Estimation and prediction of the vehicle's motion basedon visual odometry and Kalman filter

Proceeding of: 14th International Conference, ACIVS 2012, Brno, Czech Republic, September 4-7, 2012The movement of the vehicle is an useful information for different applications, such as driver assistant systems or autonomous vehicles. This information can be known by different methods, for instance, by using a GPS or by means of the visual odometry. However, there are some situations where both methods do not work correctly. For example, there are areas in urban environments where the signal of the GPS is not available, as tunnels or streets with high buildings. On the other hand, the algorithms of computer vision are affected by outdoor environments, and the main source of difficulties is the variation in the ligthing conditions. A method to estimate and predict the movement of the vehicle based on visual odometry and Kalman filter is explained in this paper. The Kalman filter allows both filtering and prediction of vehicle motion, using the results from the visual odometry estimation.This work was also supported by Spanish Government through the CICYT projects FEDORA (Grant TRA2010-20255-C03-01), Driver Distraction Detector System (Grant TRA2011-29454-C03-02) and by CAM through the projects SEGVAUTO-II.Publicad

Influence of the bias-voltage on the anchoring energy for nematic liquid crystals

The influence of the bias-voltage on the anisotropic part of the nematic surface energy is analyzed. The experimental data show a strong dependence of the anchoring strength on the bias-voltage when the electrodes of the nematic cell are covered with WO3. The observed dependence can be interpreted taking into account the ions dissolved in the liquid crystal. We propose a model in which the effect of the bias-voltage is to collect the ions near the electrodes, in a surface layer whose thickness is of the order of the Debye’s screening length. The surplus of electric field due to this ions confinement gives rise to an electrostatic contribution to the total energy that can be considered as a surface energy. The proposed model is in good agreement with the experimental data. The model is used to interpret the observed independence of the anchoring strength on the bias-voltage when the indium-oxide electrode is covered with a film of polyimide, or it is without any covering. The influence of a charge emission from the electrodes under the bias voltage on the anchoring energy is also analyzed. Possible applications of the observed phenomenon are discussed

Ball Detection and Predictive Ball Following Based on a Stereoscopic Vision System

In this paper we describe an efficient software architecture for object-tracking, based on a stereoscopic vision system, that has been applied to a mobile robot controlled by a PC. After analyzing the epipolar rectification required to correct the original stereo-images, it is described a new valid and efficient algorithm for ball recognition (indeed circle detection) which is able to work in different lighting conditions and in a manner faster than some modified versions of Circle Hough Transform. Then, we show that stereo vision, besides giving an optimum estimation of the 3D position of the object, is useful to remove lots of the false identifications of the ball, thanks to the advantages of epipolar constraint. Finally, we describe a new strategy for ball following, by a mobile robot, which is able to look for the object whenever it comes out of the cameras view, by taking advantage of a block matching method similar to that of MPEG Video

Precise Bearing Angle Measurement Based on Omnidirectional Conic Sensor and Defocusing

Recent studies on multi-robot localization have shown that the uncertainty of robot location may be considerably reduced by optimally fusing odometry and the relative angles of sight (bearing) among the team members. However, the latter requires the capability for each robot of detecting the other members up to large distances and wide field of view. Furthermore, robustness and precision in estimating the relative angle of sight is of high importance. In this paper we show how all of the these requirements may be achieved by employing an omnidirectional sensor made up of a conic mirror and a simple webcam. We use different colored lights to distinguish the robots and optical defocusing to identify the lights. We show that defocusing increases the detection range up to several meters, compensating the decay of resolution related to the omnidirectional view, without losing robustness and precision. To allow a real time implementation of light tracking, we use a recent tree-based union find technique for color segmentation and region merging. We also present a self-calibration technique based on an Extended Kalman Filter to derive the intrinsic parameters of the robot-sensor system. The performance of the approach is shown through experimental results

Has covid-19 delayed the diagnosis and worsened the presentation of type 1 diabetes in children?

OBJECTIVE To evaluate whether the diagnosis of pediatric type 1 diabetes or its acute complications changed during the early phase of the coronavirus disease 2019 (COVID-19) pandemic in Italy. RESEARCH DESIGN AND METHODS This was a cross-sectional, web-based survey of all Italian pediatric diabetes centers to collect diabetes, diabetic ketoacidosis (DKA), and COVID-19 data in patients presenting with new-onset or established type 1 diabetes between 20 February and 14 April in 2019 and 2020. RESULTS Fifty-three of 68 centers (77.9%) responded. There was a 23% reduction in new diabetes cases in 2020 compared with 2019. Among those newly diagnosed patients who presented in a state of DKA, the proportion with severe DKA was 44.3% in 2020 vs. 36.1% in 2019 (P 5 0.03). There were no differences in acute complications. Eight patients with asymptomatic or mild COVID-19 had laboratory-confirmed severe acute respiratory syndrome coronavirus 2. CONCLUSIONS The COVID-19 pandemic might have altered diabetes presentation and DKA severity. Preparing for any “second wave” requires strategies to educate and reassure parents about timely emergency department attendance for non–COVID-19 symptoms