To see the other types of publications on this topic, follow the link: Mechanically operated.
Dissertations / Theses on the topic 'Mechanically operated'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 36 dissertations / theses for your research on the topic 'Mechanically operated.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Gustafsson, Tapper Michael. "Operator Feedback." Thesis, KTH, Maskinkonstruktion (Inst.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232505.
Full textAbstract:
Det här är en rapport som sammanfattar ett examensarbete av studenten Michael GustafssonTapper skriven under våren 2018. Examensarbetet är en del av mastern Integreradproduktutveckling inom spåret Teknisk design på KTH, Kungliga Tekniska Högskolan iStockholm, Sverige. Dagens montörer i monteringsliner i fabriker får sin feedback från sinaverktyg men ibland missas denna information av montörerna. Det här examensarbetetresulterade i en vidareutveckling av ett tidigare projekt in kursen MF2016 Industriell design högrekurs, del 2. Resultatet var en lösning av ett par skyddsglasögon vid namn Protective SignalProvider eller PSP inom produktfamiljen Operator Feedback, OPF. PSP använde ljus från LEDlamporoch ljudvågor i form av vibrationer från benöverförande högtalare. En mer utförligundersökning gjordes också för att para den PSP med Atlas Copcos monteringssystem controllerPF6000. PSP använde sig av Bluetooth low energy för kommunikation och kan anslutas tillverktyget och till monteringens gränssnitt. En utvärdering jämförde den tidigare externaprodukten som kunde fästas på ett par skyddsglasögon med den nya produkten med integreradekomponenter. Utvärderingen resulterade i att den externa produkten skulle bli den bästalösningen för Atlas Copco att fortsätta med eftersom regleringar, lagar och standarder gör PSPför komplex att producera.<br>This report is a document summarizing a master thesis by the student Michael GustafssonTapper written during the spring of 2018. The thesis is the part of the master Integrated ProductDesign in the field of Industrial Design engineering at KTH, The Royal Institute of Technologyin Stockholm, Sweden. Today workers in assembly lines get feedback from their tools, butsometimes this transmitted information is missed by the worker. This thesis resulted in adevelopment of a previous project in the course MF2016 Industrial Design Engineering AdvancedCourse, Part 2. The result was a solution with a pair of safety glasses by the name Protective SignalProvider or PSP within the product family Operator Feedback, OPF. PSP used light of LEDsand soundwaves in form of vibration from bone conductive speakers. A more extensiveinvestigation was also done to pair PSP to Atlas Copco’s assembly system controller PF6000. ThePSP used Bluetooth low energy for communication and can be connected to the tool in use andthe interface of the assembly. An evaluation compared the previous external product that couldbe placed on a pair of safety glasses with the new internal product with integrated components.The evaluation resulted in the external product being the best solution for Atlas Copco toproceed with since regulations, laws and standards make PSP too complex to produce.
2
Rustrian, Wilmer. "Modeling of a small Remotely Operated Underwater Vehicle for autonomous navigation and control." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10102603.
Full textAbstract:
<p> Small scale unmanned underwater vehicles provide an opportunity to safely and efficiently complete tasks such as boat hull inspection and subsea development survey. These Remotely Operated Vehicles (ROVs) can be made more efficient if navigating underwater autonomously. This requires the development of highly accurate navigation and control algorithms, which, in turn, require a high-fidelity dynamic model of the vehicle based on first principles and validated by empirical data.</p><p> In this thesis, a simulation of a dynamics model for a commercially available ROV is developed. Empirical data from open-loop testing is used to generate a second-order transfer function using system identification to validate the simulation model. The transient response characteristics of the experimentally generated transfer function are then utilized to fine-tune the physical parameters in the simulation model. Finally, autopilot systems are designed using classical control theory to enable autonomous control over the attitudes and depth of the underwater vehicle.</p>
3
De, Smidt Roger. "Development of the power distribution system and communications hub for an underwater remotely operated vehicle." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13229.
Full textAbstract:
Includes bibliographical references.<br>This report details the research, design, development and testing of the third generation underwater remotely operated vehicle (ROV) produced by the University of Cape Town’s Robotics and Agents Research Laboratory (RARL). The ROV was designed and built in response to a request from the Department of Zoology for an ROV to aid their oceanic research. The two generations that had gone before this ROV had provided the research group with good experience, but a new vehicle was required that would offer a more robust research tool for the zoologists and a more versatile platform for future development within the RARL. ROV System Together with project partner Thomas Knight, a new ROV design was developed that was based on the open frame designs commonly used on commercially available ROVs. The ROV was to be propelled by five individual thruster modules and carried four high-powered LED light modules to provide lighting for the ROV’s forward and aft video cameras. In order to navigate the ROV a sonar unit was also incorporated on board. In order to provide power and communications from the surface station to each of the modules on board the ROV, distribution systems for each were required. As the project progressed, it became clear that these distribution systems were critical to the reliability and versatility of the vehicle and became the focus of the author’s scope. The report starts with a description of the design process that resulted in the decision to design a new ROV and then a brief description is provided of the ROV systems incorporated in the final design. The detailed design of the power and communications distribution systems is then presented using a bottom-up design approach, starting with the distribution of power and communications on board the ROV. Brief descriptions of the major components in these systems follow below. Electronics Pod The Electronics Pod (E-Pod) was designed to distribute power to each module on the ROV at the required voltages and currents, and to distribute serial communications to each module over an RS- 485 multi-drop network. The E-Pod incorporated two microcontrollers that were used to control the switching of power to each of the modules and were also connected on the RS-485 communications network. This RS-485 network was connected to the surface via an optical fibre link in the ROV’s tether, and the two converters required to establish this link were also housed in the E-Pod. Video feeds from the on-board cameras were fed into an encoder in the E-Pod and transmitted to the surface controller also via the fibre link. The power required by the E-Pod was drawn from the Power Pod on the ROV, which is described below. Power Pod The Power Pod was designed to convert the 400 VDC supply from the tether into 5 V, 12 V, 15 V and 48 V, which were required by the E-Pod. A total of 1.66kW was to be supplied to the E-Pod so compact, high-power DC-DC converters were integrated into the design of custom-made printed circuit boards (PCBs) in order to provide the required power. Currents sensors, temperature sensors and voltage level sensors were incorporated in the Power Pod circuitry. A microcontroller in the Power Pod was used to read all of the sensors and communicate the values to the surface controller via the E-Pod. Subsea Junction Box Because the ROV’s tether contained copper cores for power transmission and optical fibres for communications transmission, a very expensive hybrid subsea connector was required if it was to plug directly into the Power Pod or E-Pod. A junction box was therefore designed in which the copper cores of tether were separated from the optical fibres. The copper cores were fed to the Power Pod and the optical fibres to the E-Pod. The junction box was filled with oil and pressure compensated to reduce the risk of water ingress. Surface Power Supply Unit Including power losses in the distribution system, 2kW of power was required to be supplied to the tether. A surface power supply unit (PSU) was designed with an isolated, ungrounded 400 VDC power supply, which ran off a standard 230 V, 16 A mains supply. Start and emergency-stop switches were provided on the PSU enclosure, as well as a lockable isolator. The PSU incorporated an Ethernet network switch and fibre optic media converter to provide the link necessary between the tether and the laptop running the user interface and sonar software.
