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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Robust Control For Gantry Cranes

Costa, Giuseppe, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 1999 (has links)
In this thesis a class of robust non-linear controllers for a gantry crane system are discussed. The gantry crane has three degrees of freedom, all of which are interrelated. These are the horizontal traverse of the cart, the vertical motion of the goods (i.e. rope length) and the swing angle made by the goods during the movement of the cart. The objective is to control all three degrees of freedom. This means achieving setpoint control for the cart and the rope length and cancellation of the swing oscillations. A mathematical model of the gantry crane system is developed using Lagrangian dynamics. In this thesis it is shown that a model of the gantry crane system can be represented as two sub models which are coupled by a term which includes the rope length as a parameter. The first system will consist of the cart and swing dynamics and the other system is the hoist dynamics. The mathematical model of these two systems will be derived independent of the other system. The model that is comprised of the two sub models is verified as an accurate model of a gantry crane system and it will be used to simulate the performance of the controllers using Matlab. For completeness a fully coupled mathematical model of the gantry crane system is also developed. A detailed design of a gain scheduled sliding mode controller is presented. This will guarantee the controller's robustness in the presence of uncertainties and bounded matched disturbances. This controller is developed to achieve cart setpoint and swing control while achieving rope length setpoint control. A non gain scheduled sliding mode controller is also developed to determine if the more complex gain scheduled sliding mode controller gives any significant improvement in performance. In the implementation of both sliding mode controllers, all system states must be available. In the real-time gantry crane system used in this thesis, the cart velocity and the swing angle velocity are not directly available from the system. They will be estimated using an alpha-beta state estimator. To overcome this limitation and provide a more practical solution an optimal output feedback model following controller is designed. It is demonstrated that by expressing the system and the model for which the system is to follow in a non-minimal state space representation, LQR techniques can be used to design the controller. This produces a dynamic controller that has a proper transfer function, and negates the need for the availability of all system states. This thesis presents an alternative method of solving the LQR problem by using a generic eigenvalue solution to solve the Riccati equation and thus determine the optimal feedback gains. In this thesis it is shown that by using a combination of sliding mode and H??? control techniques, a non-linear controller is achieved which is robust in the presence of a wide variety of uncertainties and disturbances. A supervisory controller is also described in this thesis. The supervisory control is made up of a feedforward and a feedback component. It is shown that the feedforward component is the crane operator's action, and the feedback component is a sliding mode controller which compensates as the system's output deviates from the desired trajectory because of the operator's inappropriate actions or external disturbances such as wind gusts and noise. All controllers are simulated using Matlab and implemented in real-time on a scale model of the gantry crane system using the program RTShell. The real-time results are compared against simulated results to determine the controller's performance in a real-time environment.
12

Robust Control For Gantry Cranes

Costa, Giuseppe, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 1999 (has links)
In this thesis a class of robust non-linear controllers for a gantry crane system are discussed. The gantry crane has three degrees of freedom, all of which are interrelated. These are the horizontal traverse of the cart, the vertical motion of the goods (i.e. rope length) and the swing angle made by the goods during the movement of the cart. The objective is to control all three degrees of freedom. This means achieving setpoint control for the cart and the rope length and cancellation of the swing oscillations. A mathematical model of the gantry crane system is developed using Lagrangian dynamics. In this thesis it is shown that a model of the gantry crane system can be represented as two sub models which are coupled by a term which includes the rope length as a parameter. The first system will consist of the cart and swing dynamics and the other system is the hoist dynamics. The mathematical model of these two systems will be derived independent of the other system. The model that is comprised of the two sub models is verified as an accurate model of a gantry crane system and it will be used to simulate the performance of the controllers using Matlab. For completeness a fully coupled mathematical model of the gantry crane system is also developed. A detailed design of a gain scheduled sliding mode controller is presented. This will guarantee the controller's robustness in the presence of uncertainties and bounded matched disturbances. This controller is developed to achieve cart setpoint and swing control while achieving rope length setpoint control. A non gain scheduled sliding mode controller is also developed to determine if the more complex gain scheduled sliding mode controller gives any significant improvement in performance. In the implementation of both sliding mode controllers, all system states must be available. In the real-time gantry crane system used in this thesis, the cart velocity and the swing angle velocity are not directly available from the system. They will be estimated using an alpha-beta state estimator. To overcome this limitation and provide a more practical solution an optimal output feedback model following controller is designed. It is demonstrated that by expressing the system and the model for which the system is to follow in a non-minimal state space representation, LQR techniques can be used to design the controller. This produces a dynamic controller that has a proper transfer function, and negates the need for the availability of all system states. This thesis presents an alternative method of solving the LQR problem by using a generic eigenvalue solution to solve the Riccati equation and thus determine the optimal feedback gains. In this thesis it is shown that by using a combination of sliding mode and H??? control techniques, a non-linear controller is achieved which is robust in the presence of a wide variety of uncertainties and disturbances. A supervisory controller is also described in this thesis. The supervisory control is made up of a feedforward and a feedback component. It is shown that the feedforward component is the crane operator's action, and the feedback component is a sliding mode controller which compensates as the system's output deviates from the desired trajectory because of the operator's inappropriate actions or external disturbances such as wind gusts and noise. All controllers are simulated using Matlab and implemented in real-time on a scale model of the gantry crane system using the program RTShell. The real-time results are compared against simulated results to determine the controller's performance in a real-time environment.
13

