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1
Gu, Jie. "Development of a 6-degree-of-freedom magnetically levitated instrument with nanometer precision." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969/118.
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Calhoun, Sean M. "Six Degree-of-Freedom Modeling of an Uninhabited Aerial Vehicle." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1149543622.
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Joshi, Atul Ravindra. "Design and control of a three degree-of-freedom planar parallel robot." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1175180058.
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Ding, Jun. "Mechanism Design, Kinematics and Dynamics Analysis of a 7-Degree-Of-Freedom (DOF) Cable-Driven Humanoid Robot Arm." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1299856503.
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Yang, Yiming. "Motion synthesis for high degree-of-freedom robots in complex and changing environments." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31236.
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The use of robotics has recently seen significant growth in various domains such as unmanned ground/underwater/aerial vehicles, smart manufacturing, and humanoid robots. However, one of the most important and essential capabilities required for long term autonomy, which is the ability to operate robustly and safely in real-world environments, in contrast to industrial and laboratory setup is largely missing. Designing robots that can operate reliably and efficiently in cluttered and changing environments is non-trivial, especially for high degree-of-freedom (DoF) systems, i.e. robots with multiple actuators. On one hand, the dexterity offered by the kinematic redundancy allows the robot to perform dexterous manipulation tasks in complex environments, whereas on the other hand, such complex system also makes controlling and planning very challenging. To address such two interrelated problems, we exploit robot motion synthesis from three perspectives that feed into each other: end-pose planning, motion planning and motion adaptation. We propose several novel ideas in each of the three phases, using which we can efficiently synthesise dexterous manipulation motion for fixed-base robotic arms, mobile manipulators, as well as humanoid robots in cluttered and potentially changing environments. Collision-free inverse kinematics (IK), or so-called end-pose planning, a key prerequisite for other modules such as motion planning, is an important and yet unsolved problem in robotics. Such information is often assumed given, or manually provided in practice, which significantly limiting high-level autonomy. In our research, by using novel data pre-processing and encoding techniques, we are able to efficiently search for collision-free end-poses in challenging scenarios in the presence of uneven terrains. After having found the end-poses, the motion planning module can proceed. Although motion planning has been claimed as well studied, we find that existing algorithms are still unreliable for robust and safe operations in real-world applications, especially when the environment is cluttered and changing. We propose a novel resolution complete motion planning algorithm, namely the Hierarchical Dynamic Roadmap, that is able to generate collision-free motion trajectories for redundant robotic arms in extremely complicated environments where other methods would fail. While planning for fixed-base robotic arms is relatively less challenging, we also investigate into efficient motion planning algorithms for high DoF (30 - 40) humanoid robots, where an extra balance constraint needs to be taken into account. The result shows that our method is able to efficiently generate collision-free whole-body trajectories for different humanoid robots in complex environments, where other methods would require a much longer planning time. Both end-pose and motion planning algorithms compute solutions in static environments, and assume the environments stay static during execution. While human and most animals are incredibly good at handling environmental changes, the state-of-the-art robotics technology is far from being able to achieve such an ability. To address this issue, we propose a novel state space representation, the Distance Mesh space, in which the robot is able to remap the pre-planned motion in real-time and adapt to environmental changes during execution. By utilizing the proposed end-pose planning, motion planning and motion adaptation techniques, we obtain a robotic framework that significantly improves the level of autonomy. The proposed methods have been validated on various state-of-the-art robot platforms, such as UR5 (6-DoF fixed-base robotic arm), KUKA LWR (7-DoF fixed-base robotic arm), Baxter (14-DoF fixed-base bi-manual manipulator), Husky with Dual UR5 (15-DoF mobile bi-manual manipulator), PR2 (20-DoF mobile bi-manual manipulator), NASA Valkyrie (38-DoF humanoid) and many others, showing that our methods are truly applicable to solve high dimensional motion planning for practical problems.
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Alqasemi, Redwan M. "Maximizing manipulation capabilities of persons with disabilities using a smart 9-degree-of-freedom wheelchair-mounted robotic arm system." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002004.
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Rajesh, Edwin. "Assessment of Marine Conditions for Logistics, Operation Envelope and Weather Window for Offshore Projects." Thesis, Högskolan på Gotland, Institutionen för kultur, energi och miljö, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-217003.
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This thesis describes an assessment of offshore wind farms using a Matlab tool Marine System simulator. This tool helps to analyse the Vessel motion according to different wave heights. From this assessment one can know the correct weather window for offshore operation and other possible techniques to reduce the time delay in operation. This tool is used to simulate a supply vessel motion according to different wave heights. The chosen supply vessel is the default supply vessel in the simulator.
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Mamrak, Justin. "MARK II a biologically-inspired walking robot /." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1226694264.
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Chau, Simon Yi Ying. "Six degree of freedom joystick." Thesis, University of Canterbury. Mechanical Engineering, 2003. http://hdl.handle.net/10092/6604.
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Industrial robotics concentrates on developing automated alternatives to human function. Most of the equipment is controlled by means of joystick. Through a joystick input, a robotic arm can be guided through the trajectories to accomplish complex manipulation tasks for its user. Nevertheless, conventional joysticks are mainly two dimensional input devices such as mouse or joystick with additional buttons. Hence it is necessary to design and build a more intuitive and user-friendly joystick model. This thesis aims at designing and building a six degree of freedom (DOF) joystick. Different designs are reviewed in the beginning of the thesis, the final prototype is proposed by refining the different designs. Structural analysis of the model is performed and verified using finite element software ANSYS and PATRAN. The prototype is tested to model the movement of the wire strips when various forces are applied. Preliminary test results are obtained and explained.
