基于动压反馈的气动负载模拟器控制策略研究

发布时间：2018-04-22 07:39

本文选题：气动力伺服系统频率特性 + 间隙机构　；参考：《哈尔滨工业大学》2012年硕士论文

【摘要】：气动负载模拟器作为近几年新起的负载模拟器，是一种典型的被动式力伺服系统。气动系统作为加载部分其主要目的为模拟飞行器中舵面机构在摆动时所受的空气力矩。舵机的主动运动往往会对气动系统产生位置干扰，进而引起多余力，选择气动系统作为加载装置可以大幅降低多余力的影响，但是由于气动系统的非线性，使的气动力控制伺服系统较其他形式加载装置频率特性差，所以减少力控制信号的相位滞后提高系统动态特性成为本文主要的工作。首先建立气动系统数学模型，采用机理建模的方式得到气动系统的传递函数，分析得出系统达不到预期控制目标的主要原因是加载系统在舵机系统的强干扰下实行加载所导致。由于气体的可压缩性，使干扰作用在实际中体现在舵机运动导致的两腔压力变化。考虑到速度补偿不容易实现的特点，提出采用动压反馈，补偿位置造成的干扰，根据补偿的力与位置变化产生的力相等推导出动压反馈的传递函数。在仿真和实验中主要调节动压反馈系数的大小。建立伺服电机的数学模型，合理设置参数。通过matlab对电机动态特性进行仿真。通过Amesim建立了气动负载模拟器的实际模型，分别采用PID和PID+动压反馈的控制方法，得出动压反馈优于PID调节。另外分析了影响系统动态特性的其他因素包括比例阀和气源压力的选择。采用Adams对负载模拟器机械结构进行动力学分析，分析机械结构间隙对加载力曲线的影响，得到不同间隙下的摇杆位移、速度和加速度曲线，得到合理间隙值，为实验环节做下准备。同时针对伺服电机在低频时动态特性不足，设计出惯量轮，借此在实验中提升电机动态特性。另外合理选择整个实验台的底座，采用较大的底座惯量，提高整个实验台的刚性。搭建气动负载模拟器特性实验台，实验以Matlab中xpc-target工具建立软件系统，采用上下位机的形式控制板卡进行数据采集与实时控制。采用PID和PID+动压反馈两种控制方法。同时验证了机械结构优化设计对力曲线的影响，，测试结果表明实验曲线与仿真曲线基本一致。
[Abstract]:As a new load simulator in recent years, pneumatic load simulator is a typical passive force servo system. As the loading part, the aerodynamic system is designed to simulate the air torque of the rudder mechanism in the aircraft when it is swinging. The active motion of the steering gear often produces the position interference to the pneumatic system, and then causes the redundant force. Choosing the pneumatic system as the loading device can greatly reduce the influence of the redundant force, but because of the nonlinearity of the pneumatic system, The frequency characteristic of the pneumatic control servo system is worse than that of other loading devices, so reducing the phase lag of the force control signal and improving the dynamic characteristics of the system become the main work in this paper. Firstly, the mathematical model of pneumatic system is established, and the transfer function of pneumatic system is obtained by mechanism modeling. It is concluded that the main reason that the system can not achieve the expected control goal is the loading of the loading system under the strong disturbance of the steering gear system. Because of the compressibility of the gas, the interference is reflected in the pressure change of the two cavities caused by the motion of the steering gear. Considering the fact that velocity compensation is not easy to be realized, it is proposed that dynamic pressure feedback is used to compensate the interference caused by position, and the transfer function of dynamic pressure feedback is deduced according to the force produced by the compensated force and the change of position. The dynamic pressure feedback coefficient is mainly regulated in simulation and experiment. The mathematical model of servo motor is established and the parameters are set up reasonably. The dynamic characteristics of the motor are simulated by matlab. The actual model of pneumatic load simulator is established by Amesim. The control methods of PID and PID dynamic pressure feedback are adopted respectively. The result shows that the response pressure feedback is better than the PID regulation. In addition, other factors affecting the dynamic characteristics of the system are analyzed, including the selection of proportional valve and air source pressure. The dynamic analysis of the mechanical structure of the load simulator is carried out by using Adams, and the influence of the gap of the mechanical structure on the loading force curve is analyzed. The displacement, velocity and acceleration curves of the rocker rod under different gaps are obtained, and the reasonable gap values are obtained. Prepare for the experiment. At the same time, the inertia wheel is designed to improve the dynamic characteristics of the servo motor in the experiment. In addition, the base of the whole test platform is reasonably selected, and the rigidity of the whole test platform is improved by adopting the larger inertia of the base. The characteristic test bench of pneumatic load simulator was built. The software system was established by xpc-target tool in Matlab, and the data acquisition and real time control were carried out by the form of upper and lower computer control board. PID and PID dynamic pressure feedback control methods are adopted. At the same time, the effect of mechanical structure optimization design on the force curve is verified. The test results show that the experimental curve is basically consistent with the simulation curve.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH138;V216.8

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