4
Ogundiran, John Olaoluwa. "Hydrodynamic added mass determination and attitude estimation of the Seahog - a remotely-operated underwater vehicle." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30953.
Full textAbstract:
The Seahog, which is an underwater Remotely-Operated Vehicle (ROV) was initiated to meet objectives set in conjunction with the marine biology group at the University of Cape Town for observation and light sample material collection from shallow sea floors. Prior to the commencement of this project, the Seahog was in a state where the basic functional units such as the thrusters, cameras, lights and power and communication systems were tested and installed. A crucial unit was however missing: the localization sensing unit. Localization comprises of linear and angular position sensing. The attitude of an underwater vehicle is its angular position relative to an inertial frame. Using the standard format for underwater vehicles, these angles are typically known as roll (about an axis along the surge direction of the vehicle), pitch (about an axis along the sway direction of the vehicle) and yaw (about an axis along the heave direction of the vehicle). Attitude sensing can be achieved using inertial sensors. Due to the shortcoming associated with the gyroscope’s measurements in the long term and noise sensitivities associated with the accelerometer and magnetometer, the optimal attitude estimation of the Seahog required sensor fusion. The Seahog’s Inertial Measurement Unit (IMU) is a 9 degree of freedom (DOF) unit fitted with an embedded processor collectively referred to as the iNEMO. Due to the time-variant nature of the magnetic field around the Seahog owing to variations in the magnetic coupling-based thrusters, the magnetometer was excluded from usage in the sensor fusion. The performances of several sensor fusion filters for estimating attitude were observed through simulation results. Steady state conditions were assumed for all but one test scenario. This was deemed sufficient as the Seahog is a slow moving vehicle and an assumption of mostly steady state was applicable. The filters were the Extended Kalman Filter (EKF), the standard Unscented Kalman Filter (UKF), Spherical Simplex Unscented Kalman Filter (SS-UKF) and a quaternionbased Complementary Filter (CF). The basis of performance assessment was the Root Mean Square Error (RMSE) from each filter’s simulation result. In almost all test scenarios, the UKF produced the least RMSE, i.e. the most accurate attitude estimates over the test period, though the results were not significantly better than the EKF’s. Under non-accelerating conditions, the filters were found to estimate the tilt angles relatively accurately but drift was present in the yaw estimation especially when no rotation occurred about the yaw axis. Ultimately, the EKF was selected as the attitude filter for implementation on the Seahog as its performance was comparable to the UKF’s at the tested sampling frequency and its computational cost was significantly less than that of the UKF. The EKF was implemented on the iNEMO’s embedded processor and put through some tests to observe its performance. For yaw angle estimation the filter ultimately yielded a minimized drift rate of about 0.87 °/hr which was deemed sufficient. The filter performed exceedingly well for the roll and pitch angle estimation, providing accuracies well within the typical tilt angle (roll and pitch) accuracy of 1 ° [1]. Ultimately, under steady state conditions, while the iNEMO provided accurate estimates for the tilt angles, a gyrocompass was suggested as the best solution for yaw estimation as it is a compass unaffected by magnetic field variations. When a vehicle is undergoing an unsteady motion underwater, extra resistance is experienced by the vehicle. This resistance differs to the drag forces as it is independent of the vehicle’s relative velocity. This resistive force is known as the added mass. Added mass covers both the translational mass and the rotational moment of inertia. This can be viewed as the volume of fluid that a vehicle has to move aside while in motion. A Simulink-based simulation model of the Seahog had been previously developed. Its hydrodynamic models were based on results from SolidWorks’ simulations and existing empirical formulation [2]. The added mass values implemented in the simulation were estimated using available empirical data, though for the formulas to be applicable, an oversimplification of the Seahog’s geometry was performed. For this reason, a different approach to added mass estimation was considered. Added mass are typically estimated computationally using software programs like WAMIT or experimentally through captive measurement at a tow tank facility fitted with Planar-Motion Mechanism (PMM) equipment. There was no access to such a facility nor a budget to purchase a CFD package licence that could serve this purpose (these are usually expensive, where a typical licence could range in the US$ 1000s). Therefore another approach had to be considered for estimating the added masses. A simple free-decaying pendulumbased experimental procedure was proposed by Chin et al. [3]. This approach was firstly verified by comparing the experimental test results to the analytical results of simple cuboids. Then the experiment was performed on a scaled version of the Seahog called the mini-ROV. Least square regression was employed in the MATLABbased algorithm used in processing the angular position data, which ultimately outputs the translational added mass. Finally, a tilt unit controller for setting the angular position of the front camera and light tray was designed, tested and installed on the Seahog. Its motor-to-tray torque transmission was magnetic coupling-based as this solution offered a safer and more durable option when compared with the dynamic sealing solution.
