Digital PID controller for pneumatic and hydraulic systems

Abstract

In the development of technological systems with pneumatic or hydraulic drive, the use of automated means for their control is required. At present, automated control tools built with the help of logic controllers are widely used. The logical controller allows to solve a wide variety of tasks with minimal costs, both in terms of cost and time spent for developing the system. So the logic controller ensures the speed of systems with pneumatic or hydraulic drive up to 1 ms or less. With the use of digital automated controls, questions related to the synthesis of PID regulators and the stability of systems with pneumatic / hydraulic drive in the time domain arise. The purpose of this work was the creation and practical implementation of a digital PID controller for controlling the pneumatic / hydraulic system to provide practical recommendations for its use in engineering. The article presents a block diagram of analog and digital control systems with a proportional pneumatic distributor. The implementation of analog and digital PID-controller and optimization of its parameters by an integral criterion is presented. Comparison of analog and digital systems with the PID controller introduced into their composition is made. The quality of these systems is suggested to be estimated in the time domain by the time of the transient process and the maximum dynamic error. Practical recommendations for determining the sampling time of digital systems with a PID controller are given. An example of the developed digital automatic control system for tracking pneumatic drive is shown, its structural diagram, the general view of the control device with the logic controller and the graphic operator interface, which makes it easy to configure the automated control tool and monitor its state. The scientific novelty of the results presented in the article was that the task of investigating the dynamics of a pneumatic / hydraulic distributor with an electric control in the time domain was solved using a mathematical model that included a digital PID controller and a comparison of the results of modeling a digital system with analogue was made, and practical recommendations for determining the sampling time were given.