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English, Chad. "Stiffness behaviour in two degree of freedom mechanisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0023/NQ52318.pdf.
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Masters, Brett P. (Brett Peter). "Multiple degree of freedom force-state component identification." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/49916.
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Anderson, Gordon A. B. (Gordon Alexander Brewster) 1977. "A six-degree of freedom flexural positioning stage." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17585.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 134-136).
A novel, low-cost positioning stage was constructed using a six-axis compliant mechanism driven by three two-axis electromagnetic actuators. The mechanism's monolithic, planar geometry is easily fabricated with low-cost manufacturing processes (such as waterjet machining). The manipulator tolerates ±1 mm actuator misalignment with less than 0.1% full-scale position error. Measurements over a 100x100x100 nm3 work volume displayed resolution better than the sensing capability, 5nm, and open-loop linearity errors less than 0.005% of the full-scale range (100 [mu]m). Measurements over a 100x100x100 [mu]m3 work volume exhibited linearity errors less than 0.20% full-scale. The mechanism's equilateral symmetry and planar geometry restricted thermal drift rates at start-up to 23nm and 4 [mu]tradians over 30 minutes and 0.1°C temperature change. The manipulator, built for $ 2000 (excluding electronics), was successfully tested in a fiber optic alignment application.
by Gordon A.B. Anderson.
S.M.
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Knight, Heather. "Expressive Motion for Low Degree-of-Freedom Robots." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/753.
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As social and collaborative robots move into everyday life, the need for algorithms enabling their acceptance becomes critical. People parse non-verbal communications intuitively, even from machines that do not look like people, thus, expressive motion is a natural and efficient way to communicate with people. This work presents a computational Expressive Motion framework allowing simple robots to modify task motions to communicate varying internal states, such as task status, social relationships, mood (e.g., emotive) and/or attitude (e.g., rushed, confident). By training robot motion features with humans in the loop, future robot designers can use this approach to parametrize how a robot generates its task motions. The hypothesis of this Thesis is that robots can modify the motion features of their task behaviors such to legibly communicate a variety of states. Typically, researchers build instances of expressive motion into individual robot behaviors (which is not scalable), or use an independent channel such as lights or facial expressions that do not interfere with the robot's task. What is unique about this work is that we use the same modality to do both task and expression: the robot's joint and whole-body motions. While this is not the only way for a robot to communicate expression, Expressive Motion is a channel available to all moving machines, which can work in tandem with additional communication modalities. Our methodological approach is to operationalize the Laban Effort System, a well-known technique from acting training, describing a four-dimensional state space of Time, Weight, Space and Flow. Thus, our Computational Laban Effort (CLE) framework can use four values, the Laban Effort Setting, to represent a robot's current state. Each value is reflected in the motion characteristics of the robot's movements. For example, a Laban Time Effort of `sudden' might have more abrupt accelerations and fast velocity, while a Laban Time Effort value of `sustained' could have slower acceleration and low velocity. In our experiments, we find that varying these four Effort values results in complex communications of robot state to the people around it, even for robots with low degrees of freedom. The technical contributions of this work include: 1. A Computational Laban Effort framework for layering Expressive Motion features onto robot task behaviors, fully specified for low degree of freedom robots. 2. Specifications for selecting, exploring and making generalizations about how to map these motion features to particular robot state communications. 3. Experimental studies of human-robot interaction to evaluate the legibility, attributions and impact of these technical components. 4. Sample evaluations of approaches to establish mappings between CLE features and state communications.
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Alshehri, Ali. "Two degree of freedom capacitive MEMS velocity sensor." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/379257/.
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This research presents the design and implementation of a novel two-degree-of-freedom (2-DoF) capacitive MEMS velocity sensor for use with structural vibration measurements. The sensor comprises two mass–spring–damper systems that are connected in series. The base principal system is used as the principal sensing element, and the other system functions as the secondary sensing element for the implementation of an internal velocity feedback loop. This loop is aimed at producing damping force on the proof mass of the principal sensing system, so that the frequency response function of the velocity sensor takes on three important properties: (1) At low frequencies below the fundamental resonance of the 2-DoF sensor, the output of the sensor becomes proportional to the velocity of the sensor’s frame. (2) Around the fundamental resonance, the sensor is characterised by a flat amplitude spectrum. (3) Finally, above the fundamental resonance, the sensor is characterised by an amplitude roll-off with only a 90° phase lag. In contrast to standard accelerometer vibration sensors, this sensor produces the desired velocity output within the bandwidth up to the first resonance frequency and generates a filtering effect with a –90° phase lag after the first resonance frequency. A piezoresistive MEMS velocity sensor presented in the literature was explored to confirm the effectiveness of the concept that drives the current 2-DoF velocity sensor. Such technique, however, is susceptible to temperature changes, presents low sensitivity and requires several fabrication steps. To avoid these drawbacks, the sensor proposed in this research was specifically designed with a capacitive transducer and an actuation technique. The sensor interface and the controller are implemented on a printed circuit board. The control loop and closed-loop response were designed by a post-process intended to measure frequency response functions (FRFs) for the displacements of the two proof masses with respect to (i) base acceleration and (ii) the electrostatic actuator applied to the principal proof mass. The comparison of the simulated and measured FRFs indicates that the MEMS sensor dynamically and closely reproduces the desired 2-DoF response. The first prototype sensor was fabricated on a silicon-on-insulator (SOI) wafer with two masks. Below 1 kHz, the measured output signal of the closed-loop sensor is proportional to the velocity of the base. Above the fundamental resonance, the output signal rolls off with a phase lag of –90°. The second prototype sensor is grounded on an innovative design and fabrication process, which enabled the direct measurement of the relative displacement between the two proof masses. The measurement was conducted using a capacitive transducer and mechanical subtraction. The second prototype was fabricated on an SOI wafer with three masks. The post-process of the measured data shows that at low frequencies (between about 300 Hz and 1 kHz), the spectrum of the sensor’s output signal is proportional to the base velocity. Around the fundamental resonance frequency, the characteristic resonance peak flattens and the phase lag decreases to –90°. These three properties are of considerable interest for the implementation of vibration control systems that use feedback loops with a collocated velocity sensor and piezoelectric patch actuator pairs.
