Electrical characteristics of eddy current position sensor

In the thesis the principle of work of eddy current position sensors and the main cautions that must be taken into account while sensor design process are explained. A way of automated eddy current position sensor electrical characteristics measurement is suggested. A prototype of the eddy current position sensor and its electrical characteristics are investigated. The results obtained by means of the automated measuring system are explained.

Energy harvesting methods for wireless sensor nodes in heavy-duty vehicles

The number of autonomous wireless sensor and control nodes has been increasing rapidly during the last decade. Until recently, these wireless nodes have been powered with batteries, which have lead to a short life cycle and high maintenance need. Due to these battery-related problems, new energy sources have been studied to power wireless nodes. One solution is energy harvesting, i.e. extracting energy from the ambient environment. Energy harvesting can provide a long-lasting power source for sensor nodes, with no need for maintenance. In this thesis, various energy harvesting technologies are studied whilst focusing on the theory of each technology and the state-of-the-art solutions of published studies and commercial solutions. In addition to energy harvesting, energy storage and energy management solutions are also studied as a subsystem of a whole energy source solution. Wireless nodes are also used in heavy-duty vehicles. Therefore a reliable, long-lasting and maintenance-free power source is also needed in this kind of environment. A forestry harvester has been used as a case study to study the feasibility of energy harvesting in a forestry harvester’s sliding boom. The energy harvester should be able to produce few milliwatts to power the target system, an independent limit switch.

Methods and Models for Accelerating Dynamic Simulation of Fluid Power Circuits

The objective of this dissertation is to improve the dynamic simulation of fluid power circuits. A fluid power circuit is a typical way to implement power transmission in mobile working machines, e.g. cranes, excavators etc. Dynamic simulation is an essential tool in developing controllability and energy-efficient solutions for mobile machines. Efficient dynamic simulation is the basic requirement for the real-time simulation. In the real-time simulation of fluid power circuits there exist numerical problems due to the software and methods used for modelling and integration. A simulation model of a fluid power circuit is typically created using differential and algebraic equations. Efficient numerical methods are required since differential equations must be solved in real time. Unfortunately, simulation software packages offer only a limited selection of numerical solvers. Numerical problems cause noise to the results, which in many cases leads the simulation run to fail. Mathematically the fluid power circuit models are stiff systems of ordinary differential equations. Numerical solution of the stiff systems can be improved by two alternative approaches. The first is to develop numerical solvers suitable for solving stiff systems. The second is to decrease the model stiffness itself by introducing models and algorithms that either decrease the highest eigenvalues or neglect them by introducing steady-state solutions of the stiff parts of the models. The thesis proposes novel methods using the latter approach. The study aims to develop practical methods usable in dynamic simulation of fluid power circuits using explicit fixed-step integration algorithms. In this thesis, twomechanisms whichmake the systemstiff are studied. These are the pressure drop approaching zero in the turbulent orifice model and the volume approaching zero in the equation of pressure build-up. These are the critical areas to which alternative methods for modelling and numerical simulation are proposed. Generally, in hydraulic power transmission systems the orifice flow is clearly in the turbulent area. The flow becomes laminar as the pressure drop over the orifice approaches zero only in rare situations. These are e.g. when a valve is closed, or an actuator is driven against an end stopper, or external force makes actuator to switch its direction during operation. This means that in terms of accuracy, the description of laminar flow is not necessary. But, unfortunately, when a purely turbulent description of the orifice is used, numerical problems occur when the pressure drop comes close to zero since the first derivative of flow with respect to the pressure drop approaches infinity when the pressure drop approaches zero. Furthermore, the second derivative becomes discontinuous, which causes numerical noise and an infinitely small integration step when a variable step integrator is used. A numerically efficient model for the orifice flow is proposed using a cubic spline function to describe the flow in the laminar and transition areas. Parameters for the cubic spline function are selected such that its first derivative is equal to the first derivative of the pure turbulent orifice flow model in the boundary condition. In the dynamic simulation of fluid power circuits, a tradeoff exists between accuracy and calculation speed. This investigation is made for the two-regime flow orifice model. Especially inside of many types of valves, as well as between them, there exist very small volumes. The integration of pressures in small fluid volumes causes numerical problems in fluid power circuit simulation. Particularly in realtime simulation, these numerical problems are a great weakness. The system stiffness approaches infinity as the fluid volume approaches zero. If fixed step explicit algorithms for solving ordinary differential equations (ODE) are used, the system stability would easily be lost when integrating pressures in small volumes. To solve the problem caused by small fluid volumes, a pseudo-dynamic solver is proposed. Instead of integration of the pressure in a small volume, the pressure is solved as a steady-state pressure created in a separate cascade loop by numerical integration. The hydraulic capacitance V/Be of the parts of the circuit whose pressures are solved by the pseudo-dynamic method should be orders of magnitude smaller than that of those partswhose pressures are integrated. The key advantage of this novel method is that the numerical problems caused by the small volumes are completely avoided. Also, the method is freely applicable regardless of the integration routine applied. The superiority of both above-mentioned methods is that they are suited for use together with the semi-empirical modelling method which necessarily does not require any geometrical data of the valves and actuators to be modelled. In this modelling method, most of the needed component information can be taken from the manufacturer’s nominal graphs. This thesis introduces the methods and shows several numerical examples to demonstrate how the proposed methods improve the dynamic simulation of various hydraulic circuits.

