed chamber structure were established. The decompression process of the motor in long radius arc region and boosting process in short radius arc region were simulated and analyzed by FLUENT software. Through comparing and analyzing pressure distribution, outlet flow rate, and cross-section flow rate of fluid models, basing on a drosophila optimization algorithm, the optimum structure size of the pre-compression chamber of the motor is obtained. The results show that the optimal side length of the pre-compression chamber is 10 mm in the compression process, while the optimal side length is 26.273 mm in the decompression process. The pre-compression chamber structure can effectively reduce the pressure impact of the continuous rotary electro-hydraulic servo motor.

PID–PFC control of continuous rotary electro‐hydraulic servo motor applied to flight simulator

Due to the uncertainties caused by high non-linearity, friction, leakage and other external factors existing in the flight simulator with continuous rotary electro-hydraulic servo motor and the traditional control strategies discontenting with the high-performance requirements, the mathematical model of continuous rotary electro-hydraulic position servo system is established and the compound control theory combining proportional-integral-derivative (PID) and the predictive function control (PFC) method is proposed. In order to enable the servo system to estimate the influence of uncertainties and correct it by repeating online optimisation continuously, PID–PFC compound controller basing on the structure of internal model control is designed and then applied to continuous rotary electro hydraulic servo system. The simulation results show that compared with the traditional PID, PFC controller, PID–PFC compound control can effectively inhibit the interferences of the electro-hydraulic servo system, and greatly improve the response speed and tracking performances and expanding the system frequency band width. The accurate control of motor's position can be realised by applying PID–PFC compound control, which can make the servo system has stronger robustness.

Research on the leakage of continuous rotary electro-hydraulic servo motor based on fluid structure interaction analysis

PurposeInternal leakage is one of the key factors that influence the super-low speed performance of continuous rotary electro-hydraulic servo motor. Therefore, this paper aims to study the change rule of internal leakage for improving the low speed performance of motor.Design/methodology/approachThe mathematical models of internal leakage of continuous rotary electro-hydraulic servo motor were established, and according to the working principle of the motor, the 3D models of internal leakage location were established. Simulation analysis was implemented on the continuous rotary electro-hydraulic servo motor by the finite element analysis software ANSYS based on the fluid-structure interaction theory.FindingsThe results show the deformation of motor’s key parts and the changing rule of internal leakage. The effect of the leakage to the low speed performance of electro-hydraulic servo motor was analyzed, and at the same time, the motor’s leakage experiment was also conducted to verify the validity of simulation results.Originality/valueThis paper lays the foundation for improving the low speed performance of motor.

Research on the Adaptive Zero Phase Error Tracking and Proportion Composite Controller of Continuous Rotary Electro-Hydraulic Servo Motor

According to the poor tracking accuracy of periodic signals for continuous rotary electro-hydraulic servo motor, the mathematic model of the electro-hydraulic position servo system of the continuous rotary motor was established, a composite control strategy combining with proportion controller and adaptive zero phase error tracking controller was designed. The working principle of composite strategy was given, and the composite strategy was verified on Co-simulation of MATLAB and AMESim platform. The simulation result shows that the amplitude attenuation and phase delay of the tracking curve which excitated by the sinusoidal signal 0.5degree and 10Hz for continuous rotary motor is less than 1.2% and 1.08°respectively, and the efficiency of the composite controller is verified through simulation.

Research on the Motor Friction Model of Electro-Hydraulic Servo System

In order to improve the performance of the electro-hydraulic servo system, considering the special structure of servo motor, nonlinear model of the servo motor was established in time domain. Several friction models commonly used in project were introduced and applied to the simulation analysis of servo motor with friction torque. The simulation curves show the relationship between driving torque, friction torque, angular velocity and angular displacement. The result confirms the influence of the different friction torque model on the performance of motor, and the LuGre friction model is identified which is fit for the friction torque compensation. This study lays the foundation for the friction torque compensation of electro-hydraulic servo motor.

Research on the Friction Mechanism and Minimum Steady Speed of Electro-Hydraulic Servo Motor

The super low speed performance of continuous rotary motor is the key performance, many factors influence the super low speed performance, such as friction and leakage characteristics of the motor, pressure impact, pressure fluctuation of the oil source, resolution and the dead zone of the servo valve. This paper study the low speed movement mechanism, by analyzing the friction mechanism model of motor, and analyze the low-speed process the system to explore the factors that affect the low-speed performance of system, and determine the lowest steady speed of motor.

