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微纳卫星微推力器的性能测试,要求在诊断稳态推力和冲量的同时测量动态推力,为此开展动态推力测试方法研究。根据扭摆式台架的二阶质量-弹簧-阻尼系统模型及特点,提出通过静、动态砝码标定,进行扭摆台架的转动惯量、阻尼常数和弹簧系数等参数辨识。利用干涉式激光位移计实现对微小位移的高精度和高频响测量,系统的测量精度约为10nm,测试带宽500k Hz。建立了探测器的记录光强与微位移间的数学模型,获取台架微位移,通过对微位移进行一次、二次求导获得台架的速度和加速度信息,根据台架运动方程,实现动态推力测量。误差分析表明,稳态推力测试的最大绝对误差小于0.5mN,动态推力测试的最大误差约为0.58mN。利用落压式工作的微型冷气推力器开展验证试验,结果表明该测试方法能够实现动态推力测量要求,响应频率为50Hz。
The performance test of micro-nano satellite micro thrusters requires that the dynamic thrust be measured while diagnosing the steady-state thrust and impulse. Therefore, the dynamic thrust test method is studied. According to the second - order mass - spring - damping system model of torsion pedestal and its characteristics, this paper proposed the parameters identification of moment of inertia, damping constant and spring coefficient of the torsion pendulum by static and dynamic weight calibration. The use of interferometric laser displacement meter to achieve high precision and high frequency response of small displacement measurement, the system measurement accuracy of about 10nm, the test bandwidth of 500k Hz. The mathematical model between the light intensity and the micro-displacement of the detector is set up to obtain the micro-displacement of the gantry. The velocity and acceleration information of the gantry are acquired through the first derivative and the second derivative of the micro-displacement. According to the kinematic equation of the gantry, the dynamic Thrust measurement. Error analysis shows that the maximum absolute error of steady-state thrust test is less than 0.5mN and the maximum error of dynamic thrust test is about 0.58mN. The use of pressure-type micro-air-conditioning thrusters to carry out verification tests, the results show that the test method to achieve dynamic thrust measurement requirements, the response frequency of 50Hz.