Естимација крутости и адаптивно управљање код попустљивих робота

Although there has been an astonishing increase in the development of nature- inspired robots equipped with compliant features,i.e.soft robots, their full potential has not been exploited yet. One aspect is that the soft robotics research has mainly focused on their position control only, whilest iffness is managed in open loop. Moreover, due to the difficulties of achieving consistent production of the actuation systems for soft articulated robots and the time-varyingnatureoftheirinternalflexibleelements,whicharesubjecttoplasticdeformation overtime,itiscurrentlyachallengetopreciselydeterminethejointstiffness. . In this regard, the thesis puts an emphasis on stiffness estimation and adaptive control for soft articulated robots driven by antagonistic Variable Stiffness Actuators (VSAs) with the aim to impose the desired dynamics of both position and stiffness, which would finally contribute to the overall safety and improved performance of a soft robot. By building upon Unknown Input Observer (UIO) theory, invasive and non-invasive solutions for estimation of stiffness in pneumatic and electro-mechanical actuators are proposed and in the latter case also experimentally validated. Beyond the linearity and scalability advantage, the approaches have an appealing feature that torque and velocity sensors are not needed. Once the stiffness is determined, innovative control approaches are introduced for soft articulated robots comprising an adaptive compensator and a dynamic decoupler. The solutions are able to cope with uncertainties of the robot dynamic model and, when the desired stiffness is constant or slowly-varying, also of the pneumatic actuator. Their verification is performed via simulations and then the pneumatic one is successfully tested on an experimental setup. Finally, the thesis shows via extensive simulations the effectiveness of adaptive technique ap- plied to soft-bodied robots, previously deriving the sufficient and necessary conditions for the controller convergence.Iako se danas izuzetno intenzivno radi na razvoju robota inspirisanih prirodom koje odlikuje elastična struktura, njihov puni potencijal jox uvek nije iskorišćen. Sa jedne strane, istraživanja u oblasti popustljivih robota su uglavnom fokusirana samo na upravljanje njihovom pozicijom, dok se krutost reguliše u otvorenoj sprezi. Pored toga, zbog poteškoća u postiznju konzistentne proizvodnje aktuatora i promenljive prirode njihovih elastičnih elemenata, koji su vremenom podlo_ni plastičnoj deformaciji, trenutno je izazov precizno odrediti krutost zglobova robota. U cilju doprinosa poboljšanja_u performansi i bezbednosti rada popustivih robota, teza prikazuje doprinos proceni krutosti i adaptivnog simultanog upravljanja pozicijom i krutosti antagonističkih aktuatora promenljive krutosti (VSA). Oslanjajući se na teoriju opservera nepoznatih ulaza (UIO), predložena su invazivna i neinvazivna rešenja za procenu krutosti u pneumatskim i elektromehaničkim aktuatorima i eksperimentalno verifikovana u slučaju druge grupe aktuatora. Pored linearnosti i skalabilnosti, ovi pristupi imaju privlaqnu osobinu da senzori momenta i brzine nisu potrebni. Teza predla_e inovativne sisteme upravljanja koji poseduju adaptivni kompenzator i dinamički dekupler. Predložene metode upravljanja demonstriraju mogućnost da kompenzuju nesigurnosti dinamičkog modela robota bez obzira da li je on pogođen električnim ili pneumatskim aktuatorima. Nakon simulacija, razvijeno upravljanje je verifikovano i na pneumatskom robotu. Na kraju teze, obimne simulacije pokazuju efikasnost adaptivne tehnike kada se primeni na robote sa fleksibilnim linkovima, prethodno izvodeći dovoljne i potrebne uslove za konvergenciju kontrolera

