Design of adjustable packaging line

Diplomityön tavoite oli tutkia, mitä toimintoja ja tekniikoita uusi, joustava kartonkipakkauslinja sisältää ja mitkä suuntaukset pakkausteollisuudessa tulevat olemaan tärkeitä tulevaisuudessa. Pakkauslinjan päätoimintoja tarkasteltiin nykyisten jatulevaisuuden tekniikoiden pohjalta. Erityisesti tarkasteltiin laser-sovellusten käytön mahdollisuutta pakkauslinjan eri osatoiminnoissa. Katsaus pakkausteollisuuden tulevaisuuden näkymiin luotiin kirjallisuuden ja aikaisempien tutkimusten pohjalta, minkä perusteella työssä oletetaan, että yksilölliset ja monitoimipakkaukset tulevat lisääntymään tulevaisuudessa. Eri tuotantoerien välillä olevat asetusajat tulee saada minimoitua, mutta millä keinoin joustavuus on saavutettavissa? Yksi ratkaisu pakkausten valmistamisessa on käyttää robottisolua, mikä on mahdollista luultavasti ainakin kuppimuotoisten pakkausten kohdalla. Muutenkin robotiikka on lisääntymässä pakkausteollisuudessa. Digitaalisten painotekniikoiden kehitys on mahdollistanut yksilölliset painatukset. Tulevaisuudessa painatus on mahdollista tehdä pakkauslinjan loppupäässä, jopa vasta täytön ja suljennan jälkeen. Laserleikkaus on jo nyt käytössä, mutta tulevaisuudessa myös saumaus ja perinteinen nuuttaus on mahdollista tehdä lasersovelluksia käyttäen. Kehittynyt, väyläpohjainen ohjausjärjestelmä on tulevaisuudessa välttämätön joustavassa pakkauslinjassa. Internetin välityksellä toimiva etäohjattu virheenkorjausdiagnostiikka tulee myös olemaan itsestäänselvyys tulevaisuudessa. Kustannussäästöjä voidaan saavuttaa käyttämälläpakkauslinjassa modulaarista rakennetta. Standardiosien ja standardiosajärjestelmien käyttäminen pienentää myös käyttö- ja huoltokustannuksia. Tärkeää on kuitenkin muistaa, ettei joustavuutta voida saavuttaa pelkästään yhtä ominaisuutta tai tekniikkaa hyödyntäen vaan monia menetelmiä yhdistäen. Suunniteltavan pakkauslinjan toiminta on myös hyvä varmistaa käyttäen apuna mallinnusta ja simulointia.

Optimization of energy consumption in wastewater pumping

Pumppauksessa arvioidaan olevan niin teknisesti kuin taloudellisestikin huomattavia mahdollisuuksia säästää energiaa. Maailmanlaajuisesti pumppaus kuluttaa lähes 22 % sähkö-moottorien energiantarpeesta. Tietyillä teollisuudenaloilla jopa yli 50 % moottorien käyttämästä sähköenergiasta voi kulua pumppaukseen. Jäteveden pumppauksessa pumppujen toiminta perustuu tyypillisesti on-off käyntiin, jolloin pumpun ollessa päällä se käy täydellä teholla. Monissa tapauksissa pumput ovat myös ylimitoitettuja. Yhdessä nämä seikat johtavat kasvaneeseen energian kulutukseen. Työn teoriaosassa esitellään perusteet jätevesihuollosta ja jäteveden käsittelystä sekä pumppaussysteemin pääkomponentit: pumppu, putkisto, moottori ja taajuusmuuttaja. Työn empiirisessä osassa esitellään työn aikana kehitetty laskuri, jonka avulla voidaan arvioida energiansäästöpotentiaalia jäteveden pumppaussysteemeissä. Laskurilla on mandollista laskea energiansäästöpotentiaali käytettäessä pumpun tuoton ohjaustapana pyörimisnopeuden säätöä taajuusmuuttajalla on-off säädön sijasta. Laskuri ilmoittaa optimaalisimmanpumpun pyörimisnopeuden sekä ominaisenergiankulutuksen. Perustuen laskuriin, kolme kunnallista jätevedenpumppaamoa tutkittiin. Myös laboratorio-testitsuoritettiin laskurin simuloimiseksi sekä energiansäästöpotentiaalin arvioimiseksi. Tutkimukset osoittavat, että jätevedenpumppauksessa on huomattavia mandollisuuksia säästää energiaa pumpun pyörimisnopeutta pienentämällä. Geodeettisen nostokorkeuden ollessa pieni, voidaan energiaa säästää jopa 50 % ja pitkällä aikavälillä säästö voi olla merkittävä. Tulokset vahvistavat myös tarpeen jätevedenpumppaussysteemien toiminnan optimoimiseksi.