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English, Chad (Chad Elliott) Carleton University Dissertation Engineering Mechanical and Aerospace. "Stiffness behaviour in two degree of freedom mechanisms." Ottawa, 1999.
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Gudgel, Garrett Daniel. "Three Degree-of-Freedom Parallel Actuator Telescope Mount." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1547.
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This thesis contains the design, implementation, and testing of an original, small-scaled two degree-of-freedom telescope mount and a medium-scaled three degree-of-freedom telescope mount inspired by the six degree-of-freedom Stewart-Gough platform telescope mount. The end product is intended to achieve research-standard resolution of targeted sky coverage for binary star research. The scaled prototype was carried through concept design, manufacturing, software development, and testing. The mount software development and electronic design is applicable to a full-scale mount as the drivers have been designed to be easily adapted to different actuator configurations. It is recommended that this design be implemented into a telescope in the one to two meter range for economic practicality.
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Sahler, Erica. "Analysis of a single-degree-of-freedom roll motion model: simulation, sensitivity study, and comparison to multi-degree-of-freedom models." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/7950.
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This study models roll motion response of a barge subjected to beam sea conditions as a single degree of freedom system. The measured wave, either regular or random, is input into a computer program which uses a fourth order Runge Kutta integration method to numerically predict roll motion response. The simulated results are compared to measured data to determine the best system damping parameters. Four different forms of the damping moment of the SDOF model are analyzed. In each form all coefficients are known except for the linear and nonlinear damping parameters. Each form uses a combination of relative motion Morison' damping and/or linear structural damping. Predicted results of the four forms of the damping moment are examined to determine the most suitable model. A sensitivity study on the response to various system parameters is then conducted on the selected form. Each form of the model uses a thirteenth order polynomial restoring moment. An analysis is also conducted to determine the effects of using lower order terms to represent the restoring moment. Finally, results of the SDOF model from this report are compared with a 3DOF and a 2DOF model subjected to the same wave environment to determine which model more accurately predicts roll response
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Maguire, Keir. "Multi-degree of freedom position sensor for planar motors." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54758.
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This thesis presents the development and verification of a multi-degree of freedom (DOF), non-contact position sensor for a magnetically levitated planar motor. Planar motors are intended to replace X-Y stages in various manufacturing processes resulting in higher accuracy, higher speed, and no friction. To obtain position feedback, previous planar motors have used laser interferometers, planar encoders, stereo vision, capacitive sensors, and Hall sensor arrays. For applications requiring micrometre-level precision, Hall sensor arrays are cost-effective, absolute, high bandwidth, can be integrated into the stator, and are capable of sensing multiple movers in 6-DOF over large stroke and rotation. However, previous Hall sensor arrays suffered from excessive error, low bandwidth, absolute position only within one pitch of the magnet array, modifications to the mover, lack of 6-DOF or multi-mover capability, or limited range. A 2-D Hall sensor array was developed. There are three sensors per wavelength of the magnetic field, which decouples sensor outputs for orthogonal 1-D Halbach magnet arrays. The position in 2-DOF, X and Z, is calculated for a 1-D Halbach array. The position in 6-DOF can be calculated for a planar motor mover composed of four orthogonal Halbach arrays. This sensor solution measures absolute position and is high bandwidth, multi-mover capable, and scalable with stroke. A prototype was designed, consisting of a Hall sensor array, summing amplifiers, and signal processing electronics. The prototype was tested in 2-DOF using a CNC to move a Halbach array to discrete points. Position error is approximately 200 µm peak to peak; however, the error is periodic and can be compensated. Resolution is 5 µm. Due to redundancy and averaging, improved accuracy and resolution is expected for 6-DOF sensing of the planar motor. Variation in sensor gain is a common cause of error in previous Hall sensor arrays. Previous Hall sensor arrays have only achieved good accuracy by using laser interferometers for error mapping or individual differential amplifiers to control each sensor’s gain. A sensor sorting setup was designed, built, and used to sort more than 12,000 sensors based on gain. The sorted sensors can be used for a sensor array with micrometre-level accuracy.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Carretero, G. Juan Antonio. "Analysis of a three degree-of-freedom parallel mechanism." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ36612.pdf.
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Opong, George Kofi. "Design of a six-degree-of-freedom mechanical arm." Ohio : Ohio University, 1985. http://www.ohiolink.edu/etd/view.cgi?ohiou1184071995.
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Wang, He. "Control of objects with a high degree of freedom." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7950.