5
Azamfirei, Victor, and Navarro Luis Donaldo Preciado. "Interface Design for Driver Operated Control Systems." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-13899.
Full text
6
Raju, G. Jagannath. "Operator adjustable impedance in bilateral remote manipulation." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14445.
Full text
7
Rust, Ian Charles. "The Eyeball ROV : an underwater Remotely Operated Vehicle featuring advances in rotational actuation, communication, and localization." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68953.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 101-103).<br>The design for a spherical Remotely Operated Vehicle (ROV) with a camera, called the Eyeball ROV due to motions similar to the human eye, is presented in this thesis. The ROV features an actuation scheme that utilizes a two-axis gimbal for changing the location of the center of mass of the ROV. This creates continuous and unlimited rotations in place on the part of the ROV, allowing the camera to be panned and tilted. A model of the ROV is presented, and control was tested in both simulation and experiments. In addition, a dual-use system for both communication and localization of the ROV is presented. This novel dual-use system uses visible blue light (-470nm) to relay data in addition to providing a beacon with which the orientation and position in space of the ROV was estimated. This localization algorithm was implemented using an Extended Kalman Filter (EKF), and was tested in both simulations and experiments.<br>by Ian Charles Rust.<br>S.M.
8
Walker, Daniel G. (Daniel George). "Design and control of an high maneuverability remotely operated vehicle with multi-degree of freedom thrusters." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32968.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.<br>Includes bibliographical references (leaf 72).<br>This research involves the design, manufacture, and testing of a small, < lm³, < 1Okg, low cost, unmanned submersible. High maneuverability in the ROV as achieved through a high thrust-to- mass ratio in all directions. One identified solution is moving the primary thrusters in both the pitch and yaw directions. The robot is propelled by a pair of 2 DOF thrusters, and is directly controlled in heave, surge, sway, yaw, and roll. Pitch is controlled through passive buoyancy and, potentially, active manipulation of added mass and gyroscopic effects. This system is compared against a traditional fixed-thruster system in terms of cost, size, weight, and high/low speed performance. Preliminary results indicate that the actuated system can provide an improved thrust-to-mass metric at the expense of increased system complexity. This margin of improvement increases with increasing thruster size. The system has applications in high accuracy positioning areas such as ship hull inspection, recovery, and exploration.<br>by Daniel G. Walker.<br>S.B.
9
Haid, Benjamin J. (Benjamin John Jerome) 1974. "A "permanent" high-temperature superconducting magnet operated in thermal communication with a mass of solid nitrogen." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/88893.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.<br>Includes bibliographical references (p. 249-254).<br>This thesis explores a new design for a portable "permanent" superconducting magnet system. The design is an alternative to permanent low-temperature superconducting (LTS) magnet systems where the magnet is cooled by a bath of liquid helium. The new design involves a high-temperature superconducting (HTS) magnet that is cooled by a solid heat capacitor. An apparatus was constructed to demonstrate stable operation of a permanent magnet wound with Bi2223/Ag conductor while in thermal communication with a mass of solid nitrogen. The system includes a room-temperature bore and can func tion while it stands alone, detached from its cooling source, power supply, and vacuum pump. The magnet is operated in the 20-40 K temperature range. This apparatus is the first to demonstrate the operation of a superconducting magnet with a permis sible temperature variation exceeding a few degrees kelvin while a magnetic field is maintained for a useful duration. Models are developed to predict the experimental system's warming trend and magnetic field decay. The models are validated with a good agreement between simulations based on these models and experimental results. Potential performance advantages of a solid nitrogen cooled permanent HTS (SN2/HTS) magnet system over a liquid helium cooled LTS (LHe/LTS) system are explored for various applications. The SN2/HTS system design includes a second solid heat capacitor that cools a radiation shield. Recooling of the heat capacitors is performed with a detachable cryocooler. The SN2/HTS system offers both improved stability and improved portabilit over an LHe/LTS system design.<br>(cont.) Design codes are constructed to comiiie the SN2/HTS system design with a LHe/LTS design for two different applicatiohs. The first application is a general permanent superconducting magnet employing a room temperature bore. The second application is a superconducting mine countermeasures system (SCMCM) that is used to sweep passive magnetic influence mines. The codes predict the important system attributes, namely minimum volume and minimum weight, that should be expected fora given set of design requirements (i.e. field magnitude and bore size, or magnetic dipole moment) and a given set of conductor properties. Their results indicate that present HTS conductor critical current and index are not yet sufficient for producing SN2/HTS systems of a size that is comparable to that expected for a LHe/LTS system. However, the conductor properties of Bi2223/Ag have been consistently improving over the last decade, and new HTS conductors are expected to be developed in the near future. Therefore, the codes are used to determine the minimum HTS properties that are necessary for constructing a cryocooled SN2/HTS system with a size comparable to that expected for a LHe/LTS system.<br>by Benjamin J. Haid.<br>Ph.D.
10
Finbow, Maximillian. "The dynamic modelling and development of a controller for a general purpose remotely operated underwater vehicle." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20538.
Full textAbstract:
A preliminary mathematical model for the UCT SEAHOG Remotely operated underwater vehicle (ROV) is developed, including estimation of the rigid body, hydrodynamic and hydrostatic properties of the robot. A single state thruster model is developed and verified according to real life test data. A closed-loop speed controller is developed for the thruster module using a standard PI scheme and is implemented on an MSP430 microcontroller using software fixed-point algorithms. The complete ROV system is simulated in Simulink® in an open-loop configuration to gain insight into the expected motion from the vehicle. Controllers for depth and heading holding are designed using standard PID linearized control methods with gain scheduling and are then assessed within the complete system in a simulation environment. In addition, upgrades and maintenance are performed on the Power Pod, light and camera modules. Redesign, manufacture and testing of the SEAHOG junction box is performed, including a design solution to connect the tether power and fibre-optic lines at the surface and on the ROV. An extensive overhaul of the SEAHOG GUI is performed, utilising multicore processing architecture in LabVIEW and resulting in a user-orientated interface capable of controlling and monitoring all existing system data from the robot.
