A real-time/low-cost DOA estimation system based on Rotman lens array antenna

Author(s):  
Yan-Yun Lin ◽  
Wen-Jiao Liao
Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4093
Author(s):  
Alimed Celecia ◽  
Karla Figueiredo ◽  
Marley Vellasco ◽  
René González

The adequate automatic detection of driver fatigue is a very valuable approach for the prevention of traffic accidents. Devices that can determine drowsiness conditions accurately must inherently be portable, adaptable to different vehicles and drivers, and robust to conditions such as illumination changes or visual occlusion. With the advent of a new generation of computationally powerful embedded systems such as the Raspberry Pi, a new category of real-time and low-cost portable drowsiness detection systems could become standard tools. Usually, the proposed solutions using this platform are limited to the definition of thresholds for some defined drowsiness indicator or the application of computationally expensive classification models that limits their use in real-time. In this research, we propose the development of a new portable, low-cost, accurate, and robust drowsiness recognition device. The proposed device combines complementary drowsiness measures derived from a temporal window of eyes (PERCLOS, ECD) and mouth (AOT) states through a fuzzy inference system deployed in a Raspberry Pi with the capability of real-time response. The system provides three degrees of drowsiness (Low-Normal State, Medium-Drowsy State, and High-Severe Drowsiness State), and was assessed in terms of its computational performance and efficiency, resulting in a significant accuracy of 95.5% in state recognition that demonstrates the feasibility of the approach.


Author(s):  
Alexander A. Maltsev ◽  
Valentin M. Seleznev ◽  
Alexander S. Rulkov ◽  
Olesya V. Bolkhovskaya

Introduction. Currently, one of the most promising approaches of the 5th generation mobile wireless systems development is the deployment of heterogeneous networks based on existing LTE cellular systems with large and small cells. The main elements of such networks can be small low cost relay stations equipped with highly directional steerable antenna systems to connect small cells with LTE base station serving macrocell. Objective. Existing solutions are either too expensive or not allowing flexible rearrangement of current information transmission lines. The objective of this work is to develop antenna equipment for low cost relay stations based on simple steerable antenna systems of millimetre wavelength (57-64 GHz), which allow beamsteering in both azimuth and elevation planes. Methods and materials. The developed steerable bifocal lens antenna system is a lens of a special shape made of a high molecular weight polyethylene and integrated with a phased array antenna. A key feature of the designed antenna system is a wide-angle beamsteering in the azimuth plane and ability to adjust the beam in the elevation plane. The calculation of the lens profiles was carried out by means of an approximation of geometrical optics in Matlab, and the main technical characteristics of the lens antenna system were obtained by direct electromagnetic modelling in CST Microwave Studio. Results. The prototype of the steerable bifocal lens-array antenna system is developed and its characteristics are studied. The following technical characteristics are achieved in the 57–64 GHz range: beamsteering in the elevation plane is ±3º, beamsteering in the azimuth plane is ±40º, and antenna gain is from 20 to 27.5 dBi for all angles. Conclusion. It was shown that the developed antenna system can be successfully used as receiving and transmission antenna equipment of small relay stations that transmit information in the frequency range of 57-64 GHz over a distance of 100-300 m.


2013 ◽  
Vol 321-324 ◽  
pp. 528-531
Author(s):  
Jing Ran Wu ◽  
Zhen Guo Sun ◽  
Qi Dong Ma ◽  
Wen Zeng Zhang

An embedded attitude estimation system is developed for the autonomous flight of Quad-Rotor UAVs. The system hardware is composed of a DSP processor and low-cost MEMS sensors including a 3-axis gyroscope and a 3-axis accelerometer. A Complementary Filter fused the advantages of the gyroscope and accelerometer is designed and embedded on the DSP processor to estimate the real-time attitude. Ground testing experiments show that the system could meet the accuracy and robustness requirements for the Quad-Rotor UAVs attitude estimation.


Author(s):  
Gabriel de Almeida Souza ◽  
Larissa Barbosa ◽  
Glênio Ramalho ◽  
Alexandre Zuquete Guarato

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