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In this thesis, I present novel strategies for controlling objects with high degrees of freedom for the purpose of robotic control and computer animation, including articulated objects such as human bodies or robots and deformable objects such as ropes and cloth. Such control is required for common daily movements such as folding arms, tying ropes, wrapping objects and putting on clothes. Although there is demand in computer graphics and animation for generating such scenes, little work has targeted these problems. The difficulty of solving such problems are due to the following two factors: (1) The complexity of the planning algorithms: The computational costs of the methods that are currently available increase exponentially with respect to the degrees of freedom of the objects and therefore they cannot be applied for full human body structures, ropes and clothes . (2) Lack of abstract descriptors for complex tasks. Models for quantitatively describing the progress of tasks such as wrapping and knotting are absent for animation generation. In this work, we employ the concept of a task-centric manifold to quantitatively describe complex tasks, and incorporate a bi-mapping scheme to bridge this manifold and the configuration space of the controlled objects, called an object-centric manifold. The control problem is solved by first projecting the controlled object onto the task-centric manifold, then getting the next ideal state of the scenario by local planning, and finally projecting the state back to the object-centric manifold to get the desirable state of the controlled object. Using this scheme, complex movements that previously required global path planning can be synthesised by local path planning. Under this framework, we show the applications in various fields. An interpolation algorithm for arbitrary postures of human character is first proposed. Second, a control scheme is suggested in generating Furoshiki wraps with different styles. Finally, new models and planning methods are given for quantitatively control for wrapping/ unwrapping and dressing/undressing problems.
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Ward, Derek Kempton. "Design of a two degree of freedom robotic finger." Thesis, University of Canterbury. Mechanical Engineering, 1996. http://hdl.handle.net/10092/6480.
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The design of mechanical hands has been investigated at many universities. Most of the hands produced by their research have large actuator packs which are usually heavy and located remotely from the hand. They are also complex to control
A number of robotic hand designs are reviewed and their shortcomings are discussed briefly. A feasibility study in 1993 at the University of Canterbury on a mechanically linked finger was used as the starting point for the design of a new finger - the Canterbury finger. Several combinations of electric drive motors, gearboxes, lead screws and mechanical linkages were examined before the final configuration was selected. The result is a human sized finger and hand capable of exerting a reasonable force at the finger tip, and able to curl through 180° in two distinct motions. While the dexterity typical of tendon operated fingers is retained, the new design avoids the elasticity and friction problems of tendon operated hands.
A single mechanically linked two degree-of-freedom (DOF) finger was designed, built and tested. The design and performance criteria were met, and the working finger provided insight into areas for improvement and future development. This thesis includes manufacturing drawings, test results, and basic control software for the Canterbury finger.
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Joo, Han Kyul. "Single-degree-of-freedom energy harvesters by stochastic excitation." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92138.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 97-100).
In this thesis, the performance criteria for the objective comparison of different classes of single-degree-of-freedom oscillators under stochastic excitation are developed. For each family of oscillators, these objective criteria take into account the maximum possible energy harvested for a given response level, which is a quantity that is directly connected to the size of the harvesting configuration. We prove that the derived criteria are invariant with respect to magnitude or temporal rescaling of the input spectrum and they depend only on the relative distribution of energy across different harmonics of the excitation. We then compare three different classes of linear and nonlinear oscillators and using stochastic analysis tools we illustrate that in all cases of excitation spectra (monochromatic, broadband, white-noise) the optimal performance of all designs cannot exceed the performance of the linear design. Subsequently, we study the robustness of this optimal performance to small perturbations of the input spectrum and illustrate the advantages of nonlinear designs relative to linear ones.
by Han Kyul Joo.
S.M.
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Barnes, Lesley M. (Lesley Michelle). "The inelastic response of multiple-degree-of-freedom systems." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42602.
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Maldonado, Gustavo Omar. "Stochastic response of single degree of freedom hysteretic oscillators." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45804.
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During strong ground shaking structures often become inelastic and respond hysteretically. Therefore, in this study some hysteretic models commonly used in seismic structural analysis are studied. In particular the characteristics of a popular endochronic model proposed by Bouc and Wen are examined in detail. In addition, analytical expressions have also been developed for most commonly used bilinear model as well as another model, herein called as the hyperbolic model.Master of Science
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Kruep, John M. "Six degree of freedom optimal trajectories for satellite rendezvous." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-02132009-171146/.
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Zou, Maorong. "Geometry of two degree of freedom integrable Hamiltonian systems." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185996.
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In this work, several problems in the field of Hamiltonian dynamics are studied. Chapter 1 is a short review of some basic results in the theory of Hamiltonian dynamics. In chapter 2, we study the problem of computing the geometric monodromy of the torus bundle defined by integrable Hamiltonian systems. We show that for two degree of freedom systems near an isolated critical value of the energy momentum map, the monodromy group can be determined solely from the local data of the energy momentum map at the singularity. Along the way, we develop a simple method for computing the monodromy group which covers all the known examples that exhibit nontrivial monodromy. In chapter 3, we consider the topological aspects of the Kirchhoff case of the motion of a symmetric rigid body in an infinite ideal fluid. The bifurcation diagrams are constructed and the topology of all the invariant sets are determined. We show that this system has monodromy. We show also that this system undergoes a Hamiltonian Hopf bifurcation as the couple resultant passes through a certain value when the steady rotation of the rigid body about its symmetry axis changes stability. Chapter 4 is devoted to checking Kolmogorov's condition for the square potential pendulum. We prove, by essentially elementary methods, that Kolmogorov's condition is satisfied for all of the regular values of the energy momentum map. In chapter 5, we use Ziglin's theorem to prove rigorously that some of the generalized two degree of freedom Toda lattices are non-integrable.
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Gatti, Rathishchandra Ramachandra. "Spatially-varying multi-degree-of-freedom electromagnetic energy harvesting." Thesis, Curtin University, 2013. http://hdl.handle.net/20.500.11937/161.
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This work presents the theoretical modelling of a novel spatially varying multi-degree of freedom electromagnetic vibration energy harvester(EMVEH) that integrates two novel strategies of energy harvesting - the spatial variation of the magnetic field and the design of multi-degree of freedom energy harvesters thus making a very versatile electromagnetic energy harvester model. The EMVEH models were theoretically formulated using analytical and numerical simulation and then followed by experimental validation.