Heat flux measurement inside internal combustion engine with gradient heat flux sensor.

This master’s thesis is devoted to study different heat flux measurement techniques such as differential temperature sensors, semi-infinite surface temperature methods, calorimetric sensors and gradient heat flux sensors. The possibility to use Gradient Heat Flux Sensors (GHFS) to measure heat flux in the combustion chamber of compression ignited reciprocating internal combustion engines was considered in more detail. A. Mityakov conducted an experiment, where Gradient Heat Flux Sensor was placed in four stroke diesel engine Indenor XL4D to measure heat flux in the combustion chamber. The results which were obtained from the experiment were compared with model’s numerical output. This model (a one – dimensional single zone model) was implemented with help of MathCAD and the result of this implementation is graph of heat flux in combustion chamber in relation to the crank angle. The values of heat flux throughout the cycle obtained with aid of heat flux sensor and theoretically were sufficiently similar, but not identical. Such deviation is rather common for this type of experiment.

Controlling full penetration in MAG welding by the application of infrared thermography and neural network

In this study, an infrared thermography based sensor was studied with regard to usability and the accuracy of sensor data as a weld penetration signal in gas metal arc welding. The object of the study was to evaluate a specific sensor type which measures thermography from solidified weld surface. The purpose of the study was to provide expert data for developing a sensor system in adaptive metal active gas (MAG) welding. Welding experiments with considered process variables and recorded thermal profiles were saved to a database for further analysis. To perform the analysis within a reasonable amount of experiments, the process parameter variables were gradually altered by at least 10 %. Later, the effects of process variables on weld penetration and thermography itself were considered. SFS-EN ISO 5817 standard (2014) was applied for classifying the quality of the experiments. As a final step, a neural network was taught based on the experiments. The experiments show that the studied thermography sensor and the neural network can be used for controlling full penetration though they have minor limitations, which are presented in results and discussion. The results are consistent with previous studies and experiments found in the literature.

