DYNAMICS OF PNEUMATIC DRIVE. LECTURE CYCLE. OPTIMIZATION METHODS FOR SERVO PNEUMATIC DRIVES

Abstract

The paper considers the main problems of optimal design associated with the choice of optimal parameters that affect both the static and dynamic characteristics of the pneumatic servo drives – control and actuator mechanisms. The possibility of using one decisive criterion (objective function) is shown, which provides the determination of optimal parameters of a pneumatic actuator with forward and rotational movement of the output link, as well as its application in the synthesis of a servo pneumatic cylinder. To calculate the parameters of the servo pneumatic actuator that are close to optimal, a two-criteria LPt-search was applied. It is shown and the corresponding conclusion is made that the proposed objective function can be used in the synthesis of tracking pneumatic/hydraulic drives with forward and rotational motion of the output link. In addition, the objective function for a drive with an energy source is given. The choice of optimal values of the parameters of the digital PID controller to eliminate self-oscillation in systems, as well as optimization of the type of transients of the tracking pneumatic drive is considered. The reason for the study was the problem of the occurrence of self-oscillations in pneumatic systems when using friction models that are closest to real ones. The transition from an analog (continuous) system to a digital (discrete) one is shown and performed, for which it is necessary to determine the sampling period. The paper specifies the main methods for determining the sampling period and shows the disadvantages of these methods. Its described of the criteria definition allowing to choose the optimum parameters of the actuator piston seal. As criteria, it is proposed to use of the actuator’s volume efficiency hо , characterizing the degree of tightness and operating conditions, and hydromechanical hгм efficiency of the actuator, taking into account energy losses due to hydraulic resistance in the channels and friction in it. There are given the calculated dependences for hо and hгм. The scientific novelty of the results presented in the work is that the problem of structural (static) and dynamic optimization of the design of a servo pneumatic device has been solved. A distinctive feature of the above methods for selecting the optimal parameters of a servo pneumatic device is that they are used not at the final stage of development, but at the design stage of a newly developed product, which saves money, time and costs for conducting expensive tests. This work is based and is implemented as a course of lectures of the course “Dynamics of Pneumatic drive”, is red by the author at the Bauman Moscow State Technical University at the Department of “Hydromechanics, Hydraulic Machines and Hydropneumoautomatics” (E10), as part of the preparation of masters in the specialty 05.04.13 – Hydraulic machines and hydropneumatic drives.