针对二阶过阻尼系统传递函数的参数辨识问题，提出一种根据二阶过阻尼系统阶跃响应估计系统传递函数未知参数的新方法。该方法首先求解出二阶过阻尼系统的阶跃响应表达式，然后定义模型输出与观测数据的差值作为代价函数，将参数估计问题转换为非线性最小二乘问题。通过采用Levenberg-Marquarat算法极小化代价函数，估计出系统未知参数。为确定参数估计的初值，给出采用两点法的参数初值估计方法。仿真结果表明，在含有观测噪声的情况下，提出的方法能有效解决过阻尼二阶系统未知参数的估计问题。%Aiming at the problem of parameter identification for transfer function of two order over damping system, a novel method for estimating unknown parameters in transfer function of the second order over-damped system in accordance with its step response is proposed. With this method, firstly, the expression of the step response of the second order over-damped system is solved, then defining the difference between the model output and observed data as the cost function, the issue of parameter estimation is converted into a nonlinear least square topic. The cost function is minimized through using Levenberg-Marquarat ( L-M) algorithm, to estimate unknown parameters of the system. In order to determine that initial value for parameter estimation, the estimation method of initial value two-point method is given. The results of simulation demonstrate that the method proposed can effectively solve the problem for unknown parameter estimation of such system under observation noises exist.
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