Search results for "Omnidirectional antenna"
showing 10 items of 13 documents
Omnidirectional vision for UAV: applications to attitude, motion and altitude estimation for day and night conditions
2012
International audience; This paper presents the combined applications of omnidirectional vision featuring on its application to aerial robotics. Omnidirectional vision is first used to compute the attitude, altitude and motion not only in rural environment but also in the urban space. Secondly, a combination of omnidirectional and perspective cameras permits to estimate the altitude. Finally we present a stereo system consisting of an omnidirectional camera with a laser pattern projector enables to calculate the altitude and attitude during the improperly illuminated conditions to dark environments. We demonstrate that omnidirectional camera in conjunction with other sensors is suitable cho…
Visual tracking with omnidirectional cameras: an efficient approach
2011
International audience; An effective technique for applying visual tracking algorithms to omni- directional image sequences is presented. The method is based on a spherical image representation which allows taking into account the distortions and nonlinear resolution of omnidirectional images. Experimental results show that both deterministic and probabilistic tracking methods can effectively be adapted in order to robustly track an object with an omnidirectional camera.
Adapted Approach for Omnidirectional Egomotion Estimation
2011
Egomotion estimation is based principally on the estimation of the optical flow in the image. Recent research has shown that the use of omnidirectional systems with large fields of view allow overcoming the limitation presented in planar-projection imagery in order to address the problem of motion analysis. For omnidirectional images, the 2D motion is often estimated using methods developed for perspective images. This paper adapts motion field calculated using adapted method which takes into account the distortions existing in the omnidirectional image. This 2D motion field is then used as input to the egomotion estimation process using spherical representation of the motion equation. Expe…
Extrinsic calibration of heterogeneous cameras by line images
2014
International audience; The extrinsic calibration refers to determining the relative pose of cameras. Most of the approaches for cameras with non-overlapping fields of view (FOV) are based on mirror reflection, object tracking or rigidity constraint of stereo systems whereas cameras with overlapping FOV can be calibrated using structure from motion solutions. We propose an extrinsic calibration method within structure from motion framework for cameras with overlapping FOV and its extension to cameras with partially non-overlapping FOV. Recently, omnidirectional vision has become a popular topic in computer vision as an omnidirectional camera can cover large FOV in one image. Combining the g…
A new bi-faced log periodic printed antenna
2005
In this paper, a new design of a broadband planar printed antenna based on the academic log periodic antenna is presented. The antenna consists of a series of printed dipoles, distributed on both faces of the substrate. Some configurations are explored, with a different number of printed dipoles. These are designed, simulated, fabricated, and measured. The calculated and measured return losses and radiation patterns are presented. The utility of the proposed antenna associated with its frequency bandwidth is better than 80%. The measured absolute gain is 6.5 dBi, and the front-to-back ratio is around 8 dB. The presented antenna should find wide applications in wireless communication systems…
Creating an ethernet communication between a Simatic S7-1200 PLC and Arduino Mega for an omnidirectional mobile platform and industrial equipment
2020
Abstract The degree of automation in the industry increases more and more every year, trying to reduce more and more or even eliminate the collaboration with the human operator. The basis of all automatic industrial equipment is PLCs. This paper presents a method of extending the number of inputs and outputs of a Siemens Simatic S7-1200 PLC, using an Arduino Mega development board and an Ethernet communication. Following the realization of this communication, the number of inputs and outputs will increase considerably, being able to connect various sensors used for the construction of an omnidirectional mobile platform, but also for equipment for industry. The advantages of using this commu…
Design of a modular locomotion system for autonomous mobile robots
2021
Autonomous mobile robots are becoming more popular today and are successfully integrated into many civil and industrial projects. In the industrial sectors flexibility and modularity have an important role, so the production can be diversified and achieved with low costs. This paper presents the conceptual and functional design of a modular locomotion system for an autonomous mobile platform that can be configured according to the needs of the industrial environment it serves. The architecture of the locomotion system is based on a spring suspension system and three types of wheels: conventional wheels, omnidirectional wheels and mechanum wheels. The calculations for the chosen suspension s…
A space-division time-division multiple access scheme for high throughput provisioning in WLANs
2005
Directional antennas may dramatically increase the capacity of a Wireless LAN by allowing several stations to simultaneously communicate. Since deployment of directive/smart antennas on the customer's terminals is awkward (for technological, cost, robustness, and convenience reasons) it is of interest to deploy advanced antenna solutions only at the Access Point. When omnidirectional transmissions are used at the Mobile Stations, the asynchronous nature of the 802.11 MAC handshake structurally limits the possibility to exploit spatial reuse. Significant throughput enhancements can be achieved only at the expense of redesigning (part of) the 802.11 MAC protocol: mainly a form of synchronizat…
Minimization of a rectangular patch using genetic algorithms
2002
In recent years, the miniaturization of antennas have become more and more important, especially in connection with subscriber transceivers for cellular systems. Due to the multiple scattering environments and the almost indefinable operating scenario, the crosspolarization characteristics of the antenna are less important, however its physical size is critical. The attempts to reduce the physical size of the antenna made in the past, used classical methods, such as embedding the antenna in a dielectric medium of a high permittivity, adding a resistive element in series with the antenna, etc., but little effort was invested in simply generating other geometries, which by their intrinsic pro…
Tuneable multicoloured patterns from photonic cross-communication between cholesteric liquid crystal droplets
2014
Monodisperse droplets of planar-aligned cholesteric (N*) liquid crystal exhibit an intriguing capacity for photonic cross-communication, giving rise to colourful patterns that depend sensitively on the N* pitch, droplet positions and illuminated area. The phenomenon results from a combination of omnidirectional selective reflection of N* droplets—which thus act as spherically symmetric self-assembled photonic crystals—and total internal reflection at the continuous phase surface. We outline how the unique optical properties can be employed in numerous applications.