Osuustoiminnallisen yrityksen yhteiskuntavastuu - esimerkkinä suomalainen metsäteollisuus

Tämä Pro gradu -tutkielma osallistuu osuustoiminta- ja yhteiskuntavastuukeskusteluun yhdistämällä nämä kaksi käsitettä toisiinsa. Tavoitteena on kuvata osuustoiminnallisten arvojen ja periaatteiden heijastumista osuustoimintayritysten yhteiskuntavastuullisuuteen ja erityisesti yhteiskuntavastuusta raportointiin. Tutkimuson laadullinen tutkimus. Empiirinen aineisto koostuu kolmen metsäteollisuusyhtiön, yhden osuuskunnan ja kahden osakeyhtiön, yhteiskuntavastuuraporteista, vuosikertomuksista, Internet-sivuista ja yritysten yhteiskuntavastuuasiantuntijoille tehdyistä haastatteluista. Aineistoa kerättiin syksystä 2006 alkukevääseen 2007 asti. Tutkimustulokset ovat yhdenmukaisia aiemman tutkimuksenkanssa siinä, että osuustoimintayritysten arvot ja periaatteet ohjaavat yhteiskuntavastuulliseen toimintaan. Osuustoimintayritykset toimivat yhteiskuntavastuullisesti, mutta eivät viesti vastuullisuudestaan yhtä aktiivisesti kuin osakeyhtiöt. Maailman nykytilanteessa pehmeämmät arvot ovat alkaneet löytää entistä enemmän jalansijaa, ja vastuullisuus tulee jatkossa varmasti korostumaan liiketoiminnassa entistäkin enemmän. Osuustoimintayritykset voivatkin vastuuviestintää lisäämällä löytää vastuullisuudesta tulevaisuuden menestystekijän.

Kuitupakkausten konvertointilaitteet – nykytila ja kehitysnäkymät

Diplomityössä selvitettiin kartonkipakkausten konvertoimiseen käytettäviä laitteistoja ja niiden valmistajia. Tuote johon työssä keskityttiin, oli muovipinnoitetusta taivekartongista valmistettu kartonkivuoka. Työssä käsiteltiin ensin yleistä asiaa kartongeista ja niiden ominaisuuksista, jonka jälkeen esiteltiin kartonkivuokien konvertoimiseen käytettäviä menetelmiä. Menetelmistä työssä keskityttiin erityisesti leikkaukseen, nuuttaukseen ja muodonantoon. Leikkaus ja nuuttaus, eli stanssaus suoritetaan joko tasostanssilla, rotaatiostanssilla tai mallileikkurilla. Muodonanto suoritetaan prässäämällä tai taivuttamalla käyttäen vuoanmuodostajaa. Näistä prässääminen soveltuu paremmin primääripakkauksena toimivan vuoan muodostamiseen. Nykyaikaisissa prässeissä muovaavia työkalupareja voi olla yhdestä viiteen kappaletta. Työssä oli vertailuosio, jossa pistemenetelmän avulla pisteytettiin neljä erilaista linjavaihtoehtoa. Vertailussa painotettiin tuotantokapasiteettia, linjan yleistä joustavuutta, sekä joustavuutta häiriön sattuessa. Vertailussa korkeimman pistemäärän sai laite, jossa samaan laitteeseen on yhdistetty stanssaus ja muodonanto. Jos aihionsiirto saadaan luotettavasti automatisoitua, on tulevaisuuden linjavaihtoehdoissa varteenotettava vaihtoehto linja, jossa tasostanssi hoitaa leikkauksen ja nuuttauksen, ja tämän jälkeen prässääviä laitteita on useampi kappale. Myös mallileikkuri on varteenotettava vaihtoehto osaksi vuoan valmistuslinjaa, jos sen nopeutta saadaan nostettua.