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Tibhirt, Amel. "Mitigation of Cross-link Interference for MIMO TDD Dynamic Systems in 5G+ Networks." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS017.pdf.
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Le TDD dynamique joue un rôle crucial dans les réseaux 5G, adaptant les ressources aux besoins variés. Il améliore l'efficacité spectrale en allouant dynamiquement des créneaux horaires pour les transmissions montantes et descendantes en fonction de la demande de trafic et des conditions de canal. Cette allocation dynamique de fréquence assure une utilisation efficace du spectre et prend en charge une connectivité massive, une latence faible et les exigences de la qualité de service. Son rôle dans l'agrégation de porteuses maximise les débits de données et la capacité du réseau, soulignant son importance dans les technologies de communication sans fil avancées.Cependant, le TDD dynamique est confronté à un défi majeur : l'Interférence des liens croisés. Ce type d'interférence se produit lorsque les transmissions montantes et descendantes partagent les mêmes bandes de fréquences, provoquant des interférences.Cette interférence comprend l'interférence de Station de Base à Station de Base (BS-to-BS) ou du lien descendant au lien montant (DL-to-UL) ainsi que l'interférence d'Équipement Utilisateur à Équipement Utilisateur (UE-to-UE) ou du lien montant vers le lien descendant (UL- to-DL). Dans l'interférence DL-to-UL, les transmissions descendantes débordent dans les bandes des transmissions montantes, dégradant la communication montante. À l'inverse, l'interférence UL-to-DL se produit lorsque les transmissions montantes interfèrent avec la réception des transmissions descendantes.Gérer efficacement ces interférences est crucial pour la performance et la fiabilité d'un système TDD dynamique.Ce mémoire vise à libérer tout le potentiel du TDD dynamique en surmontant les défis posés par les interférences des liens croisés grâce à une analyse rigoureuse et des méthodologies innovantes. La recherche ne se contente pas de faire progresser la technologie TDD dynamique, elle pionnière des solutions applicables à divers contextes de communication, stimulant des stratégies innovantes d'alignement d'interférence dans des scénarios variés.Le mémoire se divise en plusieurs parties. La première pose les bases avec la définition du problème et les concepts théoriques essentiels. La deuxième partie examine les conditions de faisabilité de l'alignement des interférences. Ces conditions sont exprimées en fonction de la dimension du problème et établissent le degré de liberté (DoF) atteignable, représentant le nombre de flux de données possibles. Elle explore l'alignement d'interférence dans des scénarios centralisés, en considérant à la fois les canaux MIMO en rang complet et réduit, et aborde des complexités du monde réel. De plus, elle étend l'exploration à un scénario distribué, offrant une compréhension réaliste des complexités de la communication. La troisième partie se concentre sur les techniques d'optimisation, en particulier le beamforming. Elle introduit le Zero Forcing (ZF) beamforming pour les utilisateurs, alignant l'interférence dans les systèmes TDD dynamique. Elle met l'accent sur l'impact de l'interférence des liens croisés entre utilisateurs et présente les améliorations apportées par les algorithmes WMMSE. De plus, elle explore l'optimisation de l'allocation de puissance en utilisant l'algorithme Water-Filling, évaluant la performance du Zero Forcing Beamforming et de l'algorithme WMMSE en fonction de cette approche d'optimisation de puissanceDynamic Time Division Duplexing (DynTDD) is pivotal in 5th generation (5G) networks, adapting resources to diverse needs. It enhances Spectral Efficiency (SE) by dynamically allocating time slots for Uplink (UL) and Downlink (DL) transmissions based on traffic demand and channel conditions. This dynamic frequency allocation ensures efficient spectrum use and supports massive connectivity, low latency, and Quality-of-Service (QoS) requirements. Its role in carrier aggregation maximizes data rates and capacity, highlighting its importance in advanced wireless communication technologies.However, DynTDD faces a significant challenge: cross-link interference (CLI). CLI occurs when UL and DL transmissions share the same frequency bands, leading to interference.CLI comprises base station to base station (BS-to-BS) or downlink to uplink (DL-to-UL) interference and user equipment to user equipment (UE-to-UE) or uplink to downlink (UL-to-DL) interference. In DL-to-UL interference, DL transmissions spill into UL bands, degrading UL communication. Conversely, UL-to-DL interference occurs when UL transmissions interfere with DL reception.Effectively managing CLI is crucial for DynTDD's performance and reliability.This thesis aims to unleash the full potential of DynTDD by overcoming CLI challenges through rigorous analysis and innovative methodologies. The research not only advances DynTDD technology but also pioneers solutions applicable to various communication contexts, driving innovative interference alignment strategies across diverse scenarios.The study in this thesis is divided into multiple segments. The first part establishes the foundation with the problem definition and essential theoretical concepts. The second part delves into the conditions determining the feasibility of interference alignment. These conditions are expressed in terms of the problem dimension and establish the achievable Degree of Freedom (DoF), representing the number of data streams. It explores interference alignment in centralized scenarios, considering both full-rank and reduced-rank Multiple-Input Multiple-Output (MIMO) Interference Broadcast Multiple Access Channel-Interference Channel (IBMAC-IC), addressing real-world complexities. Additionally, it extends the exploration to a distributed scenario, providing a realistic understanding of communication complexities. The third part focuses on optimization techniques, specifically beamforming. It introduces Zero Forcing (ZF) beamforming for both DL and UL User Equipment (UE)s to align CLI in DynTDD systems. It emphasizes the impact of UE-to-UE interference and presents improvements brought by the Weighted Minimum Mean Square Error (WMMSE) algorithms. Furthermore, it explores power allocation optimization using the water-filling algorithm
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Yokoyama, Takayuki. "Verification and Expansion of Single-Degree-of-Freedom Transformation Factors for Beams Using a Multi-Degree-of-Freedom Non-Linear Numerical Analysis Method." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/638.
