Department of Electrical Engineering

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IIT Jodhpur

Stride rate and length are monitored by physicians to identify abnormalities in the patients' gait. These are also important parameters for athletes. Lab based video recordings are used for monitoring while new methods utilize inertial sensors. These sensors require a lot of sensed data processing consequently power is utilized. A new class of methods using wireless sensing has been introduced recently. These methods either require a lot of sensing nodes or are non-ubiquitous while others have used received signal strength as monitoring parameter which is quite unstable. We have proposed a novel ubiquitous node deployment on the human body itself to minimize the environmental noise interference. Walking parameters like stride rate, stride length have been estimated using wireless sensing physical layer channel state information (CSI). The human body acts as an obstacle for the wireless signals due to frequency selective multipath fading. We argue that this fading has a unique signature respective to the activity performed by humans which can be estimated using CSI. This signature should be best observed when both the sender and receiver nodes are deployed on the body due to decreased environmental interference. We have trained the system to identify these signatures and deduce corresponding gait parameters. In this paper we are only able to summarize the new idea with initial findings. We are in the process to understand the signal morphology for finer measurements. © 2015 IEEE.

World University root node

2015, 9th International Conference on Signal Processing and Communication Systems, ICSPCS 2015 - Proceedings

Walking parameters estimation through channel state information: Preliminary results

In this paper, a novel transition from co-axial probe-to-substrate integrated waveguide (SIW) and from SIW-to-dielectric image line (DIL) is proposed in Ku-band (12-18 GHz). The proposed transition is designed on a single substrate and thus eliminates complex multi-layer fabrication process for implementation of dielectric image line two port network. The proposed design is simulated on Ansoft HFSS and exhibits wide bandwidth performance. For probe-to-SIW back-to-back transition, the relative bandwidth (-20dB) is 38.5% and for back-to-back transition from probe-to-SIW and from SIW-to-DIL, the relative bandwidth (-15dB) is 24.5%. The insertion loss is better than 3.2 dB throughout the operating bandwidth. Detailed studies on dimensions of the matching network is also discussed. The results are also verified by using CST Microwave Studio. © 2015 EurAAP.

2015 9th European Conference on Antennas and Propagation, EuCAP 2015

Efficient probe excitation of dielectric image line using substrate integrated waveguide based matching network

Single mode - Multimode - Multimode (SMm) fiber structure provides a simple and cost effective method for exciting a single radial mode in a multimode fiber (MMF). The structure can be effectively utilized in improving the capacity of high speed communication links employing MMFs. In this work, we study the effects of change in source wavelength on the excited single mode in the output MMF of an SMm structure. We show that the change in source wavelength deteriorates the single mode excitation of the output fiber. However, the same performance can be re-established by changing the length of the middle MMF. For small changes in the wavelength, we also give a simple formula to predict the required change in the length. © 2015 IEEE.

2015 21st National Conference on Communications, NCC 2015

Wavelength sensitivity of the excited single mode in the output Multimode fiber of an SMm structure

It is fairly well-known in circuit theory that the product of magnetic coupling coefficient and system quality factor is the single most important figure of merit (FOM) for optimizing the design of series-series-compensated resonant inductive coupling coils. Coils with high value of FOM can operate efficiently under misalignment conditions, such as poor coupling systems. This would be the case in transit systems with on-road/in-motion charging systems using inductive power transfer (IPT). Archimedean spiral coils are widely used for stationary charging of electric vehicles (EVs). This is due to ease of manufacturing, lower material cost, symmetric coupling profile, ease of experimental characterization, and very well-known magnetic characteristics. In this paper, a comprehensive analysis of Archimedean spiral coil structure has been presented, with the aim of establishing key design parameters, leading to high FOM. Knowing the key parameters in order to adjust the coupling coefficient and system quality factor gives a designer abundant options to design coils that can handle misalignment, and at the same time, minimize losses. For this purpose, 2D analysis of a range of coils with difference geometric parameters have been performed. Finite element analysis (FEA) has been used to establish key coil design parameters, in order to obtain a high value of FOM. Results of this design and analytical work will lead to efficient IPT coil design methodologies, which in turn will lead to considerable cost and energy savings. Due to their scalable and modular nature, this work is also applicable to any lumped system specifically utilizing Archimedean spiral coils. © 2015 IEEE.

IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society

Design considerations to obtain a high figure of merit in circular archimedean spiral coils for EV battery charging applications

Although coils for Inductive Power Transfer (IPT) works on the fundamental principle of Ampere's and Faraday's laws, on which conventional transformers work, there is difference in approach required for designing coils for IPT than designing a conventional transformer. Because of the complex design of some IPT coils and the increasing emphasis on the magnetic field strength of such systems, Finite Element Analysis (FEA) software is often used to model these systems. However modeling must be conducted very carefully in order to obtain the real behavior from the modeled coils. Aim of this paper is to study the modelling and calculation of key design parameters of IPT system through FEA analysis. A low power (capable of giving lOOW at its rated current) IPT setup has been built to verify the FEA analysis of IPT system. Key factors such modelling litz wire, importance of element size in Meshing, advantages and shortcoming of 2D modelling and 3D modelling as well as how to calculate the parameters of the coils has been discussed in this paper. In addition to that different electrical models used for representing IPT system has been studied and compared. © 2015 IEEE.

2015 IEEE Transportation Electrification Conference and Expo, ITEC 2015

Modelling and calculation of key design parameters for an inductive power transfer system using finite element analysis-A comprehensive discussion

Wireless charging of electric vehicles require a significant air gap between the primary and secondary winding of an inductive power transfer (IPT) system. Due to the existence of the air gap, power flow regulation to keep the output voltage constant becomes a non-trivial task. Hence, the bandwidth, phase margin, and gain margin of the voltage control loops should be appropriately designed, in order to guarantee a robust system. In this paper, a generalized small-signal modelling of series-series compensated (SS topology) IPT system using extended describing function concept has been presented. Using this small-signal model, a controller has been designed for fixed frequency and variable duty cycle, to control the output voltage. Since an asymmetrical clamped mode control (ACM) requires a lower switching frequency compared to the popular fixed frequency control strategies, viz. symmetrical clamed mode control (SCM) and asymmetrical duty cycle control (ADC), it has been used to control the output voltage. © 2015 IEEE.

Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Advanced controller design for a series-series compensated inductive power transfer charging infrastructure using asymmetrical clamped mode control

Low-loss high-performance systems with smaller footprints are highly regarded in the area of radio-frequency (RF) applications. In this paper, a multi-port single-pole six-throw (SP6T) based on RF MEMS ohmic switches design is proposed. The complete switch is designed with very small footprints of 1.2 mm$$^2$$2. Six ohmic/series microelectromechanical (MEMS) switches are designed to get high-isolation in microwave frequency range. The spring constant and actuation voltage required for the operation of the switches is computed using stress analysis module of finite element modeler. The robustness issue of RF MEMS switches can be increased by the proposed geometry. Based on the calculations and simulations, it can be seen that the switches can easily withstand the stress of $$\approx$$≈120 MPa. The simulated RF performance of SP6T switch exhibits isolation of 70–45 dB and insertion loss of 0.01 dB for DC to 6 GHz between input port and individual output port. The proposed SP6T switch require low operational voltage level of 12.5 V. © 2015, Springer-Verlag Berlin Heidelberg.

Microsystem Technologies

Compact low-loss high-performance single-pole six-throw RF MEMS switch design and modeling for DC to 6 GHz