Characterisation of Laser Beam and Paper Material Interaction

It is known already from 1970´s that laser beam is suitable for processing paper materials. In this thesis, term paper materials mean all wood-fibre based materials, like dried pulp, copy paper, newspaper, cardboard, corrugated board, tissue paper etc. Accordingly, laser processing in this thesis means all laser treatments resulting material removal, like cutting, partial cutting, marking, creasing, perforation etc. that can be used to process paper materials. Laser technology provides many advantages for processing of paper materials: non-contact method, freedom of processing geometry, reliable technology for non-stop production etc. Especially packaging industry is very promising area for laser processing applications. However, there are only few industrial laser processing applications worldwide even in beginning of 2010´s. One reason for small-scale use of lasers in paper material manufacturing is that there is a shortage of published research and scientific articles. Another problem, restraining the use of laser for processing of paper materials, is colouration of paper material i.e. the yellowish and/or greyish colour of cut edge appearing during cutting or after cutting. These are the main reasons for selecting the topic of this thesis to concern characterization of interaction of laser beam and paper materials. This study was carried out in Laboratory of Laser Processing at Lappeenranta University of Technology (Finland). Laser equipment used in this study was TRUMPF TLF 2700 carbon dioxide laser that produces a beam with wavelength of 10.6 μm with power range of 190-2500 W (laser power on work piece). Study of laser beam and paper material interaction was carried out by treating dried kraft pulp (grammage of 67 g m-2) with different laser power levels, focal plane postion settings and interaction times. Interaction between laser beam and dried kraft pulp was detected with different monitoring devices, i.e. spectrometer, pyrometer and active illumination imaging system. This way it was possible to create an input and output parameter diagram and to study the effects of input and output parameters in this thesis. When interaction phenomena are understood also process development can be carried out and even new innovations developed. Fulfilling the lack of information on interaction phenomena can assist in the way of lasers for wider use of technology in paper making and converting industry. It was concluded in this thesis that interaction of laser beam and paper material has two mechanisms that are dependent on focal plane position range. Assumed interaction mechanism B appears in range of average focal plane position of 3.4 mm and 2.4 mm and assumed interaction mechanism A in range of average focal plane position of 0.4 mm and -0.6 mm both in used experimental set up. Focal plane position 1.4 mm represents midzone of these two mechanisms. Holes during laser beam and paper material interaction are formed gradually: first small hole is formed to interaction area in the centre of laser beam cross-section and after that, as function of interaction time, hole expands, until interaction between laser beam and dried kraft pulp is ended. By the image analysis it can be seen that in beginning of laser beam and dried kraft pulp material interaction small holes off very good quality are formed. It is obvious that black colour and heat affected zone appear as function of interaction time. This reveals that there still are different interaction phases within interaction mechanisms A and B. These interaction phases appear as function of time and also as function of peak intensity of laser beam. Limit peak intensity is the value that divides interaction mechanism A and B from one-phase interaction into dual-phase interaction. So all peak intensity values under limit peak intensity belong to MAOM (interaction mechanism A one-phase mode) or to MBOM (interaction mechanism B onephase mode) and values over that belong to MADM (interaction mechanism A dual-phase mode) or to MBDM (interaction mechanism B dual-phase mode). Decomposition process of cellulose is evolution of hydrocarbons when temperature is between 380- 500°C. This means that long cellulose molecule is split into smaller volatile hydrocarbons in this temperature range. As temperature increases, decomposition process of cellulose molecule changes. In range of 700-900°C, cellulose molecule is mainly decomposed into H2 gas; this is why this range is called evolution of hydrogen. Interaction in this range starts (as in range of MAOM and MBOM), when a small good quality hole is formed. This is due to “direct evaporation” of pulp via decomposition process of evolution of hydrogen. And this can be seen can be seen in spectrometer as high intensity peak of yellow light (in range of 588-589 nm) which refers to temperature of ~1750ºC. Pyrometer does not detect this high intensity peak since it is not able to detect physical phase change from solid kraft pulp to gaseous compounds. As interaction time between laser beam and dried kraft pulp continues, hypothesis is that three auto ignition processes occurs. Auto ignition of substance is the lowest temperature in which it will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. Three auto ignition processes appears in range of MADM and MBDM, namely: 1. temperature of auto ignition of hydrogen atom (H2) is 500ºC, 2. temperature of auto ignition of carbon monoxide molecule (CO) is 609ºC and 3. temperature of auto ignition of carbon atom (C) is 700ºC. These three auto ignition processes leads to formation of plasma plume which has strong emission of radiation in range of visible light. Formation of this plasma plume can be seen as increase of intensity in wavelength range of ~475-652 nm. Pyrometer shows maximum temperature just after this ignition. This plasma plume is assumed to scatter laser beam so that it interacts with larger area of dried kraft pulp than what is actual area of beam cross-section. This assumed scattering reduces also peak intensity. So result shows that assumably scattered light with low peak intensity is interacting with large area of hole edges and due to low peak intensity this interaction happens in low temperature. So interaction between laser beam and dried kraft pulp turns from evolution of hydrogen to evolution of hydrocarbons. This leads to black colour of hole edges.