Full textAbstract:
The single-degree-of-freedom (SDOF) transformation factors as tabulated in John Biggs’ textbook (Biggs 1964) are accepted as the equivalent factors for simplifying and analyzing a component's response to blast. The study validates the stiffness and mass transformation factors through multi-degree-of-freedom (MDOF) numerical methods. After validating the transformation factors, the MDOF numerical method is used to create new stiffness and mass transformation factors for loading cases not already included in Biggs’ textbook.
The validated factors, as well as the newly developed factors are used in SDOF analyses. The deflections from the SDOF responses accurately predict the MDOF responses as long as the component behaves elastically; however, the deflections diverge when inelastic behavior is involved. The diverged deflections indicate that the SDOF inelastic response analysis method can be improved.
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Brown, Brett C. "Design of a single-degree-of-freedom biped walking mechanism." Connect to resource, 2006. http://hdl.handle.net/1811/6435.
Full textAbstract:
Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formatted into pages: contains vi, 55 p.; also includes graphics. Includes bibliographical references (p. 43). Available online via Ohio State University's Knowledge Bank.
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Gullayanon, Rutchanee. "Motion Control of 3 Degree-Of-Freedom Direct-Drive Robot." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6969.
Full textAbstract:
Modern motion controllers of robot manipulators require knowledge of the system's dynamics in order to intelligently predict the torque command. The main objective for this thesis is to apply various motion controllers on a parallel direct drive robot in simulations and verify if one can take advantage of the model knowledge to improve performance of controllers. The controllers used in this thesis varied from simple PD control with position and velocity reference only applied independently at each joint to more advanced PD control with full dynamic feedforward term and computed torque control, which incorporate full dynamic knowledge of the manipulator. In the first part, a thorough study of deriving dynamic equation using Lagrange formulation has been presented as well as the actual derivation of dynamic equations for MINGUS2000. Next, in order to prepare proper sets of inputs for the simulations, detailed discussions of end effector trajectory path planning and inverse kinematics determination have been presented. Finally, background theories of various controllers used in this thesis have been presented and their simulation results on the closed-chain direct drive robot have been compared for verification purposes.
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Gurbuz, Sarper. "Design And Construction Of A Six Degree Of Freedom Platform." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607806/index.pdf.
Full textAbstract:
ABSTRACT
DESIGN AND CONSTRUCTION OF A
SIX DEGREE OF PLATFORM
Gürbü
z, Sarper M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. Tuna BALKAN Co-Supervisor: Prof. Dr. M. A. Sahir ARIKAN November 2006, 83 pages In this thesis a six degree of freedom (DOF) parallel manipulator is designed, developed and simulated virtually. The platform, which is specified and focused on in this thesis, is the specific solution for the generating the required data to simulate a land, airborne or sea vehicle&
#8217
s motion trajectory in the laboratory environment. After explaining the need for such platforms for the military industry, the existing devices will be presented and discussed. Then the design period will be explained while pointing out the key performance criteria. The gathered performance values of the first design iteration will be presented and the modifications done in order to get to the expected performance will be given. Finally an investigation, in order to find the maximum payload that the platform can handle, is performed and presented. It is too hard to get to the desired performance values in mechanical design and manufacturing without using the CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing) programs. In this thesis ProEngineer Wildfire®
is used for solid modeling the components, the sub-assemblies and the final assembly, ANSYS Workbench®
is used for investigating the modal behavior of the components, ADAMS®
2003 is used for the dynamic simulation of the mechanism, ADAMS/Flex®
, ADAMS/AutoFlex®
and ADAMS/Durability®
are used to analyze the results when flexibility is embedded into the system. At the end of the thesis in Appendix section five technical drawings with the nominal dimensions are given in order to clarify the construction period. By the regulations that must be obeyed in ASELSAN only the nominal dimensions are given in the technical drawings. All the dimensional and geometrical tolerances are given in the approved technical drawings that are proprietary of ASELSAN. Keywords: 6-Axis Motion Platform, Application of CAD and analysis programs, Electromechanical Design, Stewart Platform
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Dyck, Mark. "Magnetically levitated six degree of freedom micro-machining rotary table." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51753.
Full textAbstract:
This thesis presents a six degree of freedom magnetically levitated rotary table
that has one unlimited rotation axis. The actuation force is achieved by the Lorentz
force. The underside of the actuator has an axial Halbach array mounted circumferentially near the outside edge. Force is produced in the stator coils which are made using a printed circuit board. The purpose of this table is for a micro-machining rotary table application. Benefits of this table are its compact, lightweight, no friction and high precision characteristics.
Control of the table in six degrees of freedom is achieved by dividing the stator into quarters. Each quarter is driven by a linear three phase current amplifier.
For each quarter two forces can be generated, one in the levitation direction and
one in the tangential direction. This creates eight independently controlled forces
allowing for full six degrees of freedom control. Position feedback for the stage
is achieved by using four capacitive displacement measurement probes and four
optical encoders around a circular optical grating. Performance of the table has
been tested and the results show that the closed loop bandwidth for all axes is between ∼ 250Hz and ∼ 550Hz. Regulation error in the X,Y and Z axes is less than
55nm while the A,B and C axes are better than 1.2µrad (0.248 arc seconds). Force
capacity has been tested up-to 70N with a theoretical limit of 140N.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Tremaine, Daren Paul. "A six degree of freedom goniometer for the rabbit knee." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq20887.pdf.