Kinetic model of toner separation from fiber suspension

Izdvajanje čestica tonera iz vodene suspenzije papira ispitivano je na sintetičkim uzorcima celuloznih vlakana i čestica tonera da bi se eliminisao uticaj sraslaca vlakno - čestica kao i uticaj krupnoće čestica tonera na efikasnost procesa flotiranja tonera uz konstantan maseni odnos vlakana celuloze i čestica tonera. Takođe da bi se obezbedile iste fizičko hemijske karakteristike tonera kao nakon dezintegracije štampanog papira, sintetički uzorak je pripremljen postupkom topljenja u cilju simuliranja procesa oksidopolimerizacije do koje dolazi prilikom štampanja na laserskom štampaču, usitnjavanjem i prosejavanjem na seriji sita radi dobijanja srednjeg prečnika čestica tonera približnom prečniku pri dezintegraciji štampanog papira. Rezultati analiza SEM i DSC pokazale su da je moguće pripremiti sintetički uzorak koji ima skoro identične fizičko hemijske karakteristike kao i realni uzorak štampanog tonera nakon procesa dezintegracije. Nakon obrade literature usvojili su se konstantni optimalni parametri u procesu flotacije, temperatura tečne faze, sadržaj čvrste faze, brzina agitacije, protok vazduha, vreme kondicioniranja, dok su promenljivi parametri u procesu flotacije bili vrsta i koncentracija surfakanata (oleinska kiselina koncentracije od 3,38 10-6 M/dm3 do 2,03 10-4M/dm3 sa ili bez dodatka kalcijum hlorida 3 10-3M/dm3, MIBC koncentracije 1,40 10-5 M/dm3 do 5,60 10-5M/dm3), kao i pH vrednost sredine (od pH 3 do 12). Radi upoređivanja ostvarenih rezultata sa rezultatima iz literature, testiranja i analiziranja kinetičkih modela izdvajanja čestica tonera iz suspenzije papira, definisani su optimalni uslovi pri kojima se ostvaruje dobra selektivnost u procesu flotacije (oleinska kiselina 3,38 10-6 M/dm3 pri pH 9; oleinska kiselina 2,37 10-5 M/dm3 u prisustvu kalcijum hlorida 3 10-3 M/dm3 pri pH 3; MIBC 1,40 10-5 M/dm3 pri pH 7 i 9; MIBC 2,40 10-5 M/dm3 pri pH 9 i 12). Rezultati eksperimentalnih istraživanja izdvajanja čestica tonera iz vodene suspenzije papira pri definisanim optimalnim uslovima, ukazuju na mogućnost primene postupka flotacije radi dobijanja dobre selektivnosti izdvojenog tonera u proizvodu pene (I) i prečišćenih vlakana celuloze u proizvodu otoka (Y) preko 90 %, tako da su kinetički modeli (klasičan model prvog...The flotation of toner has been tested on the synthetic samples of the cellulose fibers and toner particles in order to eliminate the influence of middlings: fiber-particle as well as the influence of toner particle sizes on flotation process efficiency of toner accompanied by the constant mass relation between the cellulose fibers and toner particles. In order to provide the same toner physical-chemical features, the same way as after the printed paper disintegration, the synthetic sample has been prepared by the melting procedure in order to achieve the simulation of the process of oxidopolymerization, which occurs during the process of printing on the laser printer, by comminuting and screening on the screen series for the sake of obtaining the middle diameter of the toner particles which would be close to that diameter while the printing paper is being disintegrated. The results of SEM and DSC analyses have shown that it is possible to prepare the synthetic sample which has got almost the same identical physical and chemical features as the real sample of the printed toner after the process of disintegration. After dealing with literature, there were adopted the constant optimal parameters in the flotation process, the temperature of the liquid state, the content of the solid, the agitation speed, the air flow, the conditioning time, while the variable parameters in the flotation process were a type and a concentration of a surfactant (oleic acid concentration from 3,38 10-6 M/dm3 up to 2,03 10-4 M/dm3 with or without any addition of the calcium chloride 3 10-3 M/dm3, MIBC concentration from 1,40 10-5 M/dm3 to 5,6 10-5 M/dm3), as well as the pH value of the medium (from pH 3 to 12). For the sake of comparing the achieved results to the ones from the Literature, the testing and analyzing of kinetic models of the toner flotation, there were defined the optimal conditions under which it is possible to achieve a good selectivity in the process of flotation (oleic acid 3,38 10-6 M/dm3 with pH 9; oleic acid 2,37 10-5 M/dm3 with pH 7 and 9; MIBC 2,4 10-5 M/dm3 with pH 9 and 12). The results of the experimental researches relating to the flotation of toner with the defined optimal conditions, point to the possibility of applying the flotation process for the sake of obtaining a good..