Standardization of a modular on-trackgantry system

Horn af Rantzien, Arvid, Björkdal, Casper January 2022 (has links)
This thesis is an investigation of how a modular on-track gantry system intendedfor arc-welding robots can be standardized by using the existing product portfolio ofon-track gantry systems of a company.The company in this thesis have chosen to be anonymous, and will be referred toas the company. The need for a standardized product is high, since robot solutionsis consistently becoming more prevalent in all industries year by year. They havethe ability to execute commands with precision for longer than any manual labourcould. To keep up with the demand for robot solution, the company is interestedin standardizing their current on-track gantry system to speed up their process.Standardizing is the process of developing and implementing specifications based onthe consensus of the views of firms, users, interest groups and governments. Thecompany currently customizes most of their on-track gantry systems but wants tostandardize this process.The purpose of this thesis is to propose and evaluate a standardized model of anon-track gantry system. This is done by dividing the work in three separate phases.One pertaining to collecting information about the on-track gantry. The followingphase involves processing the information and establishing a baseline for the model.The final phase is contains the creation of a new on-track gantry system that isconstructed from existing parts and and new parts and simulated regarding stressand frequency.The information that could be extracted from existing on-track gantry were anumber of parameters, such as stroke lengths, production costs, part numbers etc.From the information, a set of needs could also be established. Further, the infor-mation is processed by comparing how many different parts exists in the modules ofexisting on-track gantry. A decision is also done here with the help of two decisionanalyses, to choose the best existing gantry to base the standardized model on. Fi-nally, a proposed standardized model is constructed with a set 2 stroke lengths inz-direction, 1500 mm and 2000 mm and 3 stroke lengths in x-direction, 2000 mm,3000 mm and 4000 mm. The model also includes the option to choose whether anattached arc-welding robot is placed stiff in a position or if it should move the entireinterval in the z- and x-directions.In conclusion, the new proposed model is standardized due to there being a clearguideline for how the model is set up, what it can hold and the stroke lengths. / Den här tesen är en undersökning av hur ett modulärt on-track gantry system förbågsvetsrobotar kan standardiseras med hjälp av ett företags befintliga produktport-följ av gantry system för bågsvetsrobotar.Företaget har i denna avhandling valt att vara anonymt och kommer att benäm-nas företaget. Behovet av en standardiserad produkt är stort, eftersom robotlösningarständigt blir vanligare i alla branscher år för år. De har förmågan att utföra kom-mandon med precision under längre tid än vad manuellt arbete skulle kunna göra.För att hålla jämna steg med efterfrågan på robotlösningar är företaget intresserat avatt standardisera sitt nuvarande system med spårbundna gantry för att påskynda sinprocess. Standardisering är en process för att utveckla och genomföra specifikationersom bygger på en samsyn mellan företag, användare, intressegrupper och regeringar.Företaget anpassar för närvarande de flesta av sina gantry system på spåren, menvill standardisera denna process.Syftet med denna avhandling är att föreslå och utvärdera en standardiserad mod-ell av ett gantry system för spårbundna fordon. Detta görs genom att dela upp ar-betet i tre separata faser. En som gäller insamling av information om gantry. Denföljande fasen handlar om att bearbeta informationen och fastställa en grund förmodellen. Den sista fasen innehåller skapandet av ett nytt system för spårbundnagantry som konstrueras av befintliga delar och nya delar och simuleras med avseendepå belastning och frekvens.Den information som kunde utvinnas från befintliga spårbundna gantry var ettantal parametrar, såsom slaglängder, produktionskostnader, artikelnummer osv. Utifråninformationen kunde också en uppsättning behov fastställas. Vidare bearbetas in-formationen genom att jämföra hur många olika delar som finns i modulerna i debefintliga spårburna gantry. Här fattas också ett beslut med hjälp av två beslutsanal-yser för att välja den bästa befintliga gantry att basera den standardiserade modellenpå. Slutligen konstrueras en föreslagen standardiserad modell med två slaglängder iz-riktningen, 1500 mm och 2000 mm, och tre slaglängder i x-riktningen, 2000 mm,3000 mm och 4000 mm. Modellen innehåller också möjligheten att välja om enansluten bågsvetsrobot placeras styvt i en position eller om den ska förflytta sig helaintervallet i z- och x-riktningen.Sammanfattningsvis är den nya föreslagna modellen standardiserad tack vare attdet finns en tydlig riktlinje för hur modellen är uppbyggd, vad den kan hålla ochslaglängderna.
14

