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This thesis presents a skillful robotic wrist system using a visual servo control technique to demonstrate dexterity of the mechanical wrist from the viewpoint of the table tennis. A ball and plate system is chosen as the first stage of this long-term project. A two degrees-of-freedom robotic wrist with an acrylic plate attached as the end effector is developed. A visual feedback control system is implemented with a web cam and a personal computer to acquire the ball's position. In order to implement decision making for changing orientation of the plate, a Linear Quadratic Regulator (LQR) is designed. As a result, the ball can be balanced at specific positions. Experimental results exhibit preliminary and promising achievement. Based on this progress, further improvement and deeper exploration can be carried on in the future.

Generally  cameras  are  used  for  area  based  surveillance,  but  with  advancement  in  technology, cameras  can  be  employed  for wide  area  space  surveillance  (volumetric space surveillance). The volumetric systems require a number of cameras in order to cover a large area. Single panoramic cameras  do  not  provide  required  functionality  for  wide  area  space  surveillance  and Pan-Tile-Zoom (PTZ) cameras do not either cover wide areas.   To  meet  this challenge,  we  propose  a  cost  effective smart volumetric  surveillance system  which utilizes smaller number of cameras in order to provide a coverage of 360 degree. A test case used for this system includes detection of birds in the wind farms. The proposed approach provides a solution  for recording/preventing collision  of  birds  with  wind turbine. To  realize  the  system, a model is developed with two camera nodes. This model provides a 360 degree conical volumetric space coverage. The  system is  utilizing  a  servo  motor  with  capability  of  changing  speed  and arduino  embedded  platform for  controlling  different  functionality. After  triggering  the  camera nodes from arduino, software perform the image analysis.  This  cost  effective  and  wide  area  surveillance  system  consumes at  least half lower  power as compared  to traditional  linear  systems with  eight  cameras. It  is  worth  noting  that  the system provides  conical  shaped  area coverage  of  200  square  meters  with  height ranging  from approximately 40 to 100 meters. The system would capture images in raw format in local storage and  the test  results  show  that  saving  images  with  PNG  format  requires a small  memory  size  as compared  to BMP  and TIFF.    Experiment  results  indicate  that  surveillance  system  can  be effectively employed for detecting birds in opening places.

