Absolute stability for low order ADMIRE model with rate limited actuator

In this paper absolute stability for a longitudinal low order ADMIRE model with rate limited actuator is investigated using a frequency Popov-type criterion. The analysis is performed in the frame of the Lurie problem with rate limited actuator representing the nonlinear part and the linearized low order ADMIRE system expressing the linear part. The closed loop transfer function has one simple pole in the origin and the mentioned criterion (for the parameter ξ = 1) is used in this critical case. Numerically, when the frequency domain inequality of the criterion is analysed, a very small coefficient of the transfer function denominator is approximated to be zero, so the critical case considered can have the characteristic of two poles in the origin.