Research On The Key Technique Of Continuous Rotary Electro-hydraulic Servo Motor Applied To Simulator

Flight Simulator is a set of high-tech equipment with important significance of economic value and national defense. As it is used to reproduce the flying posture of the flying weapon in the laboratory, the simulator's performance indexes directly relate to the fidelity of simulation results. So it is necessary for simulator to have perfect super low speed, high frequency response, wide speed range, high precision. Hydraulic simulators only driven by electro-hydraulic servo motor can avoid lower system stiffness, higher nonlinearity and lower control accuracy caused by transmission mechanism of the indirect driving, at the same time, the perfect performance of the servo motor is also demanded strictly. With the development of modem military techniques in our country, it is demanded that simulator can simulate aerocraft to rotate continuously around its central axis during the course of flying, so hydraulic simulators only driven by swing electro-hydraulic servo motor can not meet the needs, With this background, continuous rotary electro-hydraulic servomotor directly driving simulator and its control system are studied in this paper.After synthesizing a lot of related literatures and reference materials at home and abroad, this paper summarizes the outline of simulator development, introduces current study situation and some key techniques of continuous rotary electro-hydraulic servo motor used in simulator, and analyses the main factors influencing the low speed performance of the motor. This paper also takes a survey of recent situation of electro-hydraulic position servo system and its normal automatic control strategy. Based on all the described materials, the main study content is put forward.It is analysed that this servomotor has realized non-pulsation of rotating speed, flow and theoretic output torque, and in order to decrease the influence of friction, through friction orthogonal experiment, materials of the key parts of continuous rotary electro-hydraulic servo motor is confirmed based on the minimal friction coefficient. The model of inner leakage is established and the influence to the low speed performance of the motor is analyzed through simulation.This paper carries out structure improved design of large displacement continuous rotary electro-hydraulic servo motor. Based on decreasing inner leakage, this paper also designs a new type top structure of the vane in order to reduce the fact pressure angle between the vane and the inner surface of the stator, and adopts the end oil distributing with valve plate and cover integrative structure, which can decrease the distortion and the leakage, and improve the low speed performance.In order to improve the stationary of the low speed and avoid the pressure impact in the sealed cavity during the oil distributing, this paper designs the shape of buffer groove, establishes the mathematical model of the pressure gradient, and analyses the change law of the pressure gradient of the sealed cavity under the different dimension of the buffer groove. Based on fluid-structure interaction theory, the inner flow field is analyzed through the finite element analyze, the distribution of pressure field of the sealed cavity is studied in certain radial and axial gap, and validate the rationality of buffer groove's dimension, which lays the foundation for the structure design and experimental research of large displacement servo motor.The mathematical model of continuous rotary motor electro-hydraulic positon servo system is established, the swept sine signal is used as an input signal, the entire circumferential closed-loop parameters identification experiment of the motor is done in every 10 degree based on the structure feature. Through the input and output data sequence collected, parameters of system model is identified by prediction error method based on Gauss-Newton optimization algorithm, the change range of the parameters and frequency characteristics of the system are obtained.For time-varying and non-linear uncertainties of the motor system parameters, based on the design index of electro-hydraulic servo motor, combined with the results of model parameters identification, this paper uses the quantitative feedback theory to design the second freedom of QFT robust controller based on differential feed forward of input signal, simulation results between QFT robust controller based on differential feed forward of input signal with the traditional PID control show that the composite controller improves the system performance obviously.This paper have completed structure design, machining, assembly and testing of large displacement continuous rotary electro-hydraulic servo motor, established experiment platform of system. The hardware interface circuit and the control software are developed which have relatively perfect function.Based on the second freedom of QFT robust controller based on differential feed forward of input signal, many experimental about the low speed performance, the characteristics of positive and negative, step signal, and sine wave have been done under different source oil pressure and output pressure of reducing valve, and the maximal angular velocity, maximal angular acceleration of the motor, as well as the inner leakage have been tested. The experimental results also confirm validity of the theoretic analysis; the system has perfect synthetically performance, and continuous rotary electro-hydraulic servo motor suit simulator's need.