Comparison of hysteresis of high accuracy positioning system with piezoelectric actuators

In the paper, high accuracy positioning systems with flexible elements are investigated. In the analyzed systems, piezoelectric actuators are used for the transmission of motion and the hystereric phenomenon in them is investigated. Effect of the hysteretic phenomena to the precision of the high accuracy positioning systems is of special importance. For the investigations, a special experimental setup was designed and produced as well as the method of the experimental procedure was proposed. The experimental setup includes a computer, a piezocontroller, an inductive displacement sensor and a dynamic data collector. The dynamic data collector is used for the collection of data and for the transfer of data to the software for further processing. Numerical modelling of the hysteretic was performed by using the Matlab/Simulink software. In the process of investigations, it was determined that the maximum dispersion error of the hysteretic model is less than 5 % when compared with the experimental results. Thus, it is concluded that the proposed method of hysteretic phenomenon modelling is suitable for modelling of high accuracy positioning systems with flexible elements, which are controlled by piezoelectric actuators

Investigation of effect of acoustic field to coagulation of particles in air flow

In the paper theoretical and experimental investigations of the effect of acoustic field to coagulation of particles in air flow are presented. For the conduction of experimental investigations, a special experimental setup with measurement devices was designed and used. Principle of operation of the proposed experimental setup is presented and the method of conduction of experimental investigations is described. Investigations of effectiveness of coagulation of rigid particles of very small diameter have been performed and dependencies from the sound pressure of the acoustic field and its frequency were investigated. For excitation of the acoustic field two sound generators were used: piezoelectric and aeroacoustic. As a result of the performed investigations it was determined that with the increase of the frequency of acoustic excitation velocity of coagulation of particles increases when the diameter of the particles does not exceed 1 μm. For the most effective coagulation of the particles having the diameter up to 1 μm ultrasonic frequency is required. For the particles with the diameter larger than 1 μm frequency lower than ultrasonic is required. Dependencies of velocity of coagulation of particles from the frequency of acoustic signal and from its amplitude were determined. Initial granulometric constituent parts were compared with the constituent parts obtained after the experimental investigations