Venttiili- ja toimilaitetehtaan tuotannon suunnittelu

Venttiili- ja toimilaitetehtaassa kokoonpannaan erilaisia venttiilityyppejä sekä toimi- laitteita. Koko Metso Automationin Helsingin tehtaiden tuotantotilanteen muuttuessa käynnistettiin kehitysprojekti, jonka tarkoituksena oli uudenaikaistaa venttiilien ja toimilaitteiden valmistus vastaamaan nykypäivän vaatimuksia. Laajamittaisen osa- valmistuksen ulkoistuksen ja tuotteiston muutoksen vuoksi tuotannon uudelleen- järjestäminen oli välttämätöntä. Diplomityön tarkoituksena oli suunnitella venttiili- ja toimilaitetehtaan layout sekä uutta tuotantotilannetta vastaavat toimintatavat. Haasteena oli kolmen hyvin erilailla toimivan tuotetehtaan yhdistäminen yhdeksi kokonaisuudeksi, jossa kunkin tehtaan parhaat toimintatavat yhdistyvät. Nykyinen tuotanto ja valmistusmäärät kartoitettiin ja analysoitiin, minkä jälkeen tuotannon suunnittelu uusiin tiloihin käynnistettiin. Työ jaettiin järjestelmällisesti osiin teorian ja käytännön osuuksien kesken siten, että teoria tukee työn käytännön- osuutta. Apuna käytettiin useita erilaisia materiaalivirtojen kartoitusmenetelmiä, lukuisia mittareita, selvityksiä, ennusteita ja erilaisia malleja tulevasta tuotannosta. Layout suunniteltiin käytössäolevaan tehdashalliin, mikä aiheutti runsaasti haasteita ja rajoitteita. Aikataulu tehtiin tarkasti siten, että muuttojärjestys lyötiin lukkoon, mutta kuormitustilanne ja koneiden siirrot aiheuttivat muutoksia aikataulussa. Tavoite tuotannon häiriöttömyydestä toteutui hyvin aikataulun kustannuksella. Käytännönosuudessa tarkasteltiin erityisesti kapasiteetin joustavuutta kuormituksen vaihdellessa sekä kehitettiin toimintatavat, joilla se hallitaan. Lisäksi tutkimuksen aikana käynnistettiin useita kehitysprojekteja työn tulosten pohjalta. Näitä olivat erilaiset varaston hallintaan sekä solujen itseohjautuvuuteen liittyvät asiat. Diplomityön tuloksena saatiin uusi layout sekä sitä tukeva uusi toimintatapa, solujen itseohjautuvuuden kehittäminen käynnistettiin, varastojen hallinnan osittainen ulkoistaminen aloitettiin. Lisäksi tuotannolle kehitettiin lukuisia seurantamittareita. Layoutprojekti toteutettiin loppuun diplomityön aikana

Kokeellisen moodianalyysin hyödyntäminen sääriluun lujuuden määrittämisessä

Diplomityö tehtiin Lappeenrannan teknillisen yliopiston konetekniikan laitokselle. Diplomityö on osa teknillisen yliopiston biomekaanista tutkimusta, jonka tarkoituksena on mallintaa ihmisen tuki- ja liikuntaelimistön toimintaa. Työssä pyrittiin selvittämään, voitaisiinko sääriluuhun kohdistetun mekaanisen herätteen aiheuttamaa värähtelyvastetta analysoimalla saada tietoa luun ominaistaajuuksista ja lujuudesta. Tietoa voitaisiin käyttää esimerkiksi ostoporoosiriskin arvioinnissa sekä ihmiskehon osien toimintaa kuvaavien simulointimallien verifioinnissa. Mittauslaitteistona käytettiin Brüel & Kjær-moodianalyysilaitteistoa. Laitteistokokonaisuuteen kuuluivat herätevasara, elektromagneettinen täristin, voima-anturi, kaksi kiihtyvyysmitta-anturia sekä PulseLab 2.0 –ohjelmistolla varustettu PC-laitteisto. Tulosten jatkoanalyysi suoritettiin MathWorks yhtiön MatLab v 4.0 -ohjelmistolla. Työssä esitellyn mittaustavan ja -laitteiston todettiin soveltuvan sääriluun värähtelyvasteen mittaamiseen. Mittaustulokset eri mittauskertojen välillä samalla henkilöllä ovat yhtenevät. Tutkimuksen tulosten perusteella ei voida osoittaa luun värähtelyvasteen ja lujuuden välistä suoraa korrelaatiota.