11
Ranganath, Jayanth Gobbalipur. "Design and development of a magnetic resonance force microscope that operates in air." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407504450.
Full text
12
Ristow, Gerald H. "A quantum mechanical investigation of the Arnol'd cat map." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27568.
Full text
13
Brandt, Adam M. "Haptic Collision Avoidance for a Remotely Operated Quadrotor UAV in Indoor Environments." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3177.pdf.
Full text
14
Automo, Si-John. "Dependency of human operator performance quality upon task complexity." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41005.
Full text
15
Keese, William. "A Remotely Operated Multi-Tracked Vehicle for Subterranean Exploration of Gopher Tortoise Burrows." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3179.
Full textAbstract:
The gopher tortoise is a land tortoise living in the southeastern United States. It is a species in decline and is listed as threatened or endangered in six different states. The gopher (as commonly referred) digs burrows that it uses for many reasons and spends most of its time underground. Problems occur when trying to estimate a population because a gopher tortoise digs more than one burrow. This thesis demonstrates an innovative way to survey and investigate a gopher tortoise burrow hole by using a multi-tracked remotely operated vehicle. The vehicle carried two cameras (fore and aft) and was equipped with a microphone and LED illumination. It has tracks on four sides to increase its propulsion ratio. Its performance was evaluated in a sand pit where parameters such as incline could be controlled, and in an actual tortoise burrow. This research was done in conjunction with the Hillsborough County Parks and Recreation Department.
16
Comeau, Raymond. "Numerical properties of the Euler operator in digital control." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60666.
Full textAbstract:
This thesis compares the numerical performance of digital control laws implemented in the Z operator, z, and the Euler operator, $ epsilon$ = ${z-1 over T}$ where T is the sampling period, and provides some useful guidelines for estimating the conservative wordlength for relatively low order controllers which are implemented using floating point arithmetic. The relative merits of these two discrete-time operators are studied analytically with regard to coefficient representation and roundoff errors, which are two major sources of numerical error. It is shown in this thesis that the $ epsilon$ operator form has superior performance in the coefficient representation to the z operator form for the sampling rates often used in practice. It is also shown that control laws implemented in the $ epsilon$ operator provide superior performance in the introduction of roundoff errors and in the propagation of these errors through subsequent sampling instants than the z operator, at least for high sampling rates. Extensive numerical simulations are also performed to compare the $ epsilon$ and z forms to obtain useful rules of thumb for estimating the wordlength required by a controller based on the sampling rate and the dynamic characteristics of the controller.
17
Buzan, Forrest T. "Control of telemanipulators with time delay : a predictive operator aid with force feedback." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14297.
Full text
18
Goss, Benjamin G. (Benjamin Graydon) 1970. "Measuring machine interference to evaluate an operator cross-training program." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80625.
Full textAbstract:
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.<br>Includes bibliographical references (p. 62).<br>by Benjamin G. Goss.<br>S.M.<br>M.B.A.
19
Salvagnin, Nicola <1995>. "IMPLEMENTATION OF THE RESULT CONTROL SYSTEM IN A GROUP OF FAMILY-OPERATED COMPANIES: THE EXAMPLE OF THE METAL-MECHANICAL SECTOR." Master's Degree Thesis, Università Ca' Foscari Venezia, 2021. http://hdl.handle.net/10579/20039.
Full textAbstract:
In recent decades, the number of family businesses has increased significantly and is becoming a growing phenomenon around the world. Recently, these companies are facing the needs and opportunities of internationalization, survival and development. The focus of this research is the management control system (MCS) required by the family business involved in the internationalization process. In the international context, the relationship between the main characteristics of a family business and the three phases of management control (planning / budget, performance evaluation and reporting) acquires a fundamental aspect for the company, its growth and survival.
To achieve these objectives, field studies were conducted to identify the most salient characteristics belonging to the two aspects under consideration, family and internationalization, and to empirically verify how these characteristics influence and conflict in the various phases of the Manage control system. The results highlighted the importance of considering the management control system a tailor-made management system for companies.
The paper divided into 4 chapters analyzes first of all the state of the art and general literature and then contextualizes itself on the small and medium-sized companies of the Italian market.
Culture, the directional pyramid and the problem of decentralization of functions are typical Italian characteristics.
The paper concludes by analyzing how the manage control system integrates into these companies, what cultural changes are necessary and what are the long-term forecasts.
20
Marinakos, Helias John. "Effects of control automation on operator attention and risk probability in high speed trains." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42675.
Full text
21
Karlsson, Ulf. "Semi-classical approximations of Quantum Mechanical problems." Doctoral thesis, KTH, Mathematics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3440.
Full text
22
Landon, Colin Donald. "Weighted particle variance reduction of Direct Simulation Monte Carlo for the Bhatnagar-Gross-Krook collision operator." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61882.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 67-69).<br>Direct Simulation Monte Carlo (DSMC)-the prevalent stochastic particle method for high-speed rarefied gas flows-simulates the Boltzmann equation using distributions of representative particles. Although very efficient in producing samples of the distribution function, the slow convergence associated with statistical sampling makes DSMC simulation of low-signal situations problematic. In this thesis, we present a control-variate-based approach to obtain a variance-reduced DSMC method that dramatically enhances statistical convergence for lowsignal problems. Here we focus on the Bhatnagar-Gross-Krook (BGK) approximation, which as we show, exhibits special stability properties. The BGK collision operator, an approximation common in a variety of fields involving particle mediated transport, drives the system towards a local equilibrium at a prescribed relaxation rate. Variance reduction is achieved by formulating desired (non-equilibrium) simulation results in terms of the difference between a non-equilibrium and a correlated equilibrium simulation. Subtracting the two simulations results in substantial variance reduction, because the two simulations are correlated. Correlation is achieved using likelihood weights which relate the relative probability of occurrence of an equilibrium particle compared to a non-equilibrium particle. The BGK collision operator lends itself naturally to the development of unbiased, stable weight evaluation rules. Our variance-reduced solutions are compared with good agreement to simple analytical solutions, and to solutions obtained using a variance-reduced BGK based particle method that does not resemble DSMC as strongly. A number of algorithmic options are explored and our final simulation method, (VR)2-BGK-DSMC, emerges as a simple and stable version of DSMC that can efficiently resolve arbitrarily low-signal flows.<br>by Colin Donald Landon.<br>S.M.
