FUZZY CONTROLLER FOR THE CONTROL OF THE MOBILE PLATFORM OF THE CORBYS ROBOTIC GAIT REHABILITATION SYSTEM

In this paper, an inverse kinematics based control algorithm for the joystick control of the mobile platform of the novel mobile robot-assisted gait rehabilitation system CORBYS is presented. The mobile platform has four independently steered and driven wheels. Given the linear and angular velocities of the mobile platform, the inverse kinematics algorithm gives as its output the steering angle and the driving angular velocity of each of the four wheels. The paper is focused on the steering control of the platform for which a fuzzy logic controller is developed and implemented. The experimental results of the real-world steering of the platform are presented in the paper

Dynamics of liquid and solids flow in oscillatory flow reactors and application to biochemical reaction with immobilized enzymes

Disertacija obuhvata eksperimentalno i teorijsko istraţivanje osnovnih fluido – dinamiĉkih karakteristika kontinualnih jednofaznih i višefaznih reaktora sa oscilatornim tokom fluida (ROT). Pored ispitivanja dinamike strujanja teĉnosti i ĉestica, u okviru ove teze ispitivana je i mogućnost primene ROT na reakciju sinteze galaktooligosaharida (GOS) pomoću slobodnih i imobilisanih enzima. U prvom poglavlju dat je detaljan pregled dosadašnjih istraţivanja koja se odnose na reaktore sa oscilatornim tokom fluida. Prikazane su karakteristike, prednosti i nedostaci ROT predstavljeni u literaturi. Posebno su prikazani i rezultati istraţivanja potencijalne industrijske primene ovog tipa ureĊaja. U drugom poglavlju „Dinamika strujanja teĉnosti u ROT“ prikazani su rezultati eksperimentalnog ispitivanja strujanja, tj. raspodele starosti teĉnosti na izlazu, u dva geometrijski sliĉna reaktora sa oscilatornim tokom fluida duţine 2 m i unutrašnjeg preĉnika 44 i 26 mm. Primenjena je metoda praćenja odziva sistema na impulsnu promenu obeleţene supstance ĉija koncentracija je merena u vremenu pomoću spektrofotometra. Na osnovu eksperimentalnih rezultata utvrĊen je uticaj operativnih parametara (frekvencija, amplituda i protok peristaltiĉke pumpe) na raspodelu starosti teĉnosti na izlazu iz ispitivanih reaktora sa oscilatornim tokom fluida. Primenom modela klipnog strujanja sa aksijalnom disperzijom, a na osnovu eksperimentalnih rezultata razvijena je matematiĉka korelacija koja povezuje bezdimenzioni Pekleov broj sa bezdimenzionim brojevima koji opisuju oscilatorni tok teĉnosti u reaktorima: oscilatorni Rejnoldsov broj, Strauhalov broj i odnos oscilatornog i Rejnoldsovog broja neto protoka. Razvijena korelacija je pored eksperimentalnih vrednosti ove disertacije verifikovana i uz pomoć eksperimentalnih rezultata dostupnih u literaturi. U trećem poglavlju „Dinamika strujanja ĉestica“ prikazani su rezultati eksperimentalnog i teorijskog istraţivanja naĉina proticanja ĉestica u kontinualnom reaktoru sa oscilatornim tokom fluida (unutrašnjeg preĉnika 26 mm) u koji se ĉestice uvode kontinualno. Primenom metode praćenja odziva sistema na stepenastu promenu obeleţenih ĉestica utvrĊen je uticaj operativnih parametara – frekvencije, amplitude ikoncentracije ĉestica na ulazu u reaktor, na kumulativnu krivu vremena zadrţavanja ĉestica u reaktoru. Kako bi se odredila koncentracija obeleţenih (obojenih) ĉestica, fotografije uzoraka su analizirane u programskom paketu ImageJ. Pored toga, ispitan je i kvantifikovan uticaj operativnih parametara na naĉin proticanja ĉestica i stešnjeno taloţenje, srednje vreme zadrţavanja kao i na udeo (zadrţanih) ĉestica u reaktoru. Teorijski i eksperimentalno su utvrĊeni kriterijumi za odreĊivanje 4 reţima proticanja ĉestica: puzajući reţim strujanja ĉestica, zgušnjeno strujanje ĉestica, razblaţeni tok ĉestica i odnošenje ĉestica...The dissertation presents experimental and theoretical investigation of the main fluid dynamic characteristics of continuous single – phase and multiphase fluid flow in continuous oscillatory flow reactors (COFR). In addition, the possibility of COFR application to reaction of galactooligosaccharides (GOS) synthesis with free – flow and immobilized enzymes was studied within this thesis. The first chapter provides a detailed overview of the research related to oscillatory flow reactors (OFR). Further, the characteristics, advantages and disadvantages of OFR presented in the literature are discussed. In addition, the possibilities of industrial application for this type of device are presented. In the second chapter "Dynamics of fluid flow in the OFR", the results of experimental investigation of the liquid residence time distribution (RTD) in two geometrically similar reactors with oscillatory flow of liquid are presented.. Reactors were 2 m in length and with internal diameter of 44 and 26 mm. The impulse response method with a tracer was applied. The concentration of the tracer in the samples was determined by measuring the absorbance using a spectrophotometer. The influence of operating parameters (frequency, amplitude and flow rate of the peristaltic pump) on the RTD in the reactors was determined. Using a plug flow with axial dispersion model and experimental results, an empirical correlation was derived. Developed correlation relates the dimensionless Peclet number to dimensionless numbers describing the oscillatory fluid flow in the reactors: oscillatory Reynolds number, Strauhal number and ratio of oscillatory and net Reynolds number. In addition to the experimental results of this dissertation, the correlation was verified using experimental results from the literature. The third chapter "Dynamics of solids flow in the OFR" presents the results of experimental and theoretical investigation of the liquid – solids flow in continuous oscillatory flow reactor (internal diameter of 26 mm) into which the solids are introduced continuously. The influence of operating parameters – frequency, amplitude and concentration of solids at the inlet of the reactor, on solids cumulative residencetime curve (F) in the reactor was determined using the step response method with a tracer (solids of a different color). In order to determine concentration of tracer, the photos of samples were analysed using the ImageJ software. In addition, the influence of operating parameters on the solids flow regime, hindered particle settling, mean residence time as well as solids holdup in the reactor was examined and quantified. Four solids flow regimes were identified theoretically and experimentally: creeping solids flow, dense solids flow, dilute solids flow and solids washout..

