基于跟踪微分器的CMG框架超低速测速方法研究

Research on ultra-low speed measurement for CMG gimbal based on tracking-differentiator

超低转速下,框架的测速精度是影响控制力矩陀螺框架系统控制精度的重要因素。针对超低转速下使用传统一阶后向差分方法计算转速会导致噪声放大的问题,给出了一种基于非线性跟踪微分器的实时速度估计方法,以及该方法基于四阶龙格库塔法的离散表达公式。提出了一种复合的测速策略,解决了直接使用跟踪微分器计算转速的跟踪延迟问题。进行了数值仿真分析和试验验证,仿真结果表明,所提出的测速方法有效降低了传感器输出的量化噪声和测量噪声对速度测量精度的影响;试验测试结果统计表明,相比传统的后向差分法,采用跟踪微分器计算转速,框架速度的波动量减小了67.1%。

At ultra-low speed, the precision of gimbal speed measurement is a key factor which influences the control accuracy of a control moment gyro （CMG） gimbal system. Focusing on the problem of noise amplification brought by conventional first-order backward differentiator when calculating ultra-low speed, a real-time speed estimation method based on a non-linear tracking differentiator and its discrete time expression using the fourth order Runge-Kutta method was proposed. A composite speed measuring method was presented to solve the tracking delay problem when using tracking differentiators directly. Then, thenumerical simulation and experiment were conducted. The simulation results demonstrate that the speed estimation method proposed could reduce the quantization noises brought bytachometers and measurement noises. The experimental results show that by using tracking- differentiators the fluctuation of gimbal speed is reduced by 67. 1 .