A New Adaptive Synergetic Control Design for Single Link Robot Arm Actuated by Pneumatic Muscles

This paper suggests a new control design based on the concept of Synergetic Control theory for controlling a one-link robot arm actuated by Pneumatic artificial muscles (PAMs) in opposing bicep/tricep positions. The synergetic control design is first established based on known system parameters. However, in real PAM-actuated systems, the uncertainties are inherited features in their parameters and hence an adaptive synergetic control algorithm is proposed and synthesized for a PAM-actuated robot arm subjected to perturbation in its parameters. The adaptive synergetic laws are developed to estimate the uncertainties and to guarantee the asymptotic stability of the adaptive synergetic controlled PAM-actuated system. The work has also presented an improvement in the performance of proposed synergetic controllers (classical and adaptive) by applying a modern optimization technique based on Particle Swarm Optimization (PSO) to tune their design parameters towards optimal dynamic performance. The effectiveness of the proposed classical and adaptive synergetic controllers has been verified via computer simulation and it has been shown that the adaptive controller could cope with uncertainties and keep the controlled system stable. The proposed optimal Adaptive Synergetic Controller (ASC) has been validated with a previous adaptive controller with the same robot structure and actuation, and it has been shown that the optimal ASC outperforms its opponent in terms of tracking speed and error.

SYNERGETIC APPROACH TO THE STUDY OF CONTROL SYSTEMS

The paper considers a new direction of scientific research - "synergetics". The key provisions and its development as a science are considered. The focus is on open feedback systems as objects of research. The properties of these systems - openness, nonlinearity, dissipation and multidimensionality, allow the use of a synergistic approach in the study. Due to new trends in information technology in recent years, interest in the new architecture of Software Defined Networks has grown. A programmable controller is used as a control mechanism for SDN networks. The connection between the logical controller and the physical network is made using the OpenFlow protocol. The graph of the network topology is presented as a set of key parameters that come to the controller. From the set of parameters, the key ones used in the study are selected. The dynamics of the ratio of key parameters under the condition of optimizing the network infrastructure is studied. The dynamics of the network corresponding to the stability condition is investigated by the methods of synergetic control theory. SDN network control is formed by methods based on the principle of self-organization of nonlinear systems. As a result, synergetic control is synthesized to increase the resistance of the control system to destructive influences. Based on the selected dynamic invariant, the possibility of providing the selection of the parameter of the SDN network management system for the transition to a controlled state is shown.

TEMPERATURE MODE MANAGEMENT OF CHEMICAL REACTOR

A chemical reactor is one of the common apparatuses in chemical industry. Despite a large number of the works related to automation and control of chemical reactors, the problem of synthesizing control systems that provide the maintenance of optimal modes of their operation remains practically unsolved. This is related to the principal feature of chemical reactors as controlled objects, namely, manifold, non-linearity, and multi-coupling. An outcome from this situation is to develop a physical theory of control, in particular synergetic control theory. The problem of analytical synthesis of nonlinear control law of the chemical reactor temperature regime has been solved. We use the methods of synergetic control theory, simulation methods and methods of computational experiment. The paper deals with continuous stirred tank reactor equipped with a mechanical stirrer and cooling jacket. The reactor operates in the polytropic mode. The multistep series-parallel exothermic process is carried out in the reactor. The objective of chemical reactor operation is to obtain the key product of specified concentration. Using the analytical design method of aggregated regulators, a non-linear control algorithm was synthesized, which solves the problem of stabilization of reaction mixture temperature in the apparatus under the action of disturbances on the object. Computer simulation of the object–regulator isolated system showed such properties of synthesized control system as the disturbance invariance, covariance to the given actions, and asymptotic stability.