Hemijski reaktori sa oscilirajućim tokom fluida

Global market competition, increase in energy and other production costs, demands for high quality products and reduction of waste are forcing pharmaceutical, fine chemicals and biochemical industries, to search for radical solutions. One of the most effective ways to improve the overall production (cost reduction and better control of reactions) is a transition from batch to continuous processes. However, the reactions of interests for the mentioned industry sectors are often slow, thus continuous tubular reactors would be impractically long for flow regimes which provide sufficient heat and mass transfer and narrow residence time distribution. The oscillatory flow reactors (OFR) are newer type of tube reactors which can offer solution by providing continuous operation with approximately plug flow pattern, low shear stress rates and enhanced mass and heat transfer. These benefits are the result of very good mixing in OFR achieved by vortex generation. OFR consists of cylindrical tube containing equally spaced orifice baffles. Fluid oscillations are superimposed on a net (laminar) flow. Eddies are generated when oscillating fluid collides with baffles and passes through orifices. Generation and propagation of vortices create uniform mixing in each reactor cavity (between baffles), providing an overall flow pattern which is close to plug flow. Oscillations can be created by direct action of a piston or a diaphragm on fluid (or alternatively on baffles). This article provides an overview of oscillatory flow reactor technology, its operating principles and basic design and scale-up characteristics. Further, the article reviews the key research findings in heat and mass transfer, shear stress, residence time distribution in OFR, presenting their advantages over the conventional reactors. Finally, relevant process intensification examples from pharmaceutical, polymer and biofuels industries are presented.Ekonomski i ekološki pritisci, kao što su globalna konkurencija, povećanje energetskih i drugih troškova proizvodnje, zahtevi za visokim kvalitetom proizvoda i smanjenje otpada, primoravaju farmaceutsku, finu hemijsku i biohemijsku industriju na radikalne promene u proizvodnji. Jedan od efikasnih načina za sveobuhvatno poboljšanje proizvodnje (smanjenje troškova i bolju kontrolu reakcije) je prelazak sa tradicionalno šaržnih procesa na kontinualne. Međutim, reakcije od interesa za pomenute industrijske sektore su često spore, pa bi kontinualni cevni reaktori trebalo da budu nepraktično velikih dužina za režime strujanja koji obezbeđuju zadovoljavajuće prenose toplote i mase i uske raspodele vremena zadržavanja. Reaktori sa oscilirajućim tokom fluida (ROT) nude rešenje jer obezbeđuju kontinualni rad, strujanje blisko klipnom, visoke prenose mase i toplote, a pri tom se mogu koristiti male brzine strujanja, te su reaktori prihvatljivih dužina za spore reakcije. Ove pozitivne karakteristike se ostvaruju zbog jako dobrog mešanja u reaktoru, usled stvaranja vrtloga pri sudaru generisanog talasa fluida sa internim pregradama. Osim navedenih prednosti u ROT se obezbeđuju i niži smicajni naponi (za isti unos energije) u odnosu na reaktore sa mehaničkim mešalicama, što je značajno za aplikacije u biohemijskom i biomedicinskom inženjerstvu. U ovom preglednom radu je predstavljen princip rada ovih reaktora, različite konstrukcije i osnovni kriterijumi za projektovanje. Prikazani su reprezentativni rezultati istraživanja, koji jasno potvrđuju prednosti ovih uređaja u odnosu na konvencionalne i navedeni su primeri intenzifikacije procesa primenom ROT u različitim industrijskim sektorima, kao što su farmaceutski, polimerni, biogoriva, prerada otpadnih voda i dr

