Solid State Phenomena Vols. 147-149

Abstract: In this paper the identification method of the parameter representing the inertia of masses flowing water throw the pipes in water power plants has been presented. The value of this parameter is used in adaptable method of synchronizing power generators. The identification based on the simplified mathematical model of the hydro-turbine and initial phase of the response to synchronizing power object. Application mathematical model compose synchronous generator during idle work, hydro-turbine with long pipes and large head and controller of governor. Identification Tw parameter process consists of two steps. The first step is connected with analyzing initial phase of transient characteristic. And the next point is connected with determinate coefficients of linear flattening and characteristic point. This point is realized by sending control signals of angular velocity from automatic synchronizer to controller. This cause changing frequency of voltage which is the next (point by point) registered in selected moments in matrix. A shown synchronization method is

Abstract: Piezoelectric friction actuating mechanism is chosen to construct long traveling range sub-micro X-Y positioning table. LuGre friction model is employed to simulate the friction dynamics of this positioning mechanism. The optimization scheme of Matlab toolbox is adopted to search the optimal friction model parameters. However, this piezoelectric actuating system has obvious nonlinear and time-varying dead-zone offset control voltage due to the static friction and preload. The estimated LuGre dynamic model is still not accurate enough for model-based precision control design. Hence, the adaptive sliding mode control (SMC) with robust behavior is employed to design the nonlinear controller for this piezoelectric friction actuating mechanism. The Laypunov-like design strategy is adopted to achieve the system stability criterion. The dynamic experimental results of the proposed nonlinear controllers are compared with that of a model-based PID controller, too.

Abstract: In this paper we study the stabilization problem of double inverted pendulum via wlywheel actuator. The main issue of the paper is whether such system can be stabilized in real conditions or not. It is shown that the answer strongly depends on the structural (geometric and physical) parameters of the system. The paper gives the procedure for optimizing these parameters under specified conditions to obtain the most robust closed loop system.

Abstract: This paper describes the development of a neural network control for shape memory alloy (SMA) actuators as well as the control tests. Precise control of SMA actuators that are integrated in the composite structure is difficult because of the hysteretic behaviour of SMA and time delays in the control system. The weakness of the static model of SMA is that it does not take into account the actuator dynamics. The NARMA-L2 neural network model enables us to solve the inverse dynamic model of the nonlinear discrete-time dynamical system. In this study the NARMA-L2 model of the airfoil (a cross section of wind turbine blade) was created using Matlab Simulink software and neural networks. Data for network training was measured from the specimen. The performance of the constituted NARMA-L2 controller was tested in control tests. According to the control tests the NARMA-L2 controller is well suited for controlling embedded SMA actuators. The constituted controller enabled fast and stable actuation in step responses and it was also able to compensate for changes in cooling conditions.

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Abstract: The paper deals with semi-active chatter absorber based on an electrodynamic transducer built around high-energy permanent magnets. Also, a fuzzy logic control system for the absorber control system has been designed. The principal advantage of fuzzy control is the possibility to implement practical experience gained by machine operators in the control algorithm. Hence, the possibility of factoring such quantities, as vibrations experienced by selected points of the machine-tool, and sound emitted by working machine into the analyzed chatter absorber fuzzy control system has been studied in the paper. The control system has been tested by way of simulation with the use of the process and cutting force models.

Abstract: The 3D vehicle with the hydraulic braking system and disc brake with the wheel has been investigated. The dynamic models of the disk brake assembly and the wheel have been constructed. The automobile hydraulic braking system consisting of two contours is considered. . The mathematical model of the hydraulic braking system is presented, where the flow of liquid and the interaction of liquid with the rigid bodies are taken into account. The flow of fluid in a hydraulic system is described by a system of equations of a hyperbolic type, which is solved by a characteristics method. During the mathematical simulations and natural experimentations the following results were achieved. The systems of equations of dynamic models’ motions are solved by numerical methods. The dynamic characteristics of the braking system of the automobile are obtained. The results of extreme braking tests and calculations are presented.

Abstract: An optimal robust vibration control of a rotor supported magnetically over a wide angular speed range is presented in the paper. The laboratory stand with the high speed rotor (max. 24000 rpm) was designed. The wide bandwidth controller with required gain, which is necessary to stabilize the structurally unstable and active magnetic bearing system was computed. For controller design, the weighting functions putted on the input and output signals were chosen. For control design, the dynamics of the rotor and uncertain parameters were considered. The optimized control system by minimization of the H norm putted on transient process of the system was presented. The robust controller was designed with considered asymmetrically magnetic bearings, signal limits and power amplifiers dynamic. The success of the robust control is demonstrated through computer simulations and experimental results. Matlab-Simulink was used for the numerical simulation. The experimental results show the effectiveness of the control system as good vibrations reducing and robustness of the designed controller in all dynamic states.

Abstract: This paper deals with condition monitoring and vibration diagnostics of vertical sulphuric acid pumps running in continuous long term operation mode. The task of experimental testing and theoretical modeling – to increase reliability and efficiency of vertical pumps through elimination of rotor lateral vibration. On the basis of experimental testing results analysis the dynamic model was designed and simulated. The reason of high vibration of the pump rotor is the rotor technological bow and cavitation phenomenon that take place in the pump.

Abstract: This paper presents results of numerical analysis of dynamics of a microstructure under the influence of air damping, which is modeled by linearized compressible Reynolds equation. Developed finite element model accounts for air rarefaction and is valid in a wide pressure range. Simulation results indicate that the influence of air damping may result not only in a pronounced dissipative effect but also in natural frequency shift due to system stiffening caused by air compression. This phenomenon is observed under combination of particular values of system and excitation parameters