Konstrukce multifunkčního obráběcího centra / Design of multi-functional machining centre

Matěja, Josef January 2013 (has links)
The Diploma thesis deals with the design solution of multi-functional machining centre, especially with one of its parts – the design of the slide ram and vertical feed incl. the choice of convenient tool heads for the slide ram. The introducing part deals with the numerically controlled machines and centres generally, especially with the portal-type ones. It contains description of individual machine parts including examples of accessories from product plans of domestic and foreign producers. The second part of the Diploma thesis contains calculations and design solution of the slide ram and feed including the choice of the most suitable accessories applicable for this purpose. In the final phase the model of the slide ram has been introduced in the imersion virtual reality and integrated in the complete machine design. The Diploma thesis has been elaborated using the relevant technical literature.
15

Konstrukce multifunkčního obráběcího centra / Design of multi-functional machining centre

Cvejn, Jiří January 2013 (has links)
The purpose of this diploma thesis is a design of frame, crossbar, transverse feed, sliding feed of multifunctional machining center. In the first part, there is a brief research of history of machine tool conducted, division of machining centers, materials for frame construction, alternatives of drives of sliding axis. Further, I carry out an analysis of parameters of compeeting machine tools, from which I selected the parameters of our machine. Frame project of the machine, propulsion of axis X and Y, kinematic connection of axis X,Y,Z. Frame of machine is analysed by Finite Element Method. Over the scope of this work I suggest a solution for covering of linear axis as well as their measuring of actual position. 3D model of frame and drives of machine are included in this work. A complete formation has been introduced into the immersive virtual reality environment.
16

Konstrukce multifunkčního obráběcího centra / Design of multi-functional machining centre

Neumann, Ondřej January 2013 (has links)
Design of multi-functional machining center The purpose of this diploma thesis is a design of turning table for multi-functional machining center. The first part is the background research of multi-functional machining centers, rotary tables, chip management and brief overview of chosen machining center’s manufacturers. The sphere of using of the designed machine, including parameters of turning table, and its basic parameters are determined on the basis of this research. Afterwards, the variants of turning table drives are drawn up and one variant of calculation and construction is made. Design of clamping desk and chip management of the machine is also made. Above a specified framework of this thesis, simplified machine foundation design and anchoring of machine parts to this basis is performed. The work also includes a 3D model of turning table and substructure. The complete set of constructed machining center was brought into immersion virtual reality environment.
17

Jeřáb radiální portálový / Radial gantry crane

Dias, Aleš January 2016 (has links)
The aim of my thesis is a conceptual design radial gantry crane including the important strength calculations according to the standards and examinations by means of ANSYS Workbench. The lifting capacity is 1500 kg, the length of the boom is 12 000 mm and the height of lifting is 3600mm. The crane is designed as fully revolving and the angle turning is 360°. The work also includes the selection of a suitable lifting gear from the manufacturer´s catalogue including the accessories casters, all important components and also FEM construction analysis.
18

