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Automatic Positioning and Design of a Variable Baseline Stereo BoomFanto, Peter Louis 17 August 2012 (has links)
Conventional stereo vision systems rely on two spatially fixed cameras to gather depth information about a scene. The cameras typically have a fixed distance between them, known as the baseline. As the baseline increases, the estimated 3D information becomes more accurate, which makes it advantageous to have as large a baseline as possible. However, large baselines have problems whenever objects approach the cameras. The objects begin to leave the field of view of the cameras, making it impossible to determine where they are located in 3D space. This becomes especially important if an object of interest must be actuated upon and is approached by a vehicle.
In an attempt to overcome this limitation, this thesis introduces a variable baseline stereo system that can adjust its baseline automatically based on the location of an object of interest. This allows accurate depth information to be gathered when an object is both near and far. The system was designed to operate under, and automatically move to a large range of different baselines.
This thesis presents the mechanical design of the stereo boom. This is followed by a derivation of a control scheme that adjusts the baseline based on an estimate object location, which is gathered from stereo vision. This algorithm ensures that a certain incident angle on an object of interest is never surpassed. This maximum angle is determined by where a stereo correspondence algorithm, Semi-Global Block Matching, fails to create full reconstructions. / Master of Science
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[en] DIGITAL CONTROL OF A PNEUMATIC POSITIONING SYSTEM FOR BIOMAGNET MEASUREMENTS / [pt] CONTROLE DIGITAL DE UM SISTEMA PNEUMÁTICO DE POSICIONAMENTO PARA MEDIDAS BIOMAGNÉTICASGUILHERME SESTO KUHNER 11 December 2006 (has links)
[pt] Este trabalho apresenta uma solução para o problema de
posicionamento automático preciso de um corpo em um plano
horizontal, atendendo à restrição de não gerar campo
magnético significativo junto ao objeto a ser posicionado.
A motivação do trabalho reside na necessidade, por parte
do Laboratório de Supercondutividade Aplicada e Magnetismo
(LSAM) do Departamento de Física, de um posicionador para
experimentação em magnetocardiografia.
Inicialmente são discutidas as tecnologias de
automação aplicáveis ao problema, justificando-se a opção
por um sistema pneumático de atuação. O sistema posicionar
montado é então descrito em profundidade, abordando-se os
aspectos relacionados à geometria do problema em questão,
materiais, montagens mecânicas e o sistema de controle
digital.
A seguir é apresentada uma abordagem matemática
para o problema de controle de posição em malha fechada,
visando à definição de uma lei de controle aplicável ao
caso em estudo. Alguns resultados analíticos são obtidos
para controle de sistema caracterizados por atrito
Coulombiano, ao mesmo tempo em que se desenvolve um modelo
para simulação numérica da dinâmica de movimento do
posicionador. Com base nestas duas ferramentas, é
apresentada uma discussão sobre a aplicabilidade dos
controladores da família PID ao caso específico
considerado. Por fim, resultados reais obtidos com a lei
de controle proposta são comparadores aos resultados
simulados, mostrando-se a validade e a utilidade do modelo
teórico. / [en] This thesis presents a solution or the problem of
automatic precise positioning of na object in the
horizontal plane, not generating any significative
magnetic field in the region close to the object to be
positioned. The study presented was developed as part of
an effort to fulfill a necessity for a positioning system
for magnetocardiography experimentation in the Magnetism
and Applied Supercondutivity Laboratory of the Departament
of Physics of this University.
A discussion over applicable automation option is
presents, along with a justification for a choice of a
pneumatic actuating system. The whole precise positioning
assembly is described in detail, including subjects such
as movement geometry, material, mechanical structures and
the digital control system.
A mathematical study of the closed of the closed
loop position control problem is then developed, aiming to
define a control algorithm applicable to the problem.
Algebraic analysis is used to describe the influence of
Coulomb friction over the equations of motion of a
proportional position control system, while a model for
simulations experiments of the assembly´s positioning
dynamics is developed. These tools are used as the basis
for a discussion over the applicability of the PID
controlers in the case in study. Moreover, the behavior of
the proposed algorithm is recorded and compared to the
results of the simulations, showing the correctness and
the utility of the theoretical analysis.
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Automatic Image Based Positioning SystemAeddula, Omsri Kumar January 2017 (has links)
Position of the vehicle is essential to navigate the vehicle along a desired path without any human interference. Global Positioning System (GPS) loses significant power due to signal attenuation caused by construction buildings. A good positioning system should have both good positioning accuracy and reliability. The purpose of this thesis is to implement a new positioning system using camera and examine the accuracy of the estimated vehicle position on a real-time scenario. The major focus of the thesis is to develop two algorithms for estimation of the position of the vehicle using a static camera and to evaluate the performance of the proposed algorithms. The proposed positioning system is based on two different processes. First process uses center of mass to estimate the position, while the second one utilizes gradient information to estimate the position of the vehicle. Two versions of the positioning systems are implemented. One version uses center of mass concept and background subtraction to estimate the position of the vehicle and the other version calculates gradients to estimate the position of the vehicle. Both algorithms are sensitive to point of view of the image i.e height of the camera. On comparing both algorithms, gradient based algorithm is less sensitive to the camera view. Finally, the performance is greater dependent on the height of the camera position for center of mass positioning system, as compared to the gradient positioning system but the accuracy of the systems can be improved by increasing the height of the camera. In terms of the speed of processing, the gradient positioning system is faster than the center of mass positioning system. The first algorithm, based on center of mass has 89.75\% accuracy with a standard deviation of 3 pixels and the second algorithm has an accuracy of 92.26\%. Accuracy of the system is estimated from the number of false detected positions.
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Automatické polohování zpětného zrcátka / Automatic positioning of the rear view mirrorNávara, Marek January 2016 (has links)
This thesis solves design of functional device that will be able to automatically positioning back view mirrors according to the positio of driver face. Measuring position of the face provides stereovision of two webacams. The device is based on a computer Raspberry Pi 2 with designed expansion board. The created prototype can follow set view int the mirror with accuracy up to 7 cm (horizontally up to 5cm) in level of rear corner of a car. The results of this project validate design of automatic positioning mirror and it can be basis for specific implementations of the device in car.
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