针对一般无源电阻发生器精度低、稳定性差等缺点,提出一种基于广度优先搜索算法的高精度无源电阻发生器。首先,分析影响无源电阻器输出精度的硬件影响因素,模拟各误差叠加作用下的实际输出电阻值,建立电阻组合与其实际输出值的定量关系方程,并通过系统校准确定方程初始参数;然后,采用广度优先搜索算法求解方程,获得输出值最接近设定电阻值的最优电阻组合,实现高精度无源电阻输出。实验结果表明:此方法在实现1.0Ω~20kΩ的输出范围、0.1n(1kΩ以内)分辨力的技术指标下,电阻器输出相对误差〈2.4%,系统响应时间优于500ms。能够满足仪表调校场合对无源电阻器的输出精度要求,且系统具有一定的稳定性。
To overcome the problems of low precision and weak stability of general passive resistance generators, a high-precision passive resistance generator based on breadth-first search (BFS) algorithm is presented. Firstly, the hardware affecting the output accuracy of passive resistance generator is analyzed, the actual output resistance under different error superposition is simulated, a quantitative relation equation between the resistor combination and its output resistance value is established and the initial parameter of the equation is determined through system calibration. And then, use the BFS algorithm to solve the equation to get the optimal resistor combination whose output resistance value is closest to the preset resistance value to realize the high-precision passive resistance output. Experimental results show that, in an output range of 1.012-20.0kΩ and resolution of 0.1Ω(within 1 kΩ), the relative error of resistor output is less than 2.4% and the system response time is less than 500 ms, showing that the resistance generator can meet the requirements for precision in instrument calibration and has certain stability.