This thesis presents a visual servo control scheme for a ball-and-plate system with a maze. The maze built on the plate forms obstacles for the ball and increases variety and complexity of its environment. The ball-and-plate system is a two degrees-of-freedom robotic wrist with an acrylic plate attached as the end effector. By using image processing techniques, the ball¡¦s position is acquired from the visual feedback, which was implemented with a webcam and a personal computer. A fuzzy controller, which provides dexterity of the robotic wrist, is designed to decide the slope angles of the plate to guide the ball to a designated target spot. Using the method of distance transform, the path planning based on the current position of the ball is conducted to find the shortest path toward the target spot. Besides, a relaxed path, appears to be more suitable for actual applications, is provided by the obstacle¡¦s expansion approach. Experimental results show that the presented control framework successfully leads the ball to pass through the maze and arrive at target spot. The visual servo control scheme works effectively in both stabilization and tracking control. Based on this preliminary achievement, further improvement and deeper exploration on related research topics can be carried on in the future.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: This thesis presents work completed on the design of control and vision components for use in a monocular vision-based human-following robot. The use of vision in a controller feedback loop is referred to as vision-based or visual servo control. Typically, visual servo techniques can be categorised into imagebased visual servoing and position-based visual servoing. This thesis discusses each of these approaches, and argues that a position-based visual servo control approach is more suited to human following. A position-based visual servo strategy consists of three distinct phases: target recognition, target pose estimation and controller calculations. The thesis discusses approaches to each of these phases in detail, and presents a complete, functioning system combining these approaches for the purposes of human following. Traditional approaches to human following typically involve a controller that causes platforms to navigate directly towards targets, but this work argues that better following performance can be obtained through the use of a controller that incorporates target orientation information. Although a purely direction-based controller, aiming to minimise both orientation and translation errors, suffers from various limitations, this thesis shows that a hybrid, gain-scheduling combination of two traditional controllers offers better targetfollowing performance than its components. In the case of human following the inclusion of target orientation information requires that a definition and means of estimating a human’s orientation be available. This work presents a human orientation measure and experimental results to show that it is suitable for the purposes of wheeled platform control. Results of human following using the proposed hybrid, gain-scheduling controller incorporating this measure are presented to confirm this. / AFRIKAANSE OPSOMMING: Die ontwerp van ’n visiestelsel en beheer-komponente van ’n enkel-kamera robot vir die volging van mense word hier aangebied. Die gebruik van visuele terugvoer in die beheerlus word visie-gebaseerde of visuele servobeheer genoem. Visuele servobeheer tegnieke kan tipies onderskei word tussen beeld-gebaseerde servobeheer en posisie-gebaseerde visuele servobeheer. Altwee benaderings word hier bespreek. Die posisie-gebaseerde benadering word aanbeveel vir die volging van mense. Die posisie-gebaseerde servobeheertegniek bestaan uit drie duidelike fases: teiken herkenning, teiken oriëntasie bepaling en die beheerder berekeninge. Benaderings tot elk van hierdie fases word hier in detail bespreek. Dan word ’n volledige funksionele stelsel aangebied wat hierdie fases saamvoeg sodat mense gevolg kan word. Meer tradisionele benaderings tot die volging van mense gebruik tipies ’n beheerder wat die platvorm direk laat navigeer na die teikens, maar hier word geargumenteer dat beter werkverrigting verkry kan word deur ’n beheerder wat die teiken oriëntasie inligting ook gebruik. ’n Suiwer rigting-gebaseerde beheerder, wat beide oriëntasie en translasie foute minimeer, is onderhewig aan verskeie beperkings. Hier word egter aangetoon dat ’n hibriede, aanwinsskedulerende kombinasie van die twee tradisionele beheerders beter teikenvolging werkverrigting bied as die onderliggende twee tegnieke. In die geval van die volging van mense vereis die insluiting van teiken oriëntasie inligting dat ’n definisie van die persoon se oriëntasie beskikbaar is en dat dit geskat kan word. ’n Oriëntasie maatstaf vir mense word hier aangebied en dit word eksperimenteel getoon dat dit geskik is om ’n platvorm met wiele te beheer. Die resultate van die volging van mense wat die voorgestelde hibriede, aanwins-skedulerende beheerder gebruik, met hierdie maatstaf, word ter ondersteuning aangebied.

Sistemas de visão omnidirecional produzem imagens de 360º do ambiente podendo ser utilizados em navegação, tele-operação e controle servo visual de robôs. Este tipo de sistema dispensa o movimento da câmera para determinada direção de atenção mas requer processamento não convencional da imagem, uma vez que a imagem adquirida se encontra mapeada em coordenadas polares não lineares. Uma maneira efetiva de se obter uma imagem em um sistema omnidirecional é com o uso combinado de lentes e espelhos. Várias formas de espelhos convexos podem ser utilizadas montando-se uma câmera com o seu eixo óptico alinhado com o centro do espelho. Dentre as formas usadas, tem-se os cônicos, parabólicos, hiperbólicos e esféricos. Neste trabalho foi implementado um sistema de visão omnidirecional utilizando um espelho hiperbólico. Este sistema de visão desenvolvido é embarcado em um robô móvel e aplicado em uma tarefa de controle. A tarefa de controle de interesse neste trabalho é a de fazer com que o robô mantenha uma distância constante de um determinado alvo móvel. Esta tarefa é realizada com a realimentação em tempo real de informações visuais do alvo obtidas pelo sistema de visão para controle do robô utilizando uma abordagem de controle servo visual. / Omnidirectional vision systems can get images with a 360-degree of field of view. This type of system is very well suited for tasks such as robotic navigation, tele-operation and visual servoing. Such systems do not require the movement of the camera to the direction of attention of the robot. On the other hand, it requires a non-conventional image processing as the image captured by this vision system is mapped on a non-linear polar coordinate system. One effective way to obtain an image in an omnidirectional system is through the use of lenses and mirrors. Several different shapes of convex mirrors can be used, mounting the center of the mirror aligned with the camera optical axis. The most commonly used mirror shapes are conic, parabolic, hyperbolic and spherical. In this work a hyperbolical mirror was used to build an omnidirectional vision system. This system was mounted on a mobile robot and used in a control task. The task of interest here is the tracking in real time of a moving target keeping the distance between the robot and the target constant. This task is accomplished with data acquisition from the omnidirectional vision system, that is used as feedback to control the mobile robot in a visual servo approach.

