12 research outputs found

    Dual Orthogonal Feed Circular Polarization Array Antenna Using Microstrip Slot Feed Network

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    This paper presents a new circularly polarized microstrip array antenna using dual-orthogonal feed technique. The feed network for 1x2 array is designed using microstrip lines and slot lines by applying double-sided MIC concept effectively. 90 degree phase difference between two orthogonally feed signals os created by choosing appropriate feed point in the feed network to advance one of the feed signals by quarter wavelength (lemda/4) from other. Excellent radiation performance is obtained from this proposed antenna with low cross polar component. The impedence (<-10dB) bandwidth of the array is 9.1% and the 3-dB axial ration bandwidth is 1.85% (9.905GHz to 10.09 GHz). The average  gain is higher than 9dBiC over the 3-dB AR bandwidth. The relation between antenna dimensions and characteristics ia also investigated with a parametric analysis of the antenna

    Design and Implementation of Automated Ankle Foot Orthosis for Foot Drop Patients Using Gait Cycle EMG Analysis

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    Foot drop is known as gait abnormality in which the dropping of the forefoot happens due to the weakness of Tibialis Anterior Muscle for the damage of the common fibular nerve in the anterior portion of the lower leg. In this research, those patients are considered who have foot drop for Guillain–Barré syndrome (GBS). GBS is a peripheral nerve disorder for which bilateral foot drop happens to the patients. So, the aim of this research is to develop an automated Ankle Foot Orthosis (AFO) which will aid the GBS patients in their gait cycle while walking. For the development of this AFO, an EMG analysis has been conducted on both normal people (20 persons, Male 20-45 years) and GBS patients (10 patients, Male 20-45 years) and compared to find out the deviation of the patient’s one from the normal people. The findings of the EMG study show that the stance phase of the gait cycle is not affected by the GBS as correlation coefficient values are in between 0.95 to 1 where the swing phase very much deviates from the normal pattern as the coefficient values are in between 0.6 to 0.7 as well as short swing phase and no heel strike during walking. Considering these, automated AFO has been developed and implemented to test the feasibility and effectiveness on patients. The experimental results show that the effect of GBS on swing phase can be lessened as the value of correlation coefficient increases to 0.85 to 0.9 with long swing phase and proper heel strike on terminal swing phase

    Improved Solar Photovoltaic Array Model with FLC Based Maximum Power Point Tracking

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    This paper presents an improved model of solar photovoltaic (PV) array along with the implementation of fuzzy logic as maximum power point tracking (MPPT). The proposed PV array behavioral model is more accurate and with reduced complexity though considered discrete components. The PV array model was well verified by considering the effect of change of environmental conditions, mainly intensity of solar irradiation (insolation) and temperature. The model was tested by feed a single phase inverter. MPPT control the operating voltage of  PV arrays in order to maximize their power output as a result maximize the array efficiency and minimize  the overall system cost. Using a Fuzzy logic based algorithm, the duty cycle of the converter inserted between source and load is adjusted continuously to track the MPP and compared with the conventional perturb and observed (P&O) method for changing environmental conditions. It was found that the Fuzzy logic based method can track the MPP more precisely and rapidly than the conventional one. In P&O method, if step size of input variable is very small, the accuracy in tracking MPP is sufficient but tracking speed becomes too slow. On the other hand if the step size is increased to imitate the rapidly changing weather conditions, accuracy deteriorates and unexpected results occur due to oscillation around a mean point although tracking speed increased. But in the case of proposed FLC whatever the step size of input variable it best suited to track MPP continuously and accurately. The obtained simulation results validate the competent of the solar PV array model as well as the fuzzy controller.DOI:http://dx.doi.org/10.11591/ijece.v2i6.132

    Single feed circularly polarized crescent-cut and extended corner square microstrip antennas for wireless biotelemetry

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    In this paper, the development of two novel circularly polarized microstrip antennas is thoroughly explained. These antennas are fed by coaxial feeding technique. One of the primary objectives of the proposed work is to tune the antennas to work in ISM band. This frequency band refers to the internationally recognized radio frequency bandwidth which is to be used explicitly for Industrial, Scientific, and Medical applications. Therefore, these antennas would be suitable to use in the field of wireless biotelemetry. Two new antenna design techniques have been introduced to produce circular polarization, and details of these schemes are described. The proposed microstrip antennas are designed and simulated on Advanced Design System (ADS) software. The return loss of the proposed crescent-cut antenna is -19.3 dB at the operating frequency. The extended corner antenna has the return loss of -29.3 dB at the tuned frequency. The simulation results are also presented and discussed

    An improved 2Ă—2 array antenna using both-sided microwave integrated circuit technology for circular polarization

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    A circularly polarized microstrip patch array antenna using both-sided microwave integrated circuit (MIC) technology with a triple feed network has been proposed in this article. The antenna elements, feed structure and both-sided MIC technology are used and arranged in such a way to obtain circular polarization alongside high gain without using an external matching circuit. The 50 Ω microstrip line is used to energize the antenna where the antenna’s total feed network is made up of both series and parallel combinations of microstrip and slot line. The antenna was realized using Teflon glass fiber substrate (εr)=2.15 with a thickness of 0.8 mm. The antenna has some splendid parameters including S11 of less than -35 dB, a gain of 12 dBi with an omnidirectional pattern and an axial ratio of 0.7 dB at the operating frequency. The antenna possesses a bandwidth of 430 MHz (4.22%) after operating at X-band in the frequency spectrum. The antenna’s simulated parameters were investigated with the help of advanced design system (ADS) simulation software in microwave momentum mode

