Method of identifying transfer function of a pneumatic/hydro apparatus

A large number of modern industrial systems of control by actuators is composed of elements of pneumatic/hydraulic automatics. In the synthesis of such systems, however, the challenge is to study their dynamic properties and stability. These quality systems are influenced by their constituent components, in particular pneumatic/ hydro apparatus, because the elements after connection with each other can form an unstable system, and/or, on the contrary, a sustainable system may contain unstable elements. To analyze it, it is needed to check the stability of any component included in the projected system. On this basis, the aim of this work was to establish unambiguous relationships obtained by experimental frequency characteristics of pneumatic/ hydro apparatus and type of transfer functions that allow to analyze the stability of the system that uses it. The article presents the method of obtaining the experimental amplitude and phase frequency characteristics of the pneumatic/ hydro apparatus, given the basic relationships required to build them. The issue of identification of transfer functions on the example of selected number of pneumoapparatus, obtained experimentally, the amplitude and phase frequency characteristics are considered. For each of these pneumoapparatus were obtained constant coefficients of the transfer function. The estimation of the dynamic properties of these pneumoapparatus was made. As evaluation criteria were adopted: the transient time and the maximum dynamic error. There was performed assessment of the stability of the system consisting of a pneumatic cylinder with sensor feedback on the status of the stock jointly with each of the considered pneumoapparatus. To study the stability of the system the linearized mathematical model was composed for this system. For the created model of the system was built amplitude and phase frequency characteristics in logarithmic scale (LAH and LPH), which were found reserves of amplitude and phase of the whole system. According to the results of the work performed, conclusions were drawn.

transfer function, identification, characteristics, frequency, pneumoapparatus