Corresponding author: Khubeev Mars K., D. Sc., Professor, Perm National Research Polytechnic University, Perm, 614000, Russian Federation
e-mail: atp@pstu.ru

Accepted on August 07, 2017

Proportional-integral (PI) controllers are used for continuous control of technological processes' parameters. Algorithms of Pi-controllers have not undergone fundamental changes over the past decade. Manufacturers do not propose controllers that exceed the standard Pi-controller on several key technical characteristics, which include expense of energy and resources, ac­curacy of control and stability margin. Therefore, this article offers resource-efficient Pi-controller. Its use allows to achieve the following objectives: to save energy and resources, to improve automatic control accuracy and to increase the stability margin. A universal energy-efficient PI-controller is put as a basis of this design. Manufacturing tolerances are used to improve its technical characteristics. Situational approach is applied in solving the problem. Computational experiments were carried out for the seven known models of objects of control with the transport delay to assess the effectiveness. In the linear case the superiority of resource-efficient PI-controller compared with energy- efficient PI-controller is characterized by the following results:
— the summary changing of the output of controller (modulo) decreases on average 1,75 times. This helps to save energy and resources of actuator;
— the error of maximum control is reduced by an average of 1,2 times, thereby increasing the quality of products;
— an average operation time of the actuator is decreased by an average of 1,3 times. This ensures resources savings of the actuator.
The following fact indicates the increase of stability margin: if the coefficients of transmission of control objects increased to values when the automatic control system with PI-controller is at the limit of stability, then continuous oscillations are observed in the automatic control system with PI-controller. Herewith an acceptable quality of control is realized in the automatic control system with a resource-efficient PI-controller, since the maximum control error is less in 5 times. The benefits of resource-efficient PI-controller are preserved in a variety of operating conditions — in the presence of nonlinear elements and the various controller setting. The presented results confirm the high efficiency of resource-efficient PI-controller compared with both PI-controller and energy-efficient PI-controller. Comprehensive solution of improvement problem of the basic technical characteristics of the PI-controller determines the practical value of the work. Companies of chemical and related industries are interested in the use of controllers to enhance the effectiveness of automatic control systems.
Keywords: controller, tolerance, algorithm, object, resource-efficient, accuracy, stability, transfer function, transport delay, actuator