    Design and Characterization of a Current Assisted Photo Mixing Demodulator for Tof Based 3d Cmos Image Sensor

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    Due to the increasing demand for 3D vision systems, many efforts have been recently concentrated to achieve complete 3D information analogous to human eyes. Scannerless optical range imaging systems are emerging as an interesting alternative to conventional intensity imaging in a variety of applications, including pedestrian security, biomedical appliances, robotics and industrial control etc. For this, several studies have reported to produce 3D images including stereovision, object distance from vision system and structured light source with high frame rate, accuracy, wide dynamic range, low power consumption and lower cost. Several types of optical techniques for 3D imaging range measurement are available in the literature, among them one of the most important is time-of-flight (TOF) principle that is intensively investigated. The third dimension, i.e. depth information, can be determined by correlating the reflected modulated light signal from the scene with a reference signal synchronous with the light source modulation signal. CMOS image sensors are capable of integrating the image processing circuitry on the same chip as the light sensitive elements. As compared to other imaging technologies, they have the advantages of lower power consumption and potentially lower price. The merits make this technology competent for the next-generation solid-state imaging applications. However, CMOS process technologies are developed for high-performance digital circuits. Different types of 3D photodetectors have been proposed for three-dimensional imaging. A major performance improvement has been found in the adoption of inherently mixing detectors that incorporate the role of detection and demodulation in a single device. Basically, these devices use a modulated electric field to guide the photo generated charge carriers to different collection sites in phase with a modulation signal. One very promising CMOS photonic demodulator based on substrate current modulation has recently been proposed. In this device the electric field penetrates deeper into the substrate, thus enhancing the charge separation and collection mechanism. A very good sensitivity and high demodulation efficiency can be achieved. The objective of this thesis has been the design and characterization of a Current Assisted Photo mixing Demodulator (CAPD) to be applied in a TOF based 3D CMOS sensing system. At first, the experimental investigation of the CAPD device is carried out. As a test vehicle, 10×10 pixel arrays have been fabricated in 0.18µm CMOS technology with 10×10 µm2 pixel size. The main properties of CAPD devices, such as the charge transfer characteristic, modulation contrast, noise performance and non-linearity problem, etc. have been simulated and experimentally evaluated. Experimental results demonstrate a good DC charge separation efficiency and good dynamic demodulation capabilities up to 45MHz. The influence of performance parameters such as wavelength, modulation frequency and voltage on this device is also discussed. This test device corresponds to the first step towards incorporating a high resolution TOF based 3D CMOS image sensor. The demodulator structure featuring a remarkably small pixel size 10 × 10 µm2 is used to realize a 120 × 160 pixel array of ranging sensor fabricated in standard 0.18µm CMOS technology. Initial results demonstrate that the demodulator structure is suitable for a real-time 3D image sensor. The prototype camera system is capable of providing real-time distance measurements of a scene through modulated-wave TOF measurements with a modulation frequency 20 MHz. In the distance measurement, the sensor array provides a linear distance range from 1.2m to 3.7m with maximum accuracy error 3.3% and maximum pixel noise 8.5% at 3.7m distance. Extensive testing of the device and prototype camera system has been carried out to gain insight into the characteristics of this device, which is a good candidate for integration in large arrays for time-of-flight based 3D CMOS image sensor in the near future

    Current Assisted Photonic Mixing Demodulator implemented in 0.18µm Standard CMOS Technology

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    CMOS image sensors integrate the image processing circuitry on the same chip as the light sensitive elements. Recently, lots of effort has been concentrated to create a standard CMOS photonic demodulator. A CMOS based current assisted photonic mixing demodulator is described in this paper. As a test vehicle, 10Ă—10 pixel arrays in two different geometries have been fabricated with a 0.18ÎĽm CMOS technology. Remarkably small pixel size of 10Ă—10 ÎĽm2 has been achieved. Preliminary experimental results demonstrate a good DC charge separation efficiency close to 100% and good demodulation capabilities up to 35MHz. The measurement results are compared to the performance of two different device array structures. These test devices represent the first step towards integrating a high resolution TOF based 3D CMOS image sensor

    Internet of things based fall detection and heart rate monitoring system for senior citizens

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    Falls cause the maximum number of injuries, deaths, and hospitalizations due to injury for senior citizens worldwide. So, fall detection is essential in the health care of senior citizens. Present methods lack either accuracy or comfortability. The design of fall detection and heart rate monitoring system for senior citizens has been presented in this paper. The hardware interface includes wearable monitoring devices based on a tri-axial accelerometer and Bluetooth module that makes a wireless connection by software interface (mobile application) to the caregiver. Global positioning system (GPS) can also track the location of the elder. For detecting falls accurately, an effective fall detection algorithm is developed and used. The performance parameters of the fall detection system are accuracy (97.6%), sensitivity (92.8%), and specificity (100%). A pulse sensor is used for monitoring the heart rate of the elder. The device is put on the hips to increase comfortability. Whenever the elder's fall is detected, the device can send information on fall data and heart rate with location to the respective caregiver successfully. So, this device can minimize the injury and health cost of a fallen person as a victim can get help within a short time

    TOF-range image sensor in 0.18 micron CMOS technology based on current assisted photonic demodulators

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    We report on a 0.18micron CMOS range image sensor with 120Ă—160 array of 10Ă—10micron2 photonic demodulation pixels allowing for real-time 3D imaging with a worst-case accuracy of 3.3% in the distance interval [1.2-3.7] m
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