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Nyzen, Robert J. "Analysis and control of an eight degree-of-freedom manipulator." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175796367.
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Li, Shi. "Dynamic optimization of an N degree-of-freedom robot system." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178218770.
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Nayfeh, Tariq Ali. "Dynamics of three-degree-of-freedom systems with quadratic nonlinearities." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10222009-125017/.
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Fitzgerald, Jessica L. "Characterization parameters for a three degree of freedom mobile robot." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/38929.
Full textAbstract:
Approved for public release; distribution is unlimited.Control and Navigation logic was developed for a 3-Degree of Freedom Surf-Zone Robot to assist in the identification and characterization of platform parameters for use in the Shuey Dynamic Model. These parameters included, primarily platform rotational inertia and wheel slip. Data was collected in various track scenarios including benign flat terrain and more complicated beach runs. Track lengths spanned short straight paths of no more than 10 meters to full-run point-to-point autonomous navigation paths of up to 80 meters. The longer runs included turns of up to 180 degrees and terrain inclines of 2 degree or less. As expected the Shuey model proved reliable for short runs of no more than 10 meters. For long length runs in the beach environment the Dynamic Model diverged quickly. This is attributed to, primarily, wheel slip conditions and the fact that the Shuey Model is open loop. Motor current was monitored under load conditions to identify wheel slip and simple algorithms were implemented to account for this with little success. However, closed loop heading input resulted in significant improvement to the model.
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Suleiman, Baha M. "Identification of Finite-Degree-of-Freedom Models for Ship Motions." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/30069.
Full textAbstract:
Accurate ship-motion prediction is important because it is directly related to the design, control, and economic operation of ships. Many methods are available for studying and predicting ship motions, including time-domain, strip-theory, and system-identification-based predictions. Time-domain and strip-theory predictions suffer from several physical and computational limitations. In this work, we use system-identification techniques to predict ship motions. We establish an identification methodology that can handle general finite-degree-of-freedom (FDOF) models of ship motions.
To establish this methodology, we derive the correct form of the equations of motion. This form contains all relevant linear and nonlinear terms.
Moreover, it explicitly specifies the dependence of the linear and nonlinear parameters on the forward speed. The energy-formulation approach is utilized to obtain full nonlinear ship-motion equations. The advantages of using this formulation are that self-sustained motions are not allowed and the dependence of the parameters on the forward speed is derived explicitly.
The data required for the identification techniques are generated using the Large Amplitude Motions Program (LAMP) developed by the Science Applications International Corporation (SAIC). The ship studied in this work is a Series 60 ship, which is a military cargo ship. LAMP data for different sea states and forward speeds are used to identify and predict the ship motions.
For linear parametric identification, we use the Eigensystem Realization Algorithm (ERA) to determine the coefficients in the linearly coupled equations and the effects of the forward speed on these coefficients.
For linear nonparametric identification, we present a new analysis technique, namely, the circular-hyperbolic decomposition (CHD), which avoids the leakage effects associated with the discrete Fourier transform (DFT). The CHD is then utilized to determine transfer functions and response amplitude operators (RAOs).
For nonlinear parametric identification, we present a methodology that is a combination of perturbation techniques and higher-order spectral moments.
We apply this methodology to identify the nonlinear parameters that cause parametric roll resonance. The level of accuracy of the models and the parameter estimates are determined by validations of the predicted ship motions with the LAMP data.Ph. D.
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Cordle, William H. "Numerical inverse kinematics for a six-degree-of-freedom manipulator." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12052009-020222/.
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Patterson, Timothy Fredrick. "Reduction of compliance in space-based redundant degree-of-freedom manipulators." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/18396.
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Sergio, Lauren E. (Lauren Elisabeth). "Coordination of multiple muscles in two degree of freedom elbow movements." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28916.
Full textAbstract:
The present study quantifies electromyographic variables in one and two degree of freedom elbow movements involving flexion/extension and pronation/supination, in order to understand the associated central commands. Agonist burst magnitude varied with motion in a second degree of freedom for some muscles but not for others. In movements for which a biarticular muscle acted as agonist in two degrees of freedom, agonist burst magnitudes were approximately the sum of the magnitudes in the component movements. Agonist burst magnitude varied with motion in a second degree of freedom for some, but not all, monoarticular muscles. When biarticular muscles acted as agonist in one degree of freedom and antagonist in the other, the muscle often displayed both components simultaneously. The additivity of EMG burst magnitudes in two degree of freedom movements and the presence of both agonist and antagonist bursts in a muscle suggest that central commands associated with motion in individual degrees of freedom are superimposed in producing two degree of freedom movements.
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Chong, Yon-Ho. "Non-linear vibration analysis techniques for multi-degree-of-freedom systems." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313961.
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Sparks, Russell. "A novel six degree of freedom dynamic wind tunnel test facility." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492066.