AMB system for high-speed motors using automatic commissioning

The general trend towards increasing e ciency and energy density drives the industry to high-speed technologies. Active Magnetic Bearings (AMBs) are one of the technologies that allow contactless support of a rotating body. Theoretically, there are no limitations on the rotational speed. The absence of friction, low maintenance cost, micrometer precision, and programmable sti ness have made AMBs a viable choice for highdemanding applications. Along with the advances in power electronics, such as signi cantly improved reliability and cost, AMB systems have gained a wide adoption in the industry. The AMB system is a complex, open-loop unstable system with multiple inputs and outputs. For normal operation, such a system requires a feedback control. To meet the high demands for performance and robustness, model-based control techniques should be applied. These techniques require an accurate plant model description and uncertainty estimations. The advanced control methods require more e ort at the commissioning stage. In this work, a methodology is developed for an automatic commissioning of a subcritical, rigid gas blower machine. The commissioning process includes open-loop tuning of separate parts such as sensors and actuators. The next step is to apply a system identi cation procedure to obtain a model for the controller synthesis. Finally, a robust model-based controller is synthesized and experimentally evaluated in the full operating range of the system. The commissioning procedure is developed by applying only the system components available and a priori knowledge without any additional hardware. Thus, the work provides an intelligent system with a self-diagnostics feature and an automatic commissioning.

Lämpövuoanturin mittauselektroniikan suunnittelu ja toteutus

Energian kulutuksen vähentäminen ja sen tutkiminen on kasvavan kiinnostuksen kohteena. Syntyneen lämmön mittaaminen on yksi tapa mitata energian siirtymistä. Lämpötilan mittaaminen on yleistä, vaikka usein on merkittävämpää selvittää missä ja miten lämpöenergia on siirtynyt. Tästä syystä tarvitaan lämpövuoantureita, jotka reagoivat suoraan lämpövuohon eli lämpöenergian siirtymiseen. Tässä tutkimuksessa suunnitellaan ja toteutetaan lämpövuoanturin mittauselektroniikka vaativaan käyttöympäristöön. Työssä käytettävän gradienttilämpövuoanturin tuottama jännitesignaali on mikrovolttiluokkaa ja ympäristön aiheuttama kohina voi olla huomattavasti suurempi. Tämän takia anturin tuottamaa signaalia on vahvistettava, jotta sitä voidaan mitata luotettavasti. Tutkimuksessa keskitytään vahvistimen suunnitteluun, mutta suunnittelussa on otettava huomioon koko järjestelmä. Anturin sähköiset ominaisuudet ja ympäristö asettavat rajoitteita vahvistimelle. Tavoitteena on selvittää miten voidaan mitata mikrovolttien jännitesignaalia mahdollisimman suurella taajuuskaistalla vaativassa käyttöympäristössä. Työn tuloksena syntyi mittalaite, jota voidaan käyttää vaativassa ympäristössä lämpövuon mittaamiseen. Suunnitteluparametrien mukainen vahvistus ja päästökaista sekä offset-jännitteen ryömintä saavutettiin suunnitellulla mittalaitteella, mutta offsetjännite ja kohina olivat hieman suunniteltua suuremmat. Mittalaitteella ja lämpövuoanturilla havaittiin selvästi lämpövuon muutoksia keinotekoisilla herätteillä.

Development of a Control System for a Tele Operated Mobile Robot

Mobile robots are capable of performing spatial displacement motions in different environments. This motions can be calculated based on sensorial data (autonomous robot) or given by an operator (tele operated robot). This thesis is focused on the latter providing the control architecture which bridges the tele operator and the robot’s locomotion system and end effectors. Such a task might prove overwhelming in cases where the robot comprises a wide variety of sensors and actuators hence a relatively new option was selected: Robot Operating System (ROS). The control system of a new robot will be sketched and tested in a simulation model using ROS together with Gazebo in order to determine the viability of such a system. The simulated model will be based on the projected shape and main features of the real machine. A stability analysis will be performed first theoretically and afterwards using the developed model. This thesis concluded that both the physical properties and the control architecture are feasible and stable settling up the ground for further work with the same robot.

