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Title:POLOŽAJNO VODENJE ROBOTSKEGA MEHANIZMA S PIEZOELEKTRIČNIMI AKTUATORJI
Authors:ID Čas, Jure (Author)
ID Šafarič, Riko (Mentor) More about this mentor... New window
ID Gotlih, Karl (Comentor)
Files:.pdf DR_Cas_Jure_2011.pdf (4,90 MB)
MD5: F6E8FD79E4EAB7A99A2C02055C4998AB
PID: 20.500.12556/dkum/3369dee6-0452-4d8a-abf5-12ebad9b4c51
 
Language:Slovenian
Work type:Dissertation
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:V disertaciji je predstavljeno modeliranje, izdelava in položajno vodenje ravninskega robotskega mehanizma s piezoelektričnimi aktuatorji. Robotski mehanizem je sestavljen iz steklenega ogrodja in dveh piezoelektričnih aktuatorjev. Sprememba dolžine piezoelektričnih aktuatorjev se preko steklenega ogrodja z vgrajenim prestavnim razmerjem prenaša na vrh robotskega mehanizma, kjer predstavlja njegov delovni pomik. Velikost robotskega mehanizma je približno 40x40 milimetrov, velikost delovne ravnine pa je približno 25x25 mikrometrov. Z uporabo piezoelektričnih aktuatorjev je vrh robotskega mehanizma mogoče pozicionirati s pod-mikrometrsko natančnostjo. Kakorkoli, zaradi nelinearnega histereznega pojava v piezoelektričnih aktuatorjih je takšno natančnost brez ustreznih metod za položajno vodenje nemogoče zagotoviti. Zaradi tega je bil zasnovan in implementiran sistem za položajno vodenje robotskega mehanizma, ki vključuje napetostne ojačevalnike za napajanje piezoelektričnih aktuatorjev, merilno opremo za meritev dejanskega položaja vrha robotskega mehanizma in kontrolno-procesno enoto s programsko opremo na kateri se izvajajo algoritmi oziroma metode za položajno vodenje. Uporaba tradicionalnih metod vodenja, kot je PI regulator, pri položajnem vodenju vrha robotskega mehanizma zaradi nelinearnosti proge ne daje povsem zadovoljivih rezultatov. Zaradi tega smo za ocenitev in kompenzacijo nelinearnosti na progi (predvsem histereze v piezoelektričnih aktuatorjih) uporabili usmerjene nevronske mreže, ki so znane kot univerzalno orodje za ocenitev in kompenzacijo nelinearnih pojavov. Eksperimentalni rezultati, ki so bili pridobljeni na realnem robotskem mehanizmu, potrjujejo, da je z uporabo nevronskih mrež mogoče izboljšati rezultate tradicionalnih metod vodenja tako pri položajnem vodenju vrha robotskega mehanizma v odprti zanki kot tudi v zaprti zanki.
Keywords:piezoelektrični mehanizem, položajno vodenje, nelinearni sistem, histereze, usmerjene nevronske mreže, vzvratno razširjanje
Place of publishing:Maribor
Publisher:[J. Čas]
Year of publishing:2011
PID:20.500.12556/DKUM-18165 New window
UDC:004.032.26:681.5(043.3)
COBISS.SI-ID:14930710 New window
NUK URN:URN:SI:UM:DK:QAUK07CC
Publication date in DKUM:04.05.2011
Views:2770
Downloads:201
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FERI
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Secondary language

Language:English
Title:POSITION CONTROL OF ROBOTIC MECHANISM WITH PIEZOELECTRIC ACTUATORS
Abstract:This thesis presents modelling, design and position control of a planar robot mechanism with piezoelectric actuators. Robot mechanism consists of a glass frame and two piezoelectric actuators. The length displacement of piezoelectric actuators is transmitted through a glass frame with built-in transfer ratio at the tip of the robotic mechanism, where it is represented as his working shift. The size of the robot mechanism is approximately 40x40 millimetres and the size of the working plane is approximately 25 by 25 micrometres. By employing piezoelectric actuators the tip of robotic mechanism can be positioned with sub-micrometre accuracy. However, due to the nonlinear hysteresis effect of piezoelectric actuators, this functionality is not guaranteed without the appropriate position control. Concerning these observations, a system for position control of robot mechanism has been designed and implemented. The implemented system includes voltage power amplifiers for piezoelectric actuators, the metering equipment for measuring the actual position of the robot mechanism's tip and control-processing unit with software equipment and algorithms for position control. Due to the nonlinearity of controlled plant, the use of traditional control methods, such as PI controller, does not give very satisfactory results. Therefore, for evaluation and compensation of plant nonlinearities (hysteresis in piezoelectric actuators), we use feedforward neural networks, which are known as a universal tool for evaluation and compensation of nonlinear phenomena. Experimental results obtained on real robot mechanism confirm, that the use of neural networks can improve the performance of traditional open-loop and also close-loop control methods for position control of robot mechanism.
Keywords:piezoelectric mechanism, position control, nonlinear system, hysteresis, feedforward neural networks, backpropagation


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