Естимација крутости и адаптивно управљање код попустљивих робота

Although there has been an astonishing increase in the development of nature- inspired robots equipped with compliant features,i.e.soft robots, their full potential has not been exploited yet. One aspect is that the soft robotics research has mainly focused on their position control only, whilest iffness is managed in open loop. Moreover, due to the difficulties of achieving consistent production of the actuation systems for soft articulated robots and the time-varyingnatureoftheirinternalflexibleelements,whicharesubjecttoplasticdeformation overtime,itiscurrentlyachallengetopreciselydeterminethejointstiffness. . In this regard, the thesis puts an emphasis on stiffness estimation and adaptive control for soft articulated robots driven by antagonistic Variable Stiffness Actuators (VSAs) with the aim to impose the desired dynamics of both position and stiffness, which would finally contribute to the overall safety and improved performance of a soft robot. By building upon Unknown Input Observer (UIO) theory, invasive and non-invasive solutions for estimation of stiffness in pneumatic and electro-mechanical actuators are proposed and in the latter case also experimentally validated. Beyond the linearity and scalability advantage, the approaches have an appealing feature that torque and velocity sensors are not needed. Once the stiffness is determined, innovative control approaches are introduced for soft articulated robots comprising an adaptive compensator and a dynamic decoupler. The solutions are able to cope with uncertainties of the robot dynamic model and, when the desired stiffness is constant or slowly-varying, also of the pneumatic actuator. Their verification is performed via simulations and then the pneumatic one is successfully tested on an experimental setup. Finally, the thesis shows via extensive simulations the effectiveness of adaptive technique ap- plied to soft-bodied robots, previously deriving the sufficient and necessary conditions for the controller convergence.Iako se danas izuzetno intenzivno radi na razvoju robota inspirisanih prirodom koje odlikuje elastična struktura, njihov puni potencijal jox uvek nije iskorišćen. Sa jedne strane, istraživanja u oblasti popustljivih robota su uglavnom fokusirana samo na upravljanje njihovom pozicijom, dok se krutost reguliše u otvorenoj sprezi. Pored toga, zbog poteškoća u postiznju konzistentne proizvodnje aktuatora i promenljive prirode njihovih elastičnih elemenata, koji su vremenom podlo_ni plastičnoj deformaciji, trenutno je izazov precizno odrediti krutost zglobova robota. U cilju doprinosa poboljšanja_u performansi i bezbednosti rada popustivih robota, teza prikazuje doprinos proceni krutosti i adaptivnog simultanog upravljanja pozicijom i krutosti antagonističkih aktuatora promenljive krutosti (VSA). Oslanjajući se na teoriju opservera nepoznatih ulaza (UIO), predložena su invazivna i neinvazivna rešenja za procenu krutosti u pneumatskim i elektromehaničkim aktuatorima i eksperimentalno verifikovana u slučaju druge grupe aktuatora. Pored linearnosti i skalabilnosti, ovi pristupi imaju privlaqnu osobinu da senzori momenta i brzine nisu potrebni. Teza predla_e inovativne sisteme upravljanja koji poseduju adaptivni kompenzator i dinamički dekupler. Predložene metode upravljanja demonstriraju mogućnost da kompenzuju nesigurnosti dinamičkog modela robota bez obzira da li je on pogođen električnim ili pneumatskim aktuatorima. Nakon simulacija, razvijeno upravljanje je verifikovano i na pneumatskom robotu. Na kraju teze, obimne simulacije pokazuju efikasnost adaptivne tehnike kada se primeni na robote sa fleksibilnim linkovima, prethodno izvodeći dovoljne i potrebne uslove za konvergenciju kontrolera