Sistemas de visão omnidirecional produzem imagens de 360º do ambiente podendo ser utilizados em navegação, tele-operação e controle servo visual de robôs. Este tipo de sistema dispensa o movimento da câmera para determinada direção de atenção mas requer processamento não convencional da imagem, uma vez que a imagem adquirida se encontra mapeada em coordenadas polares não lineares. Uma maneira efetiva de se obter uma imagem em um sistema omnidirecional é com o uso combinado de lentes e espelhos. Várias formas de espelhos convexos podem ser utilizadas montando-se uma câmera com o seu eixo óptico alinhado com o centro do espelho. Dentre as formas usadas, tem-se os cônicos, parabólicos, hiperbólicos e esféricos. Neste trabalho foi implementado um sistema de visão omnidirecional utilizando um espelho hiperbólico. Este sistema de visão desenvolvido é embarcado em um robô móvel e aplicado em uma tarefa de controle. A tarefa de controle de interesse neste trabalho é a de fazer com que o robô mantenha uma distância constante de um determinado alvo móvel. Esta tarefa é realizada com a realimentação em tempo real de informações visuais do alvo obtidas pelo sistema de visão para controle do robô utilizando uma abordagem de controle servo visual. / Omnidirectional vision systems can get images with a 360-degree of field of view. This type of system is very well suited for tasks such as robotic navigation, tele-operation and visual servoing. Such systems do not require the movement of the camera to the direction of attention of the robot. On the other hand, it requires a non-conventional image processing as the image captured by this vision system is mapped on a non-linear polar coordinate system. One effective way to obtain an image in an omnidirectional system is through the use of lenses and mirrors. Several different shapes of convex mirrors can be used, mounting the center of the mirror aligned with the camera optical axis. The most commonly used mirror shapes are conic, parabolic, hyperbolic and spherical. In this work a hyperbolical mirror was used to build an omnidirectional vision system. This system was mounted on a mobile robot and used in a control task. The task of interest here is the tracking in real time of a moving target keeping the distance between the robot and the target constant. This task is accomplished with data acquisition from the omnidirectional vision system, that is used as feedback to control the mobile robot in a visual servo approach.

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This thesis derives an vision based feedback control strategy for a class of uncertain projector-camera systems that are used to animate two dimensional projected images on complex, three dimensional, articulated target objects. The target object of the robotic system is articulated using an open loop control strategy that generates a desired sequence of target poses that are designed using commercially available geometric modeling software. The ideal or desired image sequences are subsequently rendered in the geometric modeling software using an ideal camera/projector pose and ideal intrinsic parameter camera model. The rendered imagery from the ideal camera and projector pose are subsequently used to define tracking performance for the feedback control of the camera and projector. Uncertainty in actuator models of the camera and projector actuator subsystems in this paper includes contributions due to imprecision in camera pose and in intrinsic camera parameters. A feedback control strategy is derived that employs pixel coordinates of multiple tracked feature points in the target image sequence for pose estimation and tracking control problems. We establish sufficient conditions that guarantee the convergence and asymptotic stability of the pose estimation and tracking control problems for the class of uncertain, nonlinear systems studied in this thesis. Several numerical studies are summarized in the thesis that provide confidence in the derived theoretical results and further suggest robustness of the control strategy for the considered uncertainty class. / Master of Science