Ramutis Bansevicius

Piezomechanics as a subsystem of mechatronics: present state of the art, problems, future developments

The concept of piezomechanics (piezoelectricity+mechanics+a control system) describing a complex interaction of dynamic effects and precision engineered devices is discussed. Piezomechanics is considered as part of the more broad philosophy of mechatronic devices. The object and structure of piezomechanics are presented as well as the primary linear and nonlinear effects, on which energy, motion and signal transformation processes are based. Novel applications are proposed to illustrate the potential benefits, including adaptive mechanical systems in addition to multifunctional and intelligent devices.

Investigation of tribological properties in piezoelectric contact

The aim of the paper is to describe the ways to increase the reliability of the piezoelectric motors, related to tribological processes of the contact zones piezoelectric transducer—rotor or slider, in which both static forces and ultrasonic two dimensional vibrations are taking place. The problems of frictional wear are dealt with introducing and realizing the concept of adaptive tribological pair with optimal rheological parameters of components, enabling to effect self-diagnostics of the pair by exploiting direct piezoelectric effect of already existing piezoelectric transducers. This will allow for the forecast of durability and its significant increase when using new advanced materials (including nano-particles). Some results of experiments are given, including correlation of diagnostic signals with the parameters of wear.

Mechatronic means for machine accuracy improvement

The paper deals with the mechatronic means for the accuracy improvement of metal cutting machines, co-ordinate measuring machines, robots, etc. The mechatronic correction means of raster scales, encoders errors and final 3-D position correction of a cutting instrument or touch probe are presented. The technical solutions are given with the application of active materials for smart probes and piezoactuators. A case of calculations for piezoactive raster plates is described together with volumetric control diagrams and the examples of practical implementation.

Optimal Electrodes Configuration of Piezodrives

This paper presents a study of optimisation of the electrodes dislocation of piezodrives. The following conditions of optimisation problem are considered: to unify excitation voltage forms, to achieve reverse motion and maximum coefficient of efficiency. Realisation of this requirement means that current source has to generate voltage of constant frequency, amplitude and phase, reverse motion must be achieved only through changing the polarity of the current source and that the surface of the piezodrive is fully covered with electrodes. FEM modelling is performed in calculating process. The results of calculations for the piezoelectric drive are shown for two options of fixing conditions.

The effect of fluorine oligomer coatings on the tribocontacts of a piezoelectric actuator

The tribological study of the parameters of piezoactuator when switching over contacts a trib- ocouple deals with of rotation of piezoactuator steady during 500 m when the rotor from polished steel C45 (HRC 50, Ra = 2 μm) is used. Often the rotation speed leaps up to 16-18 min-1. The coating with fluoroli- gomeric material stabilizes the rotation and continuous operation of piezoactuator. The steady rotation speed starts from a 50-m run (350 rotor revolutions, i.e., cycles of repeating impacts on the surface). The lower dam- age of the friction surface takes place after a 500-m run when the rotor is coated with fluoroligomeric mate- rial. Scratch tests show that steel surface with the fluoroligomeric layer has a lower hardness and 20% higher elasticity compared to a noncoated surface.

Analysis dynamics of piezoelectric optical scanner with periodical microstructure

Piezoelectric optical scanner is developed for multi-coordinate control of optical laser beam by excitation of microstructures. The manufactured microstructure is the grating which implemented in piezoelectric optical scanner. Such type of opto-micro-mechanical systems can be used for accurate angular or linear deflection of optical elements in various optomechanical and optoelectronic systems. The operating principle of these devices is based on piezoelectric effect and on conversion of high-frequency multi-dimensional mechanical oscillations of piezoelectric vibration transducers into directional multi-coordinate motion of the optical elements in the measurement chain. The main distinctive feature of such optical piezoelectric scanners is the combination of high micrometer range resolution with a wide range of angular deflections of the scanning elements. The manufacturing process and visualization of the microstructure were presented. The device consists of piezoelectric cylinder and a scanning element with three degrees of freedom. The control model of this device was derived using simulation of the working regimes of optical scanner by COMSOL Multiphysics software. Optical holography system was used to validate the result of simulation of piezoelectric optical scanner and to test the functionality of piezoelectric optical scanner with implemented microstructures.

Development of Laser Rifle Trainer with Full Shot Imitation

Laser trainers are effective tools for shot and sportsmen training. However, the majority of trainers have neither realistic recoil nor sound imitation systems. The objective of the development of laser rifle trainer with full shot imitation was to investigate and simulate the recoil of combat weapons under single and serial shooting regimes so that the training weapons could simulate complete recoil and sound imitation. Theoretical and experimental investigations lead to the development of shot training systems which were successfully implemented in Lithuanian Army combat training facilities. The laser trainers are also equipped with interactive software interface which does not only control and register the process of shooting but also can reproduce the whole set of statistical data, including psychological impact on the rifleman and detection of his training problems. The incorporation of multimedia advances the system up to interactive laser shot trainer in virtual combat reality.

Development of Traveling Wave Actuators Using Waveguides of Different Geometrical Forms

The paper covers the research and development of piezoelectric traveling wave actuators using different types of the waveguides. The introduced piezoelectric actuators can be characterized by specific areas of application, different resolution, and torque. All presented actuators are ultrasonic resonant devices and they were developed to increase amplitudes of the traveling wave oscillations of the contact surface. Three different waveguides are introduced, that is, symmetrical, asymmetrical, and cone type waveguide. A piezoelectric ring with the sectioned electrodes is used to excite traveling wave oscillations for all actuators. Operating principle, electrode pattern, and excitation regimes of piezoelectric actuators are described. A numerical modelling of the actuators was performed to validate the operating principle and to calculate trajectories of the contact points motion. Prototype actuators were made and experimental study was performed. The results of numerical and experimental analysis are discussed.

Development of a Novel Device for Attitude Control over Small Satellites

Recent years have faced a very modern trend for space exploration activities – constructing, launching and operating nanosatellites have become very popular. One of the major problems of implementing and taking control over the nanosatellite is ensuring accurate but simple and small dimension equipment for attitude control. Most of the equipment implemented for the introduced task was large and bulky in the past and could be hardly used on extremely small satellites. The paper describes equipment under development for attitude control over satellites. Equipment relies on the implementation of piezoelectric transducers for the rotation of a spherical body, i.e. reaction sphere, thus ensuring precise three-axis attitude control over the satellite by means of a single device. Further, the article focuses on the device under development with some calculations and examples of implementing such instruments.

Attitude Control of Micro- and Nanosatellites Using Multi-degree-of-Freedom Piezoelectric Actuators

The paper deals with new approach to control attitude of small satellites by using high resolution multi-degree-of-freedom piezoelectric motors and piezoelectric transducers, generating travelling wave oscillations in the plane, perpendicular to satellite’s rotation axis. It leads to the increase of the resolution of system to enable orienting the payload in a precise direction, extends the range of temperatures to the direction of both positive and negative values and significantly reduces the cost and simplifies the design. Theoretical analysis of described attitude control mechanisms is presented.