Gelatin as an additive in bio-based barrier films

The main objective of the present study was to verify the approach on starch-gelatin blending for the paperboard coating formulations with enhanced barrier and mechanical properties. Based on that, another objective was to find out, how the approach will function with wood-based polysaccharides (CMC, EHEC and HPC) by analyzing their barrier properties and convertibility. The last objective was to find out, if pigments can be used in the composition of polysaccharide-protein blends without causing any negative effect on stated properties. The whole process chain of the barrier coating development was studied in the research. The methodology applied included pilot-scale coating and converting trials for the evaluation of mechanical properties of obtained coatings, namely their exposure to cracking with the loss of barrier properties. The results obtained indicated that the combination of starch with gelatin, in fact, improves the grease barrier properties and flexibility of starch-based coatings, thereby confirming the offered approach. The similar results were obtained for CMC, exhibited elevated barrier properties and surface coverage, proving that the approach also functions with wood-based polysaccharides. The introduction of equal amounts of talc gave various effects at different gelatin dosages on barrier properties of wood-based polysaccharides. Mainly, the elevation of grease barrier properties was observed. The convertibility of talc-filled coatings was not sufficient.

Henkilöstöraportointi strategisen henkilöstöjohtamisen tukena - Case Eteva kuntayhtymä

Organisaatiot kohtaavat jatkuvasti uusia ja vaativia haasteita. Organisaatiot tarvit-sevat henkilöstön asiantuntemusta ja osaamista, jotta voisivat menestyä kaiken aikaa kovenevassa kilpailutilanteessa. Henkilöstön osaaminen, tiedot ja taidot on tunnistettu organisaation tärkeimmäksi voimavaraksi. Tämän tutkimuksen tavoit-teena oli selvittää, millaista tietoa henkilöstä organisaatiossa johtamis- ja esimies-työtä tekevät tarvitsevat strategisen henkilöstöjohtamisen tueksi. Tutkimus suoritettiin tapaustutkimuksena kehitysvammapalveluja tuottavassa or-ganisaatiossa. Empiirinen aineisto kerättiin ja analysoitiin määrällisin menetelmin kyselytutkimuksena. Analysoinnissa käytettiin lisäksi sisällön analyysia. Tutki-muskysely kohdennettiin kohdeorganisaatiossa johtamis- ja esimiestyötä tekevil-le. Kohdeorganisaation johtamis- ja esimiestyötä tekevät tarvitsevat strategisen hen-kilöstöjohtamisen tueksi monipuolista laadullista ja määrällistä tietoa henkilöstös-tä ja taloudesta sekä palautetta oman esimiestyön laadusta. Tieto henkilöstön työhyvinvoinnista ja työtyytyväisyydestä koettiin tärkeäksi. Tuotetut tiedot tulisi olla saatavissa yhdestä paikasta. Esimiehet tarvitsevat myös osaamisen vahvistamista tuotetun tiedon tulkintaan ja käsittelyyn.