23
DeBoer, Jennifer (Jennifer J. ). "The effect of modular acoustics on a performer's perception in multi-use (symphonic and operatic) concert halls." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32865.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.<br>Includes bibliographical references (p. 34).<br>This thesis studies the varying degrees in a performer' s perception of the difference in the adjustable acoustics of a specific performance hall, namely, what is the difference between the opinions of instrumentalists and vocal musicians? Reverberation times in the Rogers Center auditorium in Andover, MA were taken onstage with the hall's acoustical curtains either hidden or exposed. Performers in the school musical and in a local symphony group were given surveys after doing two rehearsals in the hall, one in each configuration. The results from the reverberation time measurements show a clear difference between reverberation times perceived onstage. Performer surveys, however, show that neither group of performers noticed a strong contrast between different configurations of the curtains. They did, however, respond strongly when acoustics were changed that affected reflective surfaces directly surrounding them.<br>by Jennifer DeBoer.<br>S.B.
24
Bazazzadeh, Soheil. "Discontinuous mechanical problems studied with a Peridynamics-based approach." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425762.
Full textAbstract:
The classical theory of solid mechanics is rooted in the assumption of a continuous distribution of mass within a body. It employs partial differential equations (PDEs) with significant smoothness to obtain displacements and internal forces of the body. Although classical theory has been applied to wide range of engineering problems, PDEs of the classical theory cannot be applied directly on a discontinuity such as cracks. Peridynamics is considered to be an alternative and promising nonlocal theory of solid mechanics that, by replacing PDEs of classical theory with integral or integro-differential equations, attempts to unite the mathematical modelling of continuous media, cracks and particles within a single framework. Indeed, the equations of peridynamic are based on the direct interaction of material points over finite distances. Another concept, derived from the peridynamic approach to cope with engineering problems with discontinuities, is that of the peridynamic differential operator (PDDO). The PDDO uses the non-local interaction of the material points in a way similar to that of peridynamics. PDDO is capable to recast partial derivatives of a function through a nonlocal integral operator whose kernel is free of using any correction function. In this dissertation, application of peridaynamics and PDDO, to three different important engineering problems including fatigue fracture, thermo-mechanics and sloshing phenomena, is examined comprehensively.
To cope with fatigue fracture problems, an algorithm has been developed in such a way that the increment of damage due to fatigue is added to that due to the static increment of the opening displacement. A one degree of freedom cylinder model has been used to carry out an efficient comparison of the computational performance of three fatigue degradation strategies. The three laws have been implemented in a code using bond based peridynamics (BBPD) to simulate fatigue crack propagation. Both the cylinder model and the bond base peridynamics code provide the same assessment of the three fatigue degradation strategies.
To deal with thermo-mechanical problems, an effective way is proposed to use a variable grid size in a weakly coupled thermal shock peridynamic model. The proposed numerical method is equipped with stretch control criterion to transform the grid discretization adaptively in time. Hence, finer grid spacing is only applied in limited zones where it is required. This method is capable of predicting complex crack patterns in the model. By introducing fine grid discretization over the boundaries of the model the surface (softening) effect can be reduced. The accuracy and performance of the model are examined through problems such as thermo-elastic and thermal-shock induced fracture in ceramics.
Finally to investigate sloshing phenomena, the PDDO has been applied to the solution of problems of liquid sloshing in 2D and 3D tanks with potential flow theory and Lagrangian description. Moreover, liquid sloshing in rectangular tanks containing horizontal and vertical baffles are investigated to examine the robustness and accuracy of PDDO. With respect to other approaches such as meshless local Petrov-Galerkin (MLPG), volume of fluid (VOF) and and local polynomial collocation methods the examples are solved with a coarser grid of nodes. Using this new approach, one is able to obtain results with a high accuracy and low computational cost.<br>La teoria classica della meccanica dei solidi, formulata tramite equazioni differenziali alle derivate parziali (PDEs), è basata sull'assunzione di una distribuzione continua di massa all'interno di un corpo. Sebbene la teoria classica sia stata applicata ad un'ampia gamma di problemi ingegneristici, le equazioni differenziali su cui è basata non possono essere risolte agevolmente in presenza di una discontinuità come, ad es., una cricca.
La peridinamica è considerata un'alternativa ed una promettente teoria non-locale della meccanica dei solidi che, rimpiazzando le equazioni differenziali con equazioni integrali o integro-differenziali, unisce in un’unica formulazione la modellazione dei solidi continui e quella di discontinuità (ad es. cricche). Le equazioni della peridinamica sono basate sull'interazione diretta di punti materiali all’interno di una regione di influenza di dimensioni finite. Un altro concetto, derivato dall'approccio peridinamico è l'operatore differenziale peridinamico (PDDO). Questo operatore è in grado di valutare le derivate parziali di una generica funzione per mezzo di una opportuna funzione integrale non-locale.
In questa tesi viene esaminata l'applicazione della peridinamica e del PDDO a tre problemi ingegneristici: la frattura per fatica, i fenomeni termo-meccanici ed i fenomeni di sloshing.
Per simulare i problemi di frattura per fatica, è stato sviluppato un algoritmo che valuta sia l'incremento del danno per fatica, legato al numero dei cicli di carico, che l’incremento del danno statico, legato all’aumento dell’apertura della cricca. Sono state proposte tre leggi di danneggiamento per fatica le cui prestazioni computazionali sono state valutate per mezzo di un modello ad un grado di libertà. Inoltre le stesse tre leggi sono state implementate in un codice basato sulla formulazione peridinamica di tipo bond-based, per simulare la propagazione delle cricche per fatica. Sia il modello ad un grado di libertà che il codice scritto utilizzando la formulazione peridinamica individuano la stessa legge di danneggiamento per fatica (fra le 3 studiate) quale più efficiente ed accurata da un punto di vista numerico.