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LOYOLA, NILTON ALEJANDRO CUELLAR. "FIVE DEGREE-OF-FREEDOM HAPTIC INTERFACE FOR TELEOPERATION OF ROBOTIC MANIPULATORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21171@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
O sucesso de diversas tarefas de teleoperacao depende muito da habilidade do operador e de sua capacidade de perceber o ambiente de trabalho. A realimentacao visual em muitos casos nao e suficiente, por exemplo quando a qualidade da imagem do ambiente de trabalho e baixa, quando ocorrem oclusoes na visualizacao, ou quando a tarefa envolve forcas de contato associadas a folgas pequenas visualmente imperceptıveis. Para compensar essas deficiencias, os dispositivos hapticos surgem como uma alternativa a realimentacao visual, ao interagir com o usuario atraves do tato, produzindo uma sensacao de forca. Esta dissertacao apresenta o desenvolvimento e modelagem de um sistema de interface haptica de cinco graus de liberdade para a teleoperacao de robos manipuladores, com foco naqueles que realizam trabalhos em ambientes perigosos ou hostis ao ser humano. A interface e desenvolvida a partir do acoplamento de dois dispositivos hapticos comerciais Novint Falcon, de tres graus de liberdade cada. O sistema resultante do acoplamento e modelado como um manipulador paralelo, capaz de fornecer ao operador, realimentacao de forca 3D (em tres direcoes) e realimentacao de torque em duas direcoes. Para demonstrar a eficiencia do sistema haptico desenvolvido, um ambiente virtual e implementado com o auxılio de tecnicas de computacao grafica e bibliotecas como OpenGL, ODE e Chai3D. Os modelos cinematico e dinamico de um manipulador serial Schilling Titan IV, de seis graus de liberdade, sao implementados no ambiente virtual, incluindo sua interacao com objetos (virtuais) do ambiente de teleoperacao. Controladores nao lineares sao implementados no manipulador serial virtual, incluindo controle de torque computado, robusto, e por modos deslizantes.
The success of many teleoperation tasks depends heavily on the skills of the operator and his ability to perceive the work environment. Visual feedback, in many cases, is not sufficient e.g. when the image quality of the work environment is low, occlusions occur in the display, or when the task involves contact forces associated with visually unnoticeable small clearances. To compensate for these shortcomings, haptic devices emerge as an alternative to visual feedback, in which touch interaction with the user produces force-feedback. This thesis presents the development and modeling of a haptic interface system of five degrees of freedom for the teleoperation of robot manipulators, focusing on those that work in hazardous or hostile environments for humans. The interface is developed from the coupling of two commercial haptic devices Novint Falcon, with three degrees of freedom each. The system resulting from the coupled devices is modeled as a parallel manipulator capable of providing the operator with 3D force feedback (in three dimensions) and torque feedback in two directions. To demonstrate the effectiveness of the developed haptic system, a virtual environment is implemented with the aid of computer graphics techniques and libraries such as OpenGL, ODE and Chai3D. The kinematic and dynamic models of a serial manipulator Schilling Titan IV, with six degrees of freedom, are implemented in the virtual environment, including its interaction with virtual objects for the evaluation of typical teleoperation tasks. Nonlinear controllers are implemented in the virtual serial manipulator, including computed torque and sliding mode control.
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Olson, Sean Michael. "Nonlinear compensation of a single degree of freedom magnetic suspension system." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12067.
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Penn, James Douglass. "A Multiple Degree of Freedom Actuator using a single vibrating transducer." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74908.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 127-129).
Multiple degree of freedom actuation typically requires one actuator for each degree of freedom, where each actuator requires its own heavy and expensive transducer to transform an electrical input signal into a useful mechanical output. Mechanisms can be used to split the output of a single motor, but the resulting systems are often complex, large, heavy, and noisy. Some also lack true independence of outputs. This thesis develops and demonstrates a novel system for multiple degree of freedom actuation using a single transducer to achieve independent, bi-directional control of multiple degrees of freedom. The resulting system is mechanically simple, compact, lightweight, easy to control, and potentially inexpensive. The Multiple Degree of freedom Actuator (MDA) comprises i) a single vibrating transducer and ii) a parallel network of resonators. Each resonator is tuned to its own unique resonant frequency and drives its own degree of freedom. First, it is shown that the MDA can actuate independently multiple degrees of freedom with a single transducer by selectively exciting the resonant frequencies of one or more resonators, which then drive their respective degrees of freedom. Both numerical simulation and physical prototypes are used to verify the results. Second, a simple, compact resonator/rectifier mechanism is developed and fabricated using flexures that convert oscillating motion of a resonator to useful, continuous, bi-directional rotation of an output rotor without crosstalk between outputs. Third, the theoretical efficiency of the MDA, driven by an electromagnetic transducer, is derived. An efficient, low-moving-mass moving magnet transducer is developed and shown to greatly improve theoretical system efficiency. Finally, a hypocycloid speed reducer mechanism is developed and fabricated to achieve a very high reduction ratio in a compact package with greater simplicity and improved performance.
by James Douglass Penn.
Ph.D.
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Massie, Thomas Harold. "Design of a three degree of freedom force-reflecting haptic interface." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/11281.
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Breton, Alexander (Alexander G. ). "Simulations of a three degree of freedom brachiating Y-bot robot." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105714.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages [23]-[24]).
Brachiation is a means of locomotion for lightweight apes like gibbons. It involves the animal swinging its arms to gain moment and swing forward. A large amount of research has been done studying a simplified two-link two DOF robot, named "acrobot" by Mark Spong. While the problems of this robot have been studied extensively, it's functionality is quite limited. This paper studies a three-link three DOF brachiating robot, dubbed "Y-bot". The goal of adding the extra link is to add functionality. Simulations of a model were run in Matlab taking advantage of Russ Tedrake's toolbox Drake, which was designed to solve optimization problems of underactuated systems. The main method used in the trajectory optimization was direct collocation. The task of the robot in the simulations was to swing from a one "branch" point to another. The trajectories of two Y-bot models swinging from rest were optimized. Furthermore, the gait of one of the models was examined, and a beneficial state for the second swing of a gait was suggested. A method to optimizing the gait of a model was proposed. A linear relationship between the total trajectory time and the scale of the model was defined. The paper suggests a physical model of the Y-bot could be constructed using Saito's two DOF brachiating robot as a benchmark. The problems of gait optimization and payload transportation were mentioned as future work to be done.
by Alexander Breton.
S.B.