Continuous Rotary Motor Electro-Hydraulic Servo System Based on the Zero Phase Error Tracking Controller

In order to suppress the friction and leakage interference of continuous rotary electro-hydraulic servo motor, make the motor tracking the periodic signals with high accuracy, and improve the high frequency response performance of continuous rotary electro-hydraulic servo motor, this paper established the mathematic model of the electro-hydraulic position servo system of the continuous rotary motor, and adopted the controlling method based on the zero phase error tracking controller to suppress the interference. Through the simulation, the result confirms that the zero phase error tracking control method decreases the tracking error of the system, increases the robust performance of the system and improves the frequency response performance of continuous rotary electro-hydraulic servo motor. This method is simple and feasible.

예측 적응제어 기법을 이용한 전기 유압 모터의 제어에 관한 연구

Electro-hydraulic servo motor is used to a lot of in the field of industrial equipment which requires one of the control functions among pressure, flow, and power output. In this paper, linear discrete reference model of the electro-hydraulic servo motor system are made for 1-step ahead predictive control. The parameters of electro-hydraulic servo motor system are estimated using the recursive least square method. 1-step ahead predictive model output of electro-hydraulic servo motor system corresponded to reference model output in spite of estimated parameters are not meet real parameters. Control performance affections are studied due to the forgetting factors variation.

Buffer Groove Design of Continuous Rotary Electro-Hydraulic Servo Motor Used in Simulator

In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distributing, this paper designed the shape of buffer groove, established the mathematical model of pressure gradient, and analyzed change law of sealed cavity pressure gradient under different dimension of buffer groove. The pressure field distribution of sealed cavity was studied in certain radial and axial gap, and it is validated the dimension of buffer groove is rational, which lays foundation for structure design and experimental research of large displacement servo motor.

Continuous Rotary Motor Electro-Hydraulic Servo System Based on Discrete Sliding Mode Controller

In order to suppress the periodic interference of continuous rotary electro-hydraulic servo motor, make the motor tracking periodic signals more accurate, and improve the influence of friction interference on the performance of continuous rotary electro-hydraulic servo motor, mathematic model of continuous rotary motor electro-hydraulic position servo system was established, and the compound control method based on the discrete sliding mode controller was adopted to suppress the friction interference. Through the simulation, the result confirms that the discrete sliding mode controller decreases the tracking error of the system, increases the system robust performance and improves performance of continuous rotary electro-hydraulic servo motor. This method is simple and feasible.

Pressure Field Analysis of Continuous Rotary Electro-Hydraulic Servo Motor Based on ADINA

In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distribution, based on fluid and solid interaction theory, this paper adopted ADINA to analyze the pressure field distribution of sealed cavity in certain radial and axial gap, the computed model of the motor was established, and the pressure change of sealed cavity under the given dimension of the buffer groove was analyzed. The result shows that the pressure changes stably and buffer groove’s dimension is reasonable, which lays foundation for the structure design and experimental research of large displacement servo motor and improve the low speed performance of continuous rotary electro-hydraulic servo motor.

Structure Optimization for Improving Low Speed Performance of Continuous Rotary Electro-hydraulic Servomotor Based on the Improved Genetic Algorithm

In order to improve the low speed performance of continuous rotary electro-hydraulic servomotor,the flow and pressure characteristics of motor airtight cavity are analyzed considering the changes of flow and pressure and the characteristics of leakage and friction in the course of pressure switch.In view of the complication of solving the problem,an improved genetic algorithm with initial population gradually drifting is introduced to carry out the structure optimization for improving low speed performance.The formula of pre-transitional curve of the stator and its angle range is derived,and the optimum dimension of triangle cushioning groove of the valve plate is also obtained.The analysis result of the simulation and experiment validates that the theory is reasonable and the algorithm is effective.This optimization method avoids premature convergence.Furthermore,by applying the technique of initial population gradually drifting to the improved genetic algorithm,the robust capability of initial value is also improved and the neighbor-function structure is more reasonable.By using the method to design the servomotor,the continuous rotary electro-hydraulic servomotor can track the ultra-low speed ramp signal of 0.001(°)/s and meet the requirement of the tolerance zone of 0.001°.So,this method opens up a new way of solving this kind of problem.

716 電気油圧サーボモータの周波数整形型スライディングモード制御(ロボ・メカIII)

716 電気油圧サーボモータの周波数整形型スライディングモード制御(ロボ・メカIII)