Per affrontare problemi di natura termo-meccanica, viene proposto un approccio alternativo che utilizza una griglia di nodi di dimensione variabile all’interno di un modello peridinamico. Il modello numerico proposto modifica in maniera adattiva la dimensione di griglia per garantire una elevata accuratezza dei risultati ed un minore sforzo computazionale: la griglia più raffinata è usata soltanto nelle aree in cui le cricche si propagano. L’approccio proposto è stato utilizzato in un primo momento per lo studio di fenomeni termo-elastici quindi per l’analisi di fenomeni di propagazione di cricche a seguito di sollecitazioni termo-meccaniche.
Infine, il PDDO è stato impiegato per investigare i fenomeni di sloshing di liquidi in serbatoi bi-dimensionali e tri-dimensionali studiati con la teoria del flusso a potenziale e la descrizione Lagrangiana. Rispetto ad altri approcci, come ad esempio il metodo locale meshless Petrov-Galarkin, il metodo dei volumi di fluido ed il metodo locale di collocazione polinomiale, l’approccio PDDO si rivela particolarmente efficace dato che fornisce risultati di accuratezza analoga (rispetto ai risultati ottenuti con gli altri approcci) impiegando un numero minore di nodi per descrivere il sistema.
25
Rintamäki, Julia. "Development of Parking Brake Component : Product Development and Mechanical Design Process." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-20812.
Full textAbstract:
This report represents the bachelor thesis examination by Julia Kastehelmi Rintamäki. The examination has been performed during spring semester 2013 at Volvo Construction Equipment in Eskilstuna. This report, Development of parking brake component, describes the product development process of the parking brake component for articulated hauler, wheel loader and grader. Volvo CE has problems with the parking brake switch that exist today on articulated hauler, wheel loader and grader. The purpose of this project is to develop one common solution for the parking brake component for articulated hauler, wheel loader and grader. The secondary purpose is to find final concept proposal for each machine. Employees at the Volvo CE were interviewed; they were contacted via e-mail, phone calls and via meetings to get the information about the machines and the information around the parking brake component. Volvo CE databases were also used for gathering information about standards and pictures. Lots of different ideas were sketched and concept proposals were created with the aid of material from marketing analysis, competitor analysis, target group analysis, requirement specification, function analysis, standards and ergonomics. Eight concept proposals were chosen to be evaluated with QFD, Pugh’s matrix and FMEA. Two concepts were most suitable and developed further to three dimensional models with the aid of Solid Works. The different aspects were taken into account when designing and dimensioning the final concepts. Two models were created with the aid of plasticine for figuring out the ergonomics and dimensions of the product. DFM, DFA, DFE, D4S were used for taking into account costs, assembly, dimensions and environmental impacts of this product. One of the concepts could replace the existing parking brake switch and suit in different cabins because of its size and design. This concept can be located on vertical or on horizontal plane. The other final concept solution functions better for the articulated hauler on account of the double function with exhausting brake system activating before parking brake system. Suggestion for next steps for the project could be to make prototypes of the two concepts and test these components in real machines. Also interviewing users for further development of the final concepts and redesign if needed.
26
Leftheriotis, George. "Development of wind turbines to operate in modified axial flows which contain swirl velocities and non-uniform distributions." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/109506/.
Full textAbstract:
In pan A of this thesis, a procedure based on lifting line theory for the design of wind turbines operating in non-uniform, non-axial but axisymmetric flows is presented. This procedure was used for the design of conventional turbines which were compared with turbine designs produced by momentum theory. The overall trends of both theories were found to be similar, although the lifting line procedure was found to produce a more conservative estimate of the turbine performance. The above mentioned design procedure was also used for the turbine blade design of the wind power systems presented in parts B and C of the thesis. Part B of the thesis deals with the development of the delta wing-turbine system: The system was scaled-up using the results of a previously developed design model, and its dimensions were compared with those of equivalent conventional turbines. It was found that the system compares well with conventional turbines up to rated power values equal to 100 kW. Its advantages were found to be the lower turbine diameter required for a given power output and the opportunity it provides for direct connection of the turbines to generators. The cost of this advantage is the relatively large delta wing required. A system prototype with power output in the order of 1 kW was designed for testing. The prototype turbine blades were designed taking into account Reynolds number effects. In order to overcome the detrimental Re effects, use of a low Re aerofoil (GOE 795), reduction of the turbine number of blades to 10, increase of the blade chord, linear blade chord distribution and variable optimum angle of attack were found to be necessary, leading to a reduction of the turbine power coefficient drop to 4.7% below that of the original high Re design. The prototype off design performance was predicted and it was found that increase of the blade chord at the hub region (for strength) and linearisation of the blade optimum twist angle (for ease of manufacture) did not affect the turbine performance significantly. The generator to be used with the prototype turbine was bench-tested. Its model parameters and power losses were identified. For matching the generator with the turbine, an appropriate load for the generator was found. The prototype long-term performance was also estimated using the turbine performance characteristics, the generator test results and the Weibull distribution of wind occurrence probability. It was found that the generator is not ideally suited for the prototype turbine and that a generator of larger ratings would be more suitable. Finally, the effects of yaw on the delta wing vortices were investigated experimentally. This was done in order to determine the feasibility of using the delta wing yaw to regulate the system power output. It was found that the above mentioned regulation technique can be used, provided that undue blade vibrations due to turbine-vortex misalignment and vortex bursting will not occur. In part C, a procedure for the design of the counter-rotating turbine blades was developed. The above mentioned lifting line procedure as well as the existing knowledge of wind turbine wakes and counter-rotating rotor aerodynamics were used for the design of the counter-rotating turbine blades and the semi-empirical modelling of the two rotors' interaction. The optimum axial distance between the two rotors was found to be equal to 1.4 times the rotors' radius. It was demonstrated that proper design of the turbine blades and appropriate axial positioning of the two rotors could increase the turbine performance by 27.4% above that of the original counter-rotating turbine design, called Trimble Mill. It was also found that a considerable increase of the generator effective rotational speed (equal to 58%) can be achieved by the counter-rotating turbine, compared to that of a conventional turbine with the same number of blades, while the two turbines' power output was found to be at the same levels.
