Dynamic Omnidirectional Vision Localization Using a Beacon Tracker Based on Particle Filter

Autonomous navigation is of primary importance in applications involving the usage of Autonomous Guided Vehicles (AGVs). Vision-based navigation systems provide an interesting option for both indoor and outdoor navigation as they can also be used in environments without an external supporting infrastructure for the navigation, which is unlike GPS, for example. However, the environment has to contain some natural or artificial features that can be observed with the vision system, and these features have to have some relationship to spatial locations in the navigation environment (Cao, 2001). The omnidirectional camera system produces a spherical field of view of an environment. This is particularly useful in vision-based navigation systems as all the images, provided by the camera system, contain the same information, independent of the rotation of the robot in the direction of the optical axis of the camera. This makes the computed image features more suitable for localization and navigation purposes (Hrabar & Sukhatme, 2003; Hampton et al., 2004). The methods proposed have been developed for vision-based navigation of Autonomous Ground Vehicles which utilize an omni-directional camera system as the vision sensor. The complete vision-based navigation system has also been implemented, including the omni-directional color camera system, image processing algorithms, and the navigation algorithms. The actual navigation system, including the camera system and the algorithms, has been developed. The aim is to provide a robust platform that can be utilized both in indoor and outdoor AGV applications (Cauchois et al., 2005; Sun et al., 2004). The fisheye lens is one of the most efficient ways to establish an omnidirectional vision system. The structure of the fisheye lens is relatively dense and well-knit unlike the structure of reflector lenses which consist of two parts and are fragile. (Li et al., 2006; Ying et al., 2006). Omnidirectional vision (omni-vision) holds promise of various applications. We use a fisheye lens upwards with the view angle of 185° to build the omni-directional vision system. Although fisheye lens takes the advantage of an extremely wide angle of view, there is an inherent distortion in the fisheye image which must be rectified to recover the original image. An approach for geometric restoration of omni-vision images has to be considered since an inherent distortion exists. The mapping between image coordinates and physical space parameters of the targets can be obtained by means of the imaging principle on the fisheye lens. Firstly a method for calibrating the omni-vision system is proposed. The method relies on the utilities of a cylinder on which inner wall including several straight O pe n A cc es s D at ab as e w w w .ite ch on lin e. co m