Papers by Keyword: Actuator

Abstract: Piezoelectric materials such as lead-zirconate-titanate (PZT), lead-metaniobate, and piezo-composites are the materials of choice for acoustic imaging in medical diagnosis as well as underwater ultrasonic microphones and underwater sonar. PZT materials have the advantage of having high electro-mechanical coupling, low internal losses and excellent environmental durability. Nonetheless, in order to improve energy transmission the high acoustic impedance of piezoelectric ceramics needs to be matched to the lower acoustic impedance of biological tissues and water. For actuators resonated in their thickness mode, energy transmission can be improved by means of intermediate layers of material of carefully selected thicknesses and acoustic properties. Sometimes a backing layer is also added to the back of the actuator to damp the acoustic back-wave. The process of making these types of transducers is generally costly due to the nature of the manufacturing process and the required level of accuracy. This paper describes an inexpensive method of manufacture low-cost, low-impedance, piezoelectric transducers. The fundamental physical principles behind this new type of sensor-actuator, as well as various examples of imaging low-impedance targets using a prototype of this newly developed sensor-actuator system will be presented.

Abstract: A Planar square stack coupled inductor coils on silicon substrate has been fabricated using MEMS technology. The fabrication process utilized a simple, cost effective process technique as well as CMOS compatible resulting to a reproducible and good controlled process. The basic characteristics of the coupled inductors were discussed in wide range of operating frequency. The analysis results showed that the geometry of the inductor coil strongly affects the basic characteristics of the coils. The results of the study have promised a good prospect for the development of fully integrated planar magnetic field generator for sensing and actuating purposes.

Abstract: In this paper, tests on Shape Memory Alloy (SMA) wires for use in controlled actuators have been discussed. Selected static and dynamic characteristic curves being the result of experiments were presented in the article. Experiments were conducted at the Dynamics and Control of Structures Laboratory of the AGH University of Science and Technology. Laboratory tests of SMA wires used as actuators have been presented in the paper. Actuators made from the wires contract by about 4-5% of their length when heated, like small muscles, and loosen when cooled. SMA wires used as drives are significantly smaller than traditional solutions using motors or electromagnet to execute work. However, these actuators have flaws, such as strongly non-linear hysteresis. These are main problems in designing actuators, which is why SMA wires are often used in the construction of two-state actuators working as on-off actuators. The problems with SMA wires in their applications as drives are their static and dynamic properties, sensitivity to the environment, poor repeatability of production, non-linearity and hysteresis loop. The tested wires were made from a nickel and titanium alloy; this is an alloy which is often used in drive systems.

Abstract: Work presents a proposal of an analysis method of the piezoelectric transducer. The considered system is a longitudinally vibrating single PZT plate. The main aim of this work is to designate characteristics of the considered PZT plate. Using constitutive equations of piezoelectric materials and an equation of the plates motion a matrix of characteristics of the system was obtained. Relations between mechanical and electrical parameters (forces, displacements, electric current and voltage) that describe behaviour of the system are included in the matrix of characteristics. A dynamic flexibility relation between the plates deformation and a force applied to the system is considered. A structural damping of the plates material was being taken into consideration and its influence on the plates dynamic flexibility is analysed. This work is an introduction to a task of analysis of complex systems. In future work the developed model and proposed mathematical algorithm will be used to analyse piezoelectric stacks. Non-classical methods will be used. It is a part of research works of Gliwice research centre related with an analysis and synthesis of mechanical and mechatronic systems [4-7,9,10,16-18]. Passive and active mechanical and mechatronic systems with piezoelectric transducers were analysed [1-3]. Works were also supported by computer-aided methods [8]. Both classical and non-classical methods were being considered. The discussed subject is important due to increasing number of applications of both simple and reverse piezoelectric phenomena in various modern technical devices.

Abstract: This paper analyses the area in which synchronic operation of several pneumatic actuators connected by a rigid link exists. The minimum values of the supplied compressed air have been determined under which self-exciting vibrations appear in the system of several actuators. The influence of the transducers geometrical parameters on the variation law of motion of the system working organ has been investigated. It has determined that character of dependencies of peak-to-peak and frequency upon pressure of system is similar to character of dependencies separate transducer and that having picked up geometrical and dynamic parameters actuators it is possible to receive difficult (biharmonic) movement of system. This property can be applied in vibrostands meant for material or equipment trials and their vibrational processing.

Abstract: Magnetic Shape Memory Alloys (MSMA) constitute one of the newest groups of intelligent materials [. Although these materials have yet to find commercial applications, literature with information on the first pre-prototype actuators can already be found. The mechanism of operation of these actuators is based on the magnetic shape memory effect. During tests, the shifting of piston and current in the coil of the electromagnet were measured. Measurements were synchronized with set courses of this current coil of the actuator. The obtained results made it possible to make static characteristics for constant levels of current, and dynamic curves for constant values of frequency as well as to construct a mathematical model. In this work, the authors have described laboratory tests of an experimental actuator of this type.

Abstract: This paper presents the development of an innovative control, regulation and command system for hydronic radiant floors, more flexible and efficient that guarantees a better thermal comfort to the user and simultaneously improves the energy efficiency of this type of heating system. The majority of the actual control of hydronic radiant floors is done by thermostats that measure the air temperature and control the actuators (pumps and valves) in order to maintain the room at the specified temperature. These systems requires the frequent adjustment of thermostats set-point in order to obtain thermal comfort as it depends on other factors than just the air temperature, such as, the air humidity, external environmental conditions, radiant temperature, among others. This paper presents a control, regulation and command solution that requires minimum user intervention, as the user only has to choose the desirable thermal comfort level. The control algorithm is based on the calculation of PMV (Predicted Mean Vote) index as defined on Thermal Comfort Standard ISO 7730. Another advantage of the proposed system is related to the wireless and energy harvesting sensors and actuators that provide much more flexibility to the system.

Abstract: The article contains information about the function and basic properties of the actuator based on pneumatic artificial muscles. It describes the design method of control structure of such actuator and shows the configuration of the non-linear actuator together with non-linear (compensation) control unit. The second upgrading method is based on the other mechanical configuration of the actuator. The artificial muscle force is transmitted by free pulley and has the practically linear static characteristic. The resulting position servosystem with linearized overall static characteristics has favorable results and better operation abilities. They are presented by experimentally measured step responses.

Abstract: In this work, a PPy actuator was fabricated by galvanostatic electropolymerization. The electrochemical deformation behaviors of the PPy actuator were investigated in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), containing different concentrations of methanol. Marked improvement of the actuating strain of approximately 9% was achieved when the actuator was driven by a potential between –1 and 1 V in the LiTFSI electrolyte containing 40 to 50% of methanol under a load stress of 0. 3 MPa. On the other hand, the actuator functioned in the electrolyte solutions containing more than 60% of methanol showed rapid decrease of the actuating strain and the electrochemical creep after repeated actuations. Possible mechanisms for these behaviors were discussed.

Abstract: In this contribution is presented design of camera system location at the station for loading and orientation at the intelligent assembly cell. This intelligent cell is situated at the Institute of Production System and Applied Mechanics. The complex design of camera system is going out the intelligent manufacturing systems knowledge. The cell is used for assembly pneumatic actuators. These actuators are consisting of four parts. These parts - semi products of pneumatic actuators are transported from station for loading and orientation, shelf storage system to the workplace of intelligent assembly cell. At the station for loading and orientation is designed camera system for identification assembly parts (rollers and pistons).