27
Paris, Lisa. "Existence and Uniqueness of Solutions to Positive Bounded Below Operator Equations." Youngstown State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1318528385.
Full text
28
Wendland, Mitchel. "Shape from focus image processing approach based 3D model construction of manufactured part." Scholarly Commons, 2018. https://scholarlycommons.pacific.edu/uop_etds/3569.
Full textAbstract:
The purpose of this research is to develop a process and an algorithm to create a 3D model of the surface a part. This is accomplished using a single camera and a CNC machine as a movable stage. A gradient based focus measure operator written in MATLAB is used to process the images and to generate the surface model. The scopes of this research are image processing and surface model generation as well as verifying part accuracy. The algorithm is able to create a rough surface model of a photographed part, and with careful calibration in a limited number of scenarios has been used in checking part z dimensions.
29
Petkevičiūtė, Daiva. "Mechaninių virpesių sistemą aprašančių diferencialinių lygčių sprendinio reiškimas baigtine eksponenčių suma." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2007~D_20070816_142415-98558.
Full textAbstract:
Šiame darbe tiriamos naujo metodo, skirto funkcijų aproksimavimui baigtine eksponenčių suma galimybės, taikant šį metodą konkrečios diferencialinių lygčių sistemos, aprašančios mechaninius virpesius, sprendiniams. Viena iš galimų darbe pristatomos mechaninių virpesių sistemos taikymo sričių – jūros bangų arba vėjo sukeltus virpesius panaudoti kaip atsinaujinantį energijos šaltinį. Tokių mechanizmų veikimo principai prieš pradedant kurti realų veikiantį modelį analizuojami taikant matematinį modeliavimą. Sudėtingos lygčių sistemos sprendiniai, priklausomai nuo sprendimo metodo, gaunami laipsninių eilučių pavidale arba kaip taškų aibė, bet nei viena iš šių formų nėra patogi sprendinio kokybiniam tyrimui. Tačiau turint sprendinio išraišką eksponentinių funkcijų su kompleksiniais koeficientais suma, žinomi ir šį sprendinį sudarančių harmonikų dažniai – svarbi konkretaus virpesių sistemos režimo charakteristika. Atliekant skaitinius eksperimentus nustatyta, jog nusistovėjusį sistemos sprendinį galima įvertinti baigtine eksponenčių suma. Aproksimavimo paklaidos priklauso nuo žingsnio, aproksimuojamos funkcijos ir skaičiavimo paklaidos.<br>The aim of this work was to explore the possibilities of a new method, which gives an ability to approximate functions by a finite sum of exponential functions. This method was applied to the solutions of the concrete differential equations that describe the system of mechanical oscillations. One of the possible application areas of the system of oscillations presented in the paper is to use oscillations caused by the wind or water waves as a source of renewable energy. The action principles of such mechanisms are investigated using mathematical simulation before the real working model. The solutions of the sophisticated system of differential equations are obtained either in the form of power series or a set of points, depending of the solving method chosen. However, none of these forms is convenient for exploring properties of the solution. Therefore, we have a problem to approximate the solutions with linear formations of exponential functions. It is possible then to express the solutions as the linear formations of harmonics. It is demonstrated that a steady solution of the system can be expressed as a finite sum of exponential functions. Approximation errors vary depending on the distance between the points used, the function, which is being approximated, and the computation errors.
30
Gibbs, John H. "Actuated Continuously Variable Transmission for Small Vehicles." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1238819759.
Full text
31
Andersson, William, and Adrian Aune. "Development of improved determination process : Adapted for nominal setup at Volvo Car Corporation based on static, dynamic and thermal contributions." Thesis, Linköpings universitet, Maskinkonstruktion, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170864.
Full textAbstract:
A nominal setup at Volvo Cars Corporation is the placement determination for two adjacent exterior parts on the car. To place the parts in optimal positions, nominal values for gaps and flushes are determined. When a nominal setup becomes more complex, VSA (Vehicle System Architect) is summoned. These appearing situations regard the involvement of several attributes and the need for a combination of vari- ous contributions. There are static, dynamic (overslam or dynamic movement) and thermal contributions that are combined into nominal values of gap and flush dis- tances. The determination process of a nominal setup contains both calculation for each contribution, as well as the combination method which takes place at the VSA meetings. This Master Thesis project consists of the development of an improved determination process for nominal setups. The current determination process has a low level of transparency within the differ- ent group’s methods. Another issue is the insecurity of the probability estimations made when combining the contributions. Therefore, the focus of the project was to infuse a greater understanding of the contribution derivations, and greater insight into the probability of the taken risks. To achieve that, the project was divided into three parts; mapping of the determination process, individual contribution improve- ments and finally, improvements to the combination method. In contemplation of improving a process, plenty of knowledge needs to be gathered, regarding methods, simulations and possibilities. This was executed by interviewing experts within spe- cific areas at the different groups at VCC. Development of the improvements was done by interviews and various studies. It was shown that the mapping of the determination process increased the trans- parency between the groups as it increased the understanding of individual groups’ work. Contribution improvements lead to more realistic load cases used for dimen- sioning. A performed overslam clinic, where closing velocity data of a tailgate were collected, lead to a greater statistical base for which load case should be used. For dynamic movement, another method is proposed that considers relative movement instead of applied accelerations. For the thermal contribution, the approach of ge- ographically gathered temperature data was proposed. The improved combination method generates combinations with regard to three input values instead of one, from each contribution, to create different combination scenarios. The probabilities of the scenario occurrences are estimated which gave VCC a greater understanding of what risks that are taken. Furthermore, the combination method also educates the VSA meeting attendees by exhibiting the derivations and bases for each contri- bution.