Sustainable Development – the Key to Competitiveness CSR as an added value to Alstom’s corporate performance

Corporate social responsibility or CSR is today a widely recognized concept which is receiving in- creasing popularity extremely rapidly, especially in the business world. The pressure on companies to carry out their business practices in ethical manners, which promote the wellbeing of the environment and society, is coming from all directions and all stakeholders. Alstom, a French multinational conglomerate operating in the rail transport and energy industry, is no exception to this norm. This company, which will be used as the case example in this thesis, is being brought to bay in terms of engaging in CSR practices and practicing business with high ethics. It is surely not a negatively conceived phenomenon that CSR is being put on a pedestal – quite the opposite. Instead of corporations practicing CSR only to meet their stakeholder requirements through practicing window dressing, many corporations actually strive to benefit from the practice of corporate social business. In addition to bringing benefit to externals a corporation such as Alstom itself can benefit from being involved in CSR. The purpose of this thesis is to evaluate the current strategic values and the future perspectives of CSR at Alstom and moreover the added value which the practice of CSR could bring Alstom as a business. A set of perspectives from a futures studies viewpoint is looked at, with critical examination of the company’s current corporate practices as well as the CSR related studies and theories written for corporations. Through this, some solutions and practices will be suggested to Alstom in order for it to fully utilize the potential of corporate social business and the value it can bring in the most probable futures that the company is expected to face. By utilizing the Soft Systems Methodology (SSM), a method mainly used in organizations to solve problematic issues in management and policy contexts, a process is developed to see what improvements could be of help in improving Alstom and its way towards involving CSR in its business practices even more than it currently does. Alstom is already deeply involved in the practicing of CSR and its vision has a strong emphasis on this popular concept of today. In order to stay in the game and to use CSR as a competitive advantage to the company, Alstom ought to embed corporate social practices even deeper in its organizational culture by using them as a tool to reduce risk and costs, increasing employee commitment and customer loyalty and to attract socially responsible investors, just to name a few. CSR as a concept is seen to have great potential in the future, an opportunity Alstom will not miss.

Press forming of paperboard – advancement of converting tools and process control

Press forming is nowadays one of the most common industrial methods in use for producing deeper trays from paperboard. Demands for material properties like recyclability and sustainability have increased also in the packaging industry, but there are still limitations related to the formability of paperboard. A majority of recent studies have focused on material development, but the potential of the package manufacturing process can also be improved by the development of tooling and process control. In this study, advanced converting tools (die cutting tools and the press forming mould) are created for production scale paperboard tray manufacturing. Also monitoring methods that enable the production of paperboard trays with enhanced quality, and can be utilized in process control are developed. The principles for tray blank preparation, including creasing pattern and die cutting tool design are introduced. The mould heating arrangement and determination of mould clearance are investigated to improve the quality of the press formed trays. The effect of the spring back of the tray walls on the tray dimensions can be managed by adjusting the heat-related process parameters and estimating it at the mould design stage. This enables production speed optimization as the process parameters can be adjusted more freely. Real-time monitoring of pressing force by using multiple force sensors embedded in the mould structure can be utilized in the evaluation of material characteristics on a modified production machinery. Comprehensive process control can be achieved with a combination of measurement of the outer dimensions of the trays and pressing force monitoring. The control method enables detection of defects and tracking changes in the material properties. The optimized converting tools provide a basis for effective operation of the control system.