THE CONTROL ALGORITHM FOR CONCENTRATION OF THE TARGET PRODUCT IN THE CHEMICAL REACTOR

A chemicalreactor is one of the common apparatuses in chemical industry. Despite a large number of theworks related to automation and control of chemical reactors, the problem of synthesizing controlsystems that provide the maintenance of optimal modes of their operation remains practically unsolved.This is related to the principal feature of chemical reactors as controlled objects, namely,manifold, non-linearity, and multi-coupling. An outcome from this situation is to develop a physicaltheory of control, in particular synergetic control theory. The problem of analytical synthesis of nonlinear control law for the concentration of the target component in a chemical reactor has been solved.We use the methods of synergetic control theory, simulation methodsand methods of computational experiment. The paper deals with continuous stirred tank reactor equipped with a mechanicalstirrer and cooling jacket. The reactor operates in the polytropic mode. The multistep series-parallelexothermic process is carried out in the reactor. The objective of chemical reactor operationis to obtain the key product of specified concentration.

Synthesis of the cascade control system of the thermal regime of a technological object by the methods of synergetic control theory

The paper considers technological control objects whose physical properties, state of aggregation and composition are changed by hydromechanical, physical and chemical effects on the flows of initial substances. The main feature of such objects is their multi-dimensionality, nonlinearity, multiconnectivity, and parametric uncertainty of the mathematical model at the design stage. One of such objects is the chemical reactor with the thermal regime predominantly controlled by single-loop or cascade automatic control systems based on linear algorithms. The main disadvantage of such systems is the problem of maintaining robustness, i.e. stability and control quality under the action of parametric disturbances. In our opinion, the method of analytical design of aggregated regulators (ADAR), developed within the framework of the synergetic control theory, is promising in this sense. The research uses methods of system analysis of technological processes as control objects, methods of the automatic control theory and analytical synthesis of control algorithms based on the synergetic control theory and computer simulation methods. Using the ADAR method, we have solved the problem of algorithmic synthesis of the cascade-coupled control system of the thermal regime of a technological object (chemical reactor) in the nonlinear formulation applying a nonlinear mathematical model of the object. Computer simulation methods have proved the functionality of the «object – control subsystem» complex: system stability, covariance with the set point. It is shown that in the systems controlling thermal processes of the considered type, the heat transfer coefficient parametric uncertainty can lead to an excessive value of the static error, which means that the algorithmic structure of the automatic control system has to be improved. To ensure full robustness of the automatic control system, it is recommended to make the system’s algorithmic structure more complex by introducing an astatic component into the control law and correcting the algorithm tuning parameters.

ROBUST CONCENTRATION CONTROL OF TARGET PRODUCT IN CHEMICAL REACTOR

A liquid-phase continuous stirred tank reactor equipped with a mechanical stirrer and cooling jacket is considered as a control object. The reactor operates in the polytropic mode. The multistep series-parallel exothermic process is carried out in the reactor. The objective of chemical reactor operation is to obtain the key product of specified concentration. The paper deals with analytical synthesis of automatic concentration control system of target product which provides invariance, covariance to the given actions, asymptotic stability and robustness under the action of uncontrollable parametric and signal disturbances. The astatic control law obtained using the synergetic control theory is proposed. Using the method of analytical design of aggregated regulators (ADAR) for a given invariant manifold, a non-linear control algorithm with an integral part was synthesized which solves the problem of stabilization of the concentration of target component on the exit of the reactor at the given value under the action of disturbances on the object. Algorithmic synthesis of the control law is carried out using a non-linear mathematical model of the object without the use of the linearization procedure. As a result of simulation it was found that the closed-loop control system has no static control error under the action of uncontrollable parametric and signal disturbances on the object, changes in the set points and initial deviation of the state variables from the static values. Consequently, the proposed non-linear concentration control algorithm has the property of robustness. The obtained results indicate the effectiveness of the ADAR method and the prospects of the synergetic control theory for solving problems of algorithmic synthesis of control systems of non-linear, multi-dimensional and multi-connected technological objects. The integration of the synthesized control law of chemical reactor at the design stage will allow implementing flexible cybernetically organized chemical-technological systems.