32
Andersson, Ingo, and Joel Garbers. "Developing Primary Controls for Multiple CE-Machines in a Teleoperation's Environment." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49372.
Full textAbstract:
Background: An intermediate step towards fully autonomous construction equipment is “assisted tele-remote operation”. These sorts of operations imply that an operator remotely supports machines that has encountered a situation that autonomous systems onboard the construction machines (CM) cannot solve. Considering teleoperators are not required to continuously monitor the CM in an assisted tele-remote environment, multiple construction machines can be teleoperated simultaneously. For simplification, “assisted tele-remote operation” will now be referred to as “teleoperations”. Volvo Construction Equipment is currently exploring the possibility to teleoperate wheel loaders, articulated haulers, and excavators from a single platform. To do this, primary controls adapted for operating these machines are needed. The primary controls should be designed with the needs of a teleoperator in mind while taking functionality into account, which is needed when CM are both operated conventionally and in tele-remote applications. This procedure will be referred to as relevant primary controls. As the primary controls from three different CM-types are destined to be combined into one platform, the teleoperations platform will be referred to as “3-1 CM teleoperations platform”. The purpose of this thesis project was to propose a relevant solution to primary controls for a 3-1 CM teleoperations platform. To fulfil this purpose, the following two research questions (RQ) where formulated: • RQ1: What are the challenges for teleoperating construction equipment? • RQ2: What defines primary controls in a 3-1 CM teleoperations platform and how can the layout be improved? Method: Using interviews, observations, and literature as qualitative data collection methods, several insights where gained. A scenario for the CM was defined to define the situation in which the quantitative data collection method would be performed. Needs of current CM operators combined with teleoperators have been analysed and listed. Quantitative data has been collected and analysed to design the layout of the primary controls using the objective data as a basis. Result: The research questions were answered with the following results: • RQ1: Insights that resulted in several themes describing how teleoperations can be developed by looking at different challenges it can face. • RQ2: Specifications of the functions included in the new ‘primary controls’ based on CM functions from the company and from teleoperating experiences from several industries. An analysis on how often the functions for the new ‘primary controls’ were used, was carried out. The answers to the research questions were used as a basis to fulfil the purpose of this thesis project by proposing a conceptual solution for primary controls to a teleoperation’s platform for operating multiple CM. Conclusions: It was established that a 3-1 CM teleoperations platform can be developed towards certain CE-machine types. Moreover, additional analysis with experienced operators of each machine type are needed to improve and verify the most optimal layout of the primary controls and platform. Further research is still required to validate the answers to RQ1 and RQ2.
33
Randa, Daniel. "Výpočet zatížení elektrického pohonu brány." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413240.
Full textAbstract:
This thesis deals with the construction of drives for self-supporting gates. The main parts from which the drive is folded are not discussed here. In addition, the main points of load are solved which arise on the self-supporting gate and it´s contact with the guiding, carrying carts and movement elements. And here is explained what needs to be taken care of by the drive to accommodate the loads, which all aggravate the movement of the structure. in the work are also presented the load types of load calculations by which the drive parameters can be checked for suitability for the application.
34
Yu-SianChuang and 莊育賢. "Structure and Property Characterization of Mechanically Alloyed Room Temperature Operated Magnesium-Based Hydrogen Storage Alloy Powders." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/cr2v4b.
Full text
35
Huang, Ting-an, and 黃廷安. "Development and Mechanical Efficiency Test of Newly Single Side Operated Wheelchair for Hemiplegia." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43779960400943628304.
Full textAbstract:
碩士<br>國立臺南大學<br>機電系統工程研究所碩士班<br>99<br>In recent years, the increasing elderly population and declining birth rate ,since 1994,
Taiwan has formally been entered the aging society, in this aging society, elderly care and
rehabilitation is among one of the big issues, and cerebrovascular disease or commonly
known as common symptoms of stroke is being one of the most common disease.
For the poor mobility of the elderly, stroke patients due to lack of independent action of
the function, wheelchair or scooter as their main daily mobility tools. However, stroke
patients with hemiplegia in the use of general manual wheelchair, they generally remove the
pedals removed, and lower the seat height so that the healthy side of the feet can touch the
ground and control the wheelchair forward direction, but this asymmetry way of force, often
resulting in wheelchair driven eviation.
Based on this, the design of the study for patients with hemiplegia and wheelchair
product needs and shortcomings of traditional wheelchairs made improvements, operation
more easily simple line with the concept of bio-mechanics, to solve long-standing hemiplegic
patients the inconvenience of using a wheelchair.
36
Prabhakar, Sairam. "Dynamics modeling and control of variable length remotely operated vehicle tether." Thesis, 2005. http://hdl.handle.net/1828/1922.
Full textAbstract:
In this work, a computational model is developed to simulate the dynamics of variable length tether in a tethered underwater vehicle system. The system is comprised of a surface ship and winch, a slender armored cable that links the surface ship and the remotely operated vehicle (ROV), and the ROV itself. The cable is considered to be variable length to facilitate paying out and reeling in maneuvers. The motion equation for variable length tether is obtained from Newton's second law of motion for variable mass systems. Unlike many existing formulations. the model can treat the rapid deployment and retrieval of tether accurately. The Weighted Residual Finite Element technique is applied to the continuous motion equation to obtain a system of spatially discrete nonlinear second order differential equations. Time domain simulation of variable length maneuvers is used to validate the performance of the model for low and high tension cable states
The model is applied to the development of a dynamic positioning system for a submerged point on the tether, called the control node. for the Remotely Operated Platform for Ocean Sciences (ROPOS) operated by the Canadian Scientific Submersible Facility (CSSF). A decoupled controller incorporating a Dahlin Controller for positioning in the longitudinal plane and a PD Controller for depth regulation produces ship motion and winch activity to position the control node. It is shown that the use of the control system to regulate the position of the control node brings about significant reduction in the disturbance force exerted by the tether on the ROV during a station-keeping maneuver.