Radiotherapy Beamline Design for Laser-driven Proton Beams

Masood, Umar 10 October 2019 (has links)
Motivation: Radiotherapy is an important modality in cancer treatment commonly using photon beams from compact electron linear accelerators. However, due to the inverse depth dose profile (Bragg peak) with maximum dose deposition at the end of their path, proton beams allow a dose escalation within the target volume and reduction in surrounding normal tissue. Up to 20% of all radiotherapy patients could benefit from proton therapy (PT). Conventional accelerators are utilized to obtain proton beams with therapeutic energies of 70 – 250 MeV. These beams are then transported to the patient via magnetic transferlines and a rotatable beamline, called gantry, which are large and bulky. PT requires huge capex, limiting it to only a few big centres worldwide treating much less than 1% of radiotherapy patients. The new particle acceleration by ultra-intense laser pulses occurs on micrometer scales, potentially enabling more compact PT facilities and increasing their widespread. These laser-accelerated proton (LAP) bunches have been observed recently with energies of up to 90 MeV and scaling models predict LAP with therapeutic energies with the next generation petawatt laser systems. Challenges: Intense pulses with maximum 10 Hz repetition rate, broad energy spectrum, large divergence and short duration characterize LAP beams. In contrast, conventional accelerators generate mono-energetic, narrow, quasi-continuous beams. A new multifunctional gantry is needed for LAP beams with a capture and collimation system to control initial divergence, an energy selection system (ESS) to filter variable energy widths and a large acceptance beam shaping and scanning system. An advanced magnetic technology is also required for a compact and light gantry design. Furthermore, new dose deposition models and treatment planning systems (TPS) are needed for high quality, efficient dose delivery. Materials and Methods: In conventional dose modelling, mono-energetic beams with decreasing energies are superimposed to deliver uniform spread-out Bragg peak (SOBP). The low repetition rate of LAP pulses puts a critical constraint on treatment time and it is highly inefficient to utilize conventional dose models. It is imperative to utilize unique LAP beam properties to reduce total treatment times. A new 1D Broad Energy Assorted depth dose Deposition (BEAD) model was developed. It could deliver similar SOBP by superimposing several LAP pulses with variable broad energy widths. The BEAD model sets the primary criteria for the gantry, i.e. to filter and transport pulses with up to 20 times larger energy widths than conventional beams for efficient dose delivery. Air-core pulsed magnets can reach up to 6 times higher peak magnetic fields than conventional iron-core magnets and the pulsed nature of laser-driven sources allowed their use to reduce the size and weight of the gantry. An isocentric gantry was designed with integrated laser-target assembly, beam capture and collimation, variable ESS and large acceptance achromatic beam transport. An advanced clinical gantry was designed later with a novel active beam shaping and scanning system, called ELPIS. The filtered beam outputs via the advanced gantry simulations were implemented in an advanced 3D TPS, called LAPCERR. A LAP beam gantry and TPS were brought together for the first time, and clinical feasibility was studied for the advanced gantry via tumour conformal dose calculations on real patient data. Furthermore, for realization of pulsed gantry systems, a first pulsed beamline section consisting of prototypes of a capturing solenoid and a sector magnet was designed and tested at tandem accelerator with 10MeV pulsed proton beams. A first air-core pulsed quadrupole was also designed. Results: An advanced gantry with the new ELPIS system was designed and simulated. Simulated results show that achromatic beams with actively selectable beam sizes in the range of 1 – 20 cm diameter with selectable energy widths ranging from 19 – 3% can be delivered via the advanced gantry. ELPIS can also scan these large beams to a 20 × 10 cm2 irradiation field. This gantry is about 2.5 m in height and about 3.5 m in length, which is about 4 times smaller in volume than the conventional PT gantries. The clinical feasibility study on a head and neck tumour patient shows that these filtered beams can deliver state-of-the-art 3D intensity modulated treatment plans. Experimental characterization of a prototype pulsed beamline section was performed successfully and the synchronization of proton pulse with peak magnetic field in the individual magnets was established. This showed the practical applicability and feasibility of pulsed beamlines. The newly designed pulsed quadrupole with three times higher field gradients than iron-core quadrupoles is already manufactured and will be tested in near future. Conclusion: The main hurdle towards laser-driven PT is a laser accelerator providing beams of therapeutic quality, i.e. energy, intensity, stability, reliability. Nevertheless, the presented advanced clinical gantry design presents a complete beam transport solution for future laser-driven sources and shows the prospect and limitations of a compact laser-driven PT facility. Further development in the LAP-CERR is needed as it has the potential to utilize advanced beam controls from the ELPIS system and optimize doses on the basis of advanced dose schemes, like partial volume irradiation, to bring treatment times further down. To realize the gantry concept, further research, development and testing in higher field and higher (up to 10 Hz) repetition rate pulsed magnets to cater therapeutic proton beams is crucial.
19