Monopoly power, trade protection and growth: cross industry evidence

This paper investigates the impact of monopoly power on trade policy. Annual panel-databases of Brazilian industries for the years 1988 through 1994 were used. The regressions reported here are robust to openness indicator, concentration index, control variables and sample size, and suggest that industries with higher monopoly power are more protected than competitive sectors. In the period of study the country experienced a major trade liberalization, but the results in the paper show that the reduction in protection was smaller in sectors with higher monopoly power. We thus have evidence favoring recent growth literature which stresses that interest groups with control over creasing productivity. The results here confirm the first part of this argument and show that organized groups in fact are able to obtain policy advantages that reduce competition.

Valor nutritivo da leguminosa Flemingia macrophylla (Willd.) Merrill para suplementação alimentar de ruminantes na Amazônia Oriental

O conhecimento do valor nutritivo de plantas forrageiras é de grande relevância quando se pretende elevar a produtividade dos sistemas pecuários na Amazônia Oriental, principalmente em áreas onde ocorre deficiência de forragem de boa qualidade, em períodos de déficit hídrico. Assim, caracterizar a potencialidade da leguminosa Flemingia macrophylla (Willd.) Merrill, como alternativa para alimentação animal, assume relevante importância, pois pode influenciar no desempenho produtivo de bovídeos para carne e leite. Dessa forma, esta pesquisa visou avaliar a composição química, digestibilidade aparente e consumo voluntário dessa leguminosa na alimentação suplementar de ruminantes, em períodos de reduzida disponibilidade de forragem, de baixo valor nutritivo. O trabalho foi realizado na Embrapa Amazônia Oriental, em Belém-Pará, (1º28´ S 48º27´ W de Greenwich). Foram determinadas as características nutricionais da leguminosa, durante um período de 21 dias, com 16 ovinos, em gaiolas metabólicas individuais, distribuídas em delineamento inteiramente casualizado, em quatro tratamentos e quatro repetições, onde os tratamentos (T1, T2, T3 e T4) continham quicuio-da-amazônia (Brachiaria humidicola) e níveis crescentes de 100%, 75%, 50% e 25% de inclusão de F. macrophylla. Os teores de tanino na composição da dieta foram 1,37; 0,62; 0,31 e 0,17%, respectivamente. Os consumos de matéria seca, em g/dia e % do peso vivo, foram de 901,8 e 2,4; 947,9 e 2,5; 859,5 e 2,2; e 930,2 e 2,5 e de proteína bruta 232,4; 188,7; 132,1 e 107,6 g/dia. Os coeficientes de digestibilidade da matéria seca foram de 54,1; 59,2; 55,1; e 62,0%, da matéria orgânica de 57,3; 61,2; 57,6; e 64,0% e de proteína bruta de 63,2; 60,5; 51,4; 52,0%, respectivamente. A leguminosa possui potencial produtivo, com elevada disponibilidade de matéria seca, para ser utilizada como suplemento alimentar para ruminantes, principalmente em períodos críticos. Níveis de inclusão de F. macrophylla, em torno de 75%, possibilitam maior consumo da matéria seca, matéria orgânica, e das frações fibrosas e 100% permitem melhor consumo de PB e EB.

Sistemas de controle em domínios estratificados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Koproduktion von Wissen in der Entwicklung des Biolandbaus - Einflüsse von Marginalisierung, Anerkennung und Markt

The empirical analysis of the historical development of transdisciplinary co-production of knowledge (CPK) in organic agriculture (OA) in Switzerland has revealed three distinct phases. The initial phase shows various characteristics of transdisciplinary CPK and a high importance of experiential knowledge. The 2nd and 3rd phases involve an in-creasing segregation of farmers’, extension agents’, and scientists’ knowledge, caused by internal and external impacts, i.e. foundation of independent research institutions, changes in agriculture policy, and new market strategies. These developments strikingly represent an ambiguous trend: the growing societal and political recognition of OA and the increasing market, which are positive achievements, are associated by a gradual loss of very precious forms of CPK. A successful re-establishment of CPK processes and re-integration of experiential knowledge would help to resolve this dilemma and thus improve future research in OA and sustainability research in general.

