Current Issue : July - September Volume : 2019 Issue Number : 3 Articles : 5 Articles
To avoid degradation of navigation performance in the navigation warfare environment,\nthe multi-radio integrated navigation system can be used, in which all available radio navigation\nsystems are integrated to back up Global Navigation Satellite System (GNSS) when the GNSS is not\navailable. Before real-time multi-radio integrated navigation systems are deployed, time and cost\ncan be saved when the modeling and simulation (M&S) software is used in the performance\nevaluation. When the multi-radio integrated navigation system M&S is comprised of independent\nfunction modules, it is easy to modify and/or to replace the function modules. In this paper, the\nM&S software design method was proposed for multi-radio integrated navigation systems as a\nGNSS backup under the navigation warfare. The M&S software in the proposed design method\nconsists of a message broker and function modules. All the messages were transferred through the\nmessage broker in order to be exchanged between the function modules. The function modules in\nthe M&S software were independently operated due to the message broker. A message brokerbased\nM&S software was designed for a multi-radio integrated navigation system. In order to show\nthe feasibility of the proposed design method, the M&S software was implemented for Global\nPositioning System (GPS), Korean Navigation Satellite System (KNSS), enhanced Long range\nnavigation (eLoran), Loran-C, and Distance Measuring Equipment/Very high-frequency\nOmnidirectional Radio range (DME/VOR). The usefulness of the proposed design method was\nshown by checking the accuracy and availability of the GPS only navigation and the multi-radio\nintegrated navigation system under the attack of jamming to GPS....
As the basis of animalsâ?? natal homing behavior, path integration can continuously provide current position information relative to\nthe initial position. Some neurons in freely moving animalsâ?? brains can encode current positions and surrounding environments\nby special firing patterns. Research studies show that neurons such as grid cells (GCs) in the hippocampus of animalsâ?? brains are\nrelated to the path integration. They might encode the coordinate of the animalâ??s current position in the same way as the residue\nnumber system (RNS) which is based on the Chinese remainder theorem (CRT). Hence, in order to provide vehicles a bionic\nposition estimation method, we propose a model to decode the GCsâ?? encoding information based on the improved traditional selforganizing\nmap (SOM), and this model makes full use of GCsâ?? firing characteristics. The details of the model are discussed in this\npaper. Besides, the model is realized by computer simulation, and its performance is analyzed under different conditions.\nSimulation results indicate that the proposed position estimation model is effective and stable....
In ecological research, a key interest is to explore movement patterns of individual\norganisms across different spatial scales as one driver of biotic interactions. While various methods\nexist to detect and record the presence and movements of individuals in combination with UAS,\naddressing these for smaller animals, such as insects, is challenging and often fails to reveal\ninformation on potential interactions. Here, we address this gap by combining the UAS-based\ndetection of small tracers of fluorescent dyes by means of a simple experiment under field conditions\nfor the first time. We (1) excited fluorescent tracers utilizing an UV radiation source and recorded\nimages with an UAS, (2) conducted a semi-automated selection of training and test samples to\n(3) train a simple SVM classifier, allowing (4) the classification of the recorded images and (5) the\nautomated identification of individual traces. The tracer detection success significantly decreased\nwith increasing altitude, increasing distance from the UV radiation signal center, and decreasing\nsize of the fluorescent traces, including significant interactions amongst these factors. As a first\nproof-of-principle, our approach has the potential to be broadly applicable in ecological research,\nparticularly in insect monitoring....
A recently proposed navigation methodology for aerial platforms based on the vehicle\ndynamic model (VDM) has shown promising results in terms of navigation autonomy. Its practical\nrealization requires that control inputs are related to the same absolute time frame as inertial\nmeasurement unit (IMU) data and all other observations when available (e.g., global navigation\nsatellite system (GNSS) position, barometric altitude, etc.). This study analyzes the (non-) tolerances\nof possible delays in control-input command with respect to navigation performance on a fixed-wing\nunmanned aerial vehicle (UAV). Multiple simulations using two emulated trajectories based on real\nflights reveal the vital importance of correct time-tagging of servo data while that of motor data\nturned out to be tolerable to a considerably large extent....
TheCarrier-Phase-DerivedDoppler (CPDD) observation is an important type of observation for high-precision standalone velocity\nestimation (SVE) with the BeiDou Navigation Satellite System (BDS) receiver. The CPDD observation is susceptible to receiver\nclock jump, carrier-phase cycle slips, and multipath error. How to improve the accuracy and reliability of the SVE method based\non the CPDD observation has become an urgent problem to be solved. Based on the Velocity Domain Selective Fusion (VDSF)\nstrategy, this paper proposes the VDSF-ARUKF method for accuracy and reliability improvement of the SVE results of the original\nARUKF method. In this improved ARUKF method, the CPDD observation and the raw Doppler observation are fused together\nbased on the detection statistic under the framework of the Adaptively Robust Unscented Kalman Filter (ARUKF). Based on actual\nobservations of the BDS receiver, a set of testing experiments were designed to verify the effectiveness of this improved ARUKF\nmethod. The experimental results show that the SVE method of the BDS receiver based on the VDSF-ARUKF can improve the\naccuracy and reliability of the ARUKF SVE results of the BDS receiver. In the case of multidimensional gross errors in the CPDD\nobservations, the VDSF-ARUKF method can still obtain the SVE results with the highest accuracy on the order of several \n10-2m/s when compared with the VDFF-ARUKF method and the ARUKF method using the CPDD observations....
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