Röntgensjuksköterskans upplevelse av att arbeta med sliding gantry datortomografi : En intervjustudie / The radiographers experience of working with sliding gantry computed tomography : An interview study

Eriksson, Sofie, McGraw-Alcock, Tyler January 2023 (has links)
Introduktion: Röntgenmottagningen på Universitetssjukhuset i Örebro (USÖ) undersökertraumapatienter med sliding gantry datortomografi (SGDT). I ett SGDT-system står bordet fastpå plats och det är istället gantryt som rör sig över patienten under bildtagningen. Detta öppnarupp för möjligheten till ett nytt arbetssätt vilket kan påverka både röntgensjuksköterskor ochpatienten. Syfte: Syftet med studien är att undersöka hur SGDT påverkar röntgensjuksköterskans arbete vidtrauma och akutverksamhet. Underlättar SGDT arbetsflödet för röntgensjuksköterskor? I sådanafall hur? Metod: Studien utfördes som en kvalitativ studie med semistrukturerade intervjuer. Tioröntgensjuksköterskor deltog i studien. För att koda material och skapa tema gjordes en kvalitativinnehållsanalys. Resultat: Fördelar med SGDT är att arbetsflödet blivit smidigare eftersom det finns en tydligareroll i traumarummet, det är bättre organiserat, samarbetet med traumateamet har blivit bättre ochröntgensjuksköterskorna återgår fortare till normala akutflödet. Nackdelen med SGDT är att detinte är anpassad till ett vanligt akutflöde på USÖ. Slutsats: SGDT underlättar arbetsflödet för röntgensjuksköterskan vid en traumasituation med ettförbättrat samarbete, kommunikation och organisering. Dock är SGDT inte optimal för detvanliga akuta flödet. / Introduction: The department of radiology at Örebro University Hospital (USÖ) examinestrauma patients with sliding gantry computed tomography (SGDT). A SGDT system incorporatesa stationary examination table with a gantry that passes over the patient during scanning. Thisnovel method has the potential to affect both the radiographer as well as patient care. Aim: The aim of the study is to ascertain how SGDT affects the work of radiographers in traumaand emergency care. Does a SGDT facilitate an improved workflow for radiographers? If so,how? Method: The study used a qualitative design with semi-structured interviews. Ten radiographersfrom USÖ participated in the study. A qualitative content analysis was performed to create codesand themes from the collected materials. Results: The foremost benefit of SGDT is that the radiographers’ workflow improved. This isdue to a clearer role in the trauma suite, improved organisation, better interprofessionalcooperation with the trauma team and the ability to return more quickly to regular acuteexaminations. A drawback with SGDT is that it is suboptimal for normal acute examinations. Conclusion: SGDT facilitates a better workflow for radiographers in trauma examinationsbecause of improved coordination, communication and organisation, with few drawbacks.
20

The numerical simulation of wheel loads on an electric overhead travelling crane

McKenzie, Kim Anne 12 1900 (has links)
Thesis (MEng (Civil Engineering))--University of Stellenbosch, 2007. / The failure rate of electric overhead travelling crane supporting structures across the world is unacceptably high. Failures occur even when the supporting structures are designed within the relevant design codes. This demonstrates a lack of understanding of the dynamic behaviour of cranes in many design codes. The current South African loading code is simplistic with respect to crane supporting structure design, relying on empirical factors to determine the correct loads. While these factors lead to predicted forces in the correct range of values, the Eurocode’s methods are more scientifically based. In recognition of this the draft South African code predominantly incorporates the methods used by the Eurocode to calculate design forces for crane supporting structures. The purpose of this thesis was to use an existing numerical model to determine the wheel loads induced by a crane into the crane supporting structure through hoisting, normal longitudinal travel, skewing and rail misalignment. The numerically obtained forces were then compared with the design forces estimated in the current South African code and the Eurocode, in order to determine whether the factors and methods used in the codes are accurate. The current empirically based South African code was found to be highly conservative. In contrast the scientifically based design forces from the Eurocode were close to the numerically calculated forces, only failing to predict the behaviour of the crane in the case of skewing. Further work needs to be completed in the estimation of forces induced during this load case. Once this is achieved it is hoped that the better understanding of the crane forces adapted from the Eurocode into the draft South African code will lead to a reduction in failures of electric overhead travelling crane supporting structures.

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