Solids flow pattern in continuous oscillatory baffled reactor

Transition from batch to continuous processing is an attractive alternative for the production of pharmaceutical, fine and bio chemicals. In a number of such industrial reactions or separations, a solid phase is present either as a reactant, product or catalyst. Instead of conventional continuous reactors, the utilization of oscillatory flow reactors could be advantageous. The flow pattern of solids in a continuous oscillatory baffled reactor (COBR), into which solids are introduced continuously, was investigated experimentally and theoretically. The effects of operating conditions on a solids flow regime, solids mean residence time and dispersion and solids holdup were analyzed and quantified. Four solids flow regimes named as: Creeping solids flow, Dense solids flow, Dilute solids flow and Solids washout, were identified based on the ratio of the maximum oscillatory axial velocity to hindered settling velocity of particles, input power per volume for oscillatory flow and the concentration ratio between adjacent cells. The results demonstrate that increasing frequency and/or amplitude decreases the axial dispersion of solids, the ratio of solids to fluid mean residence time and the solids holdup. Inlet solids concentration has no significant influence on the axial dispersion but considerably affects the solids mean residence time and the solids holdup

Recent development of bioaugmentation methods for tobacco wastewater treatment

In production of cigarettes a lot of tobacco waste, with nicotine, goes into the environment. Hence, there is a need for an economic and efficient method to diminish the discharge of hazardous materials from tobacco wastewaters. Bioaugmentation using specialized bacteria strains could improve the efficiency of tobacco wastewater treatment. In this review paper we present bioaugmentation methods for tobacco wastewater treatment that were published in last few years. Bioaugmentation systems have proven to be very effective in removal of nicotine and TOC; it was shown that Pseudomonas sp. HF-1 and TW bacteria strains can be successfully used in reactors. Recent studies showed that controlling pH in the reactors can improve reactor performance in removing nicotine and TOC from tobacco wastewater

Gait Trajectory Prediction using Gaussian Process Ensembles

The development of robotic devices for the rehabilitation of gait is a growing area of interest in the engineering rehabilitation community. The problem with modelling gait dynamics is that everybody walks differently. The approach advocated in this paper addresses this issue by modelling the gait dynamics of individual patients. Specifically, we present a model learner which performs automated system identification of patient gait. The model learner consists of an ensemble of multiple-input-single-output Gaussian Processes which feature automatic relevance determination kernels for automated tuning of parameters. First, the paper presents results for the application of the Gaussian Process ensemble to the learning of a particular patient's gait using a typical prediction configuration. Generalisation of gait prediction is tested with multiple patients and cross-validation. Finally, initial results are presented in which the Gaussian Process ensemble is shown to be capable of learning the mapping between the patient's gait and the therapist-assisted gai