Abstract
In the previous report, we showed a simple method to identify the approximate transfer function of an instrument as a standard 2nd order system by using self-excited oscillation analysis provided that the output detector's delay in the self-excited oscillation system is negligible.
This paper discusses the effects of output detector's delay on the identified results, and shows a method to identify its approximate transfer function on the condition that the delay is not negligible. The experiments on an electro-hydraulic servo-valve are conducted by means of a self-excited oscillation system in which the flow-rate detector's delay is composed of an analogue electric circuit as a 1st order delay system. Consequently, it is confirmed that the identified frequency transfer functions of an electrohydraulic servo-valve G (jω) almost coincide with its measured frequency characteristics within the frequency region where∠G (jω) is more than-75°, even though the ratio of flow-rate detector's time constant to an equivalent servo-valve's time constant is more than 0.36.