Vibrations, Posture, and the Stabilization of Gaze: An Experimental Study on Impedance Control

Vibrations, Posture, and the Stabilization of Gaze: An Experimental Study on Impedance Control R. KREDEL, A. GRIMM & E.-J. HOSSNER University of Bern, Switzerland Introduction Franklin and Wolpert (2011) identify impedance control, i.e., the competence to resist changes in position, velocity or acceleration caused by environmental disturbances, as one of five computational mechanisms which allow for skilled and fluent sen-sorimotor behavior. Accordingly, impedance control is of particular interest in situa-tions in which the motor task exhibits unpredictable components as it is the case in downhill biking or downhill skiing. In an experimental study, the question is asked whether impedance control, beyond its benefits for motor control, also helps to stabi-lize gaze what, in turn, may be essential for maintaining other control mechanisms (e.g., the internal modeling of future states) in an optimal range. Method In a 3x2x4 within-subject ANOVA design, 72 participants conducted three tests on visual acuity and contrast (Landolt / Grating and Vernier) in two different postures (standing vs. squat) on a platform vibrating at four different frequencies (ZEPTOR; 0 Hz, 4 Hz, 8 Hz, 12 Hz; no random noise; constant amplitude) in a counterbalanced or-der with 1-minute breaks in-between. In addition, perceived exertion (Borg) was rated by participants after each condition. Results For Landolt and Grating, significant main effects for posture and frequency are re-vealed, representing lower acuity/contrast thresholds for standing and for higher fre-quencies in general, as well as a significant interaction (p < .05), standing for in-creasing posture differences with increasing frequencies. Overall, performance could be maintained at the 0 Hz/standing level up to a frequency of 8 Hz, if bending of the knees was allowed. The fact that this result is not only due to exertion is proved by the Borg ratings showing significant main effects only, i.e., higher exertion scores for standing and for higher frequencies, but no significant interaction (p > .40). The same pattern, although not significant, is revealed for the Vernier test. Discussion Apparently, postures improving impedance control not only turn out to help to resist disturbances but also assist in stabilizing gaze in spite of these perturbations. Con-sequently, studying the interaction of these control mechanisms in complex unpre-dictable environments seems to be a fruitful field of research for the future. References Franklin, D. W., & Wolpert, D. M. (2011). Computational mechanisms of sensorimotor control. Neuron, 72, 425-442.

On the motion planning & control of nonlinear robotic systems

In the last decades, we saw a soaring interest in autonomous robots boosted not only by academia and industry, but also by the ever in- creasing demand from civil users. As a matter of fact, autonomous robots are fast spreading in all aspects of human life, we can see them clean houses, navigate through city traffic, or harvest fruits and vegetables. Almost all commercial drones already exhibit unprecedented and sophisticated skills which makes them suitable for these applications, such as obstacle avoidance, simultaneous localisation and mapping, path planning, visual-inertial odometry, and object tracking. The major limitations of such robotic platforms lie in the limited payload that can carry, in their costs, and in the limited autonomy due to finite battery capability. For this reason researchers start to develop new algorithms able to run even on resource constrained platforms both in terms of computation capabilities and limited types of endowed sensors, focusing especially on very cheap sensors and hardware. The possibility to use a limited number of sensors allowed to scale a lot the UAVs size, while the implementation of new efficient algorithms, performing the same task in lower time, allows for lower autonomy. However, the developed robots are not mature enough to completely operate autonomously without human supervision due to still too big dimensions (especially for aerial vehicles), which make these platforms unsafe for humans, and the high probability of numerical, and decision, errors that robots may make. In this perspective, this thesis aims to review and improve the current state-of-the-art solutions for autonomous navigation from a purely practical point of view. In particular, we deeply focused on the problems of robot control, trajectory planning, environments exploration, and obstacle avoidance.