一种基于悬臂梁结构的动态推力测量方法

为实现星载微推进器性能评价中的动态推力测量，基于悬臂梁动力学模型，建立了测量系统的传递函数，分析了系统的输入输出特性，根据悬臂梁响应速度快（振动频率高）、动态分量在较小时间区间内接近等幅振荡（阻尼比小）以及高阶振动可视为基频振动噪声的特性，提出了求解稳态位移的末端均值法。该方法通过消除位移响应中的动态分量，得到了误差带较大时的稳态位移时变值，实现了动态推力测量。依据系统稳态位移与推力为线性关系、线性系数为系统增益值这一特性，提出了参数标定方法。搭建了试验平台，标定得到系统响应时间为156ms，通过对比扭摆系统测量结果，悬臂梁测量得到的冲击力与实际推力相对误差为4.064%，结合冲击力本身的测量误差1.383%，最终得到推力测量误差为4.293%。

A measurement method of dynamic thrust based on cantilever beam

To realize dynamic thrust measurement in space borne micro thrusters′ performance assessment, the transfer function of the measurement system was determined based on cantilever′s dynamic model.System input and output characteristics were analyzed, and a terminal mean method for solving the steady state displacement was put forward according to cantilever beams′ characteristics that the response speed is high (vibration frequency is high), the dynamic component is close to constant amplitude oscillation in a small time interval (damping ratio is small), and that the higher order vibration can be regarded as the noise for fundamental frequency vibration. By eliminating the dynamic components in the displacement response, the time variant value of the static displacement was obtained when the error band was large, and thus the dynamic thrust measurement was realized. According to the linear relationship between the thrust magnitude and the steady displacement under the action of step force with the linear coefficient as the system gain value, the parameter calibration method was put forward. An experimental platform was built with response time 156ms by calibration. By comparison with measurement results of torsional balance system, the relative error 4.064% between the impact force on cantilever and the actual thrust was obtained, and the thrust measurement error 4.293% was finally obtained by combination with the measurement error 1.383% of impact force itself.