Panossyöttökasvatusprosessin automatisointi

Tutkimuskäyttöön tarkoitettujen rekombinanttiproteiinien tuottaminen fermentoimalla on yleinen menetelmä bioteollisuudessa. Mikrobit kasvatetaan fermentorissa, joka tarjoaa kontrolloidun kasvuympäristön ja sopivat tuotto-olosuhteet halutulle tuotteelle. Eräs fermentointimuodoista on korkeatuottoinen ja pitkäkestoinen panossyöttökasvatus, jossa saavutetaan panoskavatusta merkittävästi korkeampi solutiheys jatkamalla panosvaiheen jälkeen kasvua rajoittavan substraatin syöttöä. Laboratoriomittakaavassa fermentorikasvatusten tilavuudet vaihtelevat litrasta kymmeniin ja niissä kasvatusta seurataan sekä ohjataan joko fermentorista tai tietokoneesta. Tyypillisessä fermentointiprosessissa operaattori tarkkailee muun muassa vaahdonkorkeutta sekä käynnistää pumppuja olosuhteiden muuttuessa. Tällaiset tehtävät ovat teollisen mittakaavan laitteistoissa usein automatisoituja. Diplomityön tarkoituksena oli päivittää kahden Turun yliopiston biotekniikan laboratoriossa sijaitsevan BioFlo® -sarjan pöytäfermentorin MS-DOS -pohjainen tietokoneohjausohjelma nykyaikaiseksi ja lisätä siihen etäseuranta ja -ohjaus. Ohjelmaan oli tarkoitus liittää erillinen optinen solutiheysanturi, jonka lukemien häiriötä haluttiin myös vähentää signaalinkäsittelyllä. Lisäksi vaahdonestoaineen ja indusorin lisäykset haluttiin automatisoida panossyöttökasvatuksessa. Vaahdonkorkeuden havaitsemisen mahdollisuutta konenäön menetelmin haluttiin selvittää, jotta vaahdonestoaineen automaattiset lisäykset voitaisiin toteuttaa nettikameran syötteen perusteella. Koekasvatuksilla osoitettiin päivitetyn ohjausohjelman toimivan panos- ja panossyöttömuodoilla. Uuden käyttöliittymän avulla pystyttiin automatisoimaan panoskasvatuksen lisäykset ja syöttönopeuden muutokset sekä tunnistamaan kasvatusliuosten vaahdonkorkeutta vaahdonestoaineen lisäykseen riittävällä kahden senttimetrin tarkkuudella. Lisäksi käyttöliittymä mahdollisti kasvatuksen ohjauksen ja seurauksen myös etänä. Työssä kehitetty ohjausohjelma julkaistiin avoimena ohjelmana ilman etä- ja nettikameratoimintoja. Ohjelma toimii hyvin BioFlo® -sarjan fermentorien käyttöliittymänä, mutta avoimen lähdekoodin ansiosta kuka tahansa voi hyödyntää ohjelmaa pohjana myös uusissa projekteissa tai muissa fermentorimalleissa.

Multi-sensor Simultaneous Localization and Mapping

Simultaneous localization and mapping(SLAM) is a very important problem in mobile robotics. Many solutions have been proposed by different scientists during the last two decades, nevertheless few studies have considered the use of multiple sensors simultane¬ously. The solution is on combining several data sources with the aid of an Extended Kalman Filter (EKF). Two approaches are proposed. The first one is to use the ordinary EKF SLAM algorithm for each data source separately in parallel and then at the end of each step, fuse the results into one solution. Another proposed approach is the use of multiple data sources simultaneously in a single filter. The comparison of the computational com¬plexity of the two methods is also presented. The first method is almost four times faster than the second one.

