Taking into account the non-linear, time-varying temperature characteristics of the tunnel kiln, high inertia and some uncertainty of its parameters, it’s difficult to create an accurate mathematical model and get an acceptable set of the controller of the control system. The asynchronous motor actuator of the system, which regulates the amount of gas and air to change the temperature, gives the system first-order a statism. A conventional PID controller does not provide the required quality parameters of temperature control in the entire possible range of changes in the parameters of the controlled object. Thus, the synthesis of an additional fuzzy PID controller is required to ensure the required quality of regulation. Of course, PID control and fuzzy intelligence will provide effective self-tuning of the parameters of controlled PID controllers. A simulation experiment in Matlab shows that fuzzy PID control reduces the time and magnitude of overshoot, effectively increasing the stability of the system by giving it robustness properties.

The paper considers the problem of developing a digital system for an induction motor speed control which has a sensor and a speed regulator to increase accuracy of speed control. Speed control is carried out by a scalar method due to consistent change in the stator frequency and voltage. To obtain the uniformity of the motor overload capability in a given range the control mode is used associated with maintaining uniformity of flux linkage of the motor stator. Induction motor scalar models do not possess high accuracy and their parameters and their parameters can vary over a wide range, which complicates the controller design and achievement of robustness of the speed control system. To eliminate these disadvantages, it is proposed to use a vector model in a rotating coordinate system having subjected it to linearization at different points of the operating mode with the account of the adopted law of frequency control, to ensure robust absolute stability of the system on the basis of application of a graphical method for constructing a modified amplitude-phase characteristic.

The paper considers the system of automatic control of the tunnel kiln temperature conditions. The investigation of a delay influence on the transition process has been carried on. The transfer function of the object under control with interval coefficients taking into account possible effects of the parametric uncertainty has been obtained. A graphical method of representing the obtained results in the form of displaying the modified amplitude-phase characteristics on a complex plane has been applied which obviously demonstrates a robust absolute stability of the system under investigation. The simulation performed in the Matlab environment has proved the correctness of the results obtained.

The paper considers an automatic control system for a small gas turbine engine. The synthesis of a controller providing an increase in the speed of the control system was carried out using the standard procedures of the Matlab system. The transfer function of the control object is obtained with interval coefficients that take into account the possible effects of the uncertainties of the models under study. A graphical method of displaying the obtained results in the form of displaying the fuzzy branches of the root locus on the complex plane is used, which clearly shows the robust absolute stability of the system under study. The superiority of the proposed result over the existing ones is demonstrated by numerical examples. The simulation performed in the Matlab environment confirmed the correctness of the obtained results.

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