Modeling and prediction of flotation performance using support vector regression

Continuous efforts have been made in recent year to improve the process of paper recycling, as it is of critical importance for saving the wood, water and energy resources. Flotation deinking is considered to be one of the key methods for separation of ink particles from the cellulose fibres. Attempts to model the flotation deinking process have often resulted in complex models that are difficult to implement and use. In this paper a model for prediction of flotation performance based on Support Vector Regression (SVR), is presented. Representative data samples were created in laboratory, under a variety of practical control variables for the flotation deinking process, including different reagents, pH values and flotation residence time. Predictive model was created that was trained on these data samples, and the flotation performance was assessed showing that Support Vector Regression is a promising method even when dataset used for training the model is limited

Analysis of Surface Water Quality and Sediments Content on Danube Basin in Djerdap-Iron Gate Protected Areas

As water is essential to life and is an indispensable resource for ecosystems and their services and for nearly all human activities, the goal of this research was to evaluate the surface water quality of the Danube as it passes through the Romania–Serbia border in the nature reservations Djerdap and Iron Gate. The study aimed to assess the oxygen regime, nutrients and heavy metals contamination of the surface waters of the Danube on a length of about 240 km, between Bazias and Iron Gate II. Reference sampling and analytical methods (UV-VIS and AAS) were deployed to reach this goal. In addition, sediments were analyzed through back scattered SEM-EDAX for the elemental analysis of the sediment surface. Results obtained show a low environmental impact of heavy metals, while the Danube’s oxygen regime is under stress due to nutrients’ (nitrites and orthophosphates) significant concentration in the Danube surface water in the analyzed sector. Our approach can be applied to other water bodies in the area, to increase available scientific data together with societal awareness of the Danube’s environmental risks

Elbow Joint Stiffness Functional Scales Based on Hill’s Muscle Model and Genetic Optimization

The ultimate goal of rehabilitation engineering is to provide objective assessment tools for the level of injury and/or the degree of neurorehabilitation recovery based on a combination of different sensing technologies that enable the monitoring of relevant measurable variables, as well as the assessment of non-measurable variables (such as muscle effort/force and joint mechanical stiffness). This paper aims to present a feasibility study for a general assessment methodology for subject-specific non-measurable elbow model parameter prediction and elbow joint stiffness estimation. Ten participants without sensorimotor disorders performed a modified “Reach and retrieve” task of the Wolf Motor Function Test while electromyography (EMG) data of an antagonistic muscle pair (the triceps brachii long head and biceps brachii long head muscle) and elbow angle were simultaneously acquired. A complete list of the Hill’s muscle model and passive joint structure model parameters was generated using a genetic algorithm (GA) on the acquired training dataset with a maximum deviation of 6.1% of the full elbow angle range values during the modified task 8 of the Wolf Motor Function Test, and it was also verified using two experimental test scenarios (a task tempo variation scenario and a load variation scenario with a maximum deviation of 8.1%). The recursive least square (RLS) algorithm was used to estimate elbow joint stiffness (Stiffness) based on the estimated joint torque and the estimated elbow angle. Finally, novel Stiffness scales (general patterns) for upper limb functional assessment in the two performed test scenarios were proposed. The stiffness scales showed an exponentially increasing trend with increasing movement tempo, as well as with increasing weights. The obtained general Stiffness patterns from the group of participants without sensorimotor disorders could significantly contribute to the further monitoring of motor recovery in patients with sensorimotor disorders