Sensor Fusion of Proprioception, Force and Vision in Estimation and Robot

Sensor-based robot control allows manipulation in dynamic environments with uncertainties. Vision is a versatile low-cost sensory modality, but low sample rate, high sensor delay and uncertain measurements limit its usability, especially in strongly dynamic environments. Force is a complementary sensory modality allowing accurate measurements of local object shape when a tooltip is in contact with the object. In multimodal sensor fusion, several sensors measuring different modalities are combined to give a more accurate estimate of the environment. As force and vision are fundamentally different sensory modalities not sharing a common representation, combining the information from these sensors is not straightforward. In this thesis, methods for fusing proprioception, force and vision together are proposed. Making assumptions of object shape and modeling the uncertainties of the sensors, the measurements can be fused together in an extended Kalman filter. The fusion of force and visual measurements makes it possible to estimate the pose of a moving target with an end-effector mounted moving camera at high rate and accuracy. The proposed approach takes the latency of the vision system into account explicitly, to provide high sample rate estimates. The estimates also allow a smooth transition from vision-based motion control to force control. The velocity of the end-effector can be controlled by estimating the distance to the target by vision and determining the velocity profile giving rapid approach and minimal force overshoot. Experiments with a 5-degree-of-freedom parallel hydraulic manipulator and a 6-degree-of-freedom serial manipulator show that integration of several sensor modalities can increase the accuracy of the measurements significantly.

Synthesis, characterization and chemical sensor application of conducting polymers

Polymeric materials that conduct electricity are highly interesting for fundamental studies and beneficial for modern applications in e.g. solar cells, organic field effect transistors (OFETs) as well as in chemical and bio‐sensing. Therefore, it is important to characterize this class of materials with a wide variety of methods. This work summarizes the use of electrochemistry also in combination with spectroscopic methods in synthesis and characterization of electrically conducting polymers and other π‐conjugated systems. The materials studied in this work are intended for organic electronic devices and chemical sensors. Additionally, an important part of the presented work, concerns rational approaches to the development of water‐based inks containing conducting particles. Electrochemical synthesis and electroactivity of conducting polymers can be greatly enhanced in room temperature ionic liquids (RTILs) in comparison to conventional electrolytes. Therefore, poly(para‐phyenylene) (PPP) was electrochemically synthesized in the two representative RTILs: bmimPF6 and bmiTf2N (imidazolium and pyrrolidinium‐based salts, respectively). It was found that the electrochemical synthesis of PPP was significantly enhanced in bmimPF6. Additionally, the results from doping studies of PPP films indicate improved electroactivity in bmimPF6 during oxidation (p‐doping) and in bmiTf2N in the case of reduction (n‐doping). These findings were supported by in situ infrared spectroscopy studies. Conducting poly(benzimidazobenzophenanthroline) (BBL) is a material which can provide relatively high field‐effect mobility of charge carriers in OFET devices. The main disadvantage of this n‐type semiconductor is its limited processability. Therefore in this work BBL was functionalized with poly(ethylene oxide) PEO, varying the length of side chains enabling water dispersions of the studied polymer. It was found that functionalization did not distract the electrochemical activity of the BBL backbone while the processability was improved significantly in comparison to conventional BBL. Another objective was to study highly processable poly(3,4‐ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) water‐based inks for controlled patterning scaled‐down to nearly a nanodomain with the intention to fabricate various chemical sensors. Developed PEDOT:PSS inks greatly improved printing of nanoarrays and with further modification with quaternary ammonium cations enabled fabrication of PEDOT:PSS‐based chemical sensors for lead (II) ions with enhanced adhesion and stability in aqueous environments. This opens new possibilities for development of PEDOT:PSS films that can be used in bio‐related applications. Polycyclic aromatic hydrocarbons (PAHs) are a broad group of π‐conjugated materials consisting of aromatic rings in the range from naphthalene to even hundred rings in one molecule. The research on this type of materials is intriguing, due to their interesting optical properties and resemblance of graphene. The objective was to use electrochemical synthesis to yield relatively large PAHs and fabricate electroactive films that could be used as template material in chemical sensors. Spectroscopic, electrochemical and electrical investigations evidence formation of highly stable films with fast redox response, consisting of molecules with 40 to 60 carbon atoms. Additionally, this approach in synthesis, starting from relatively small PAH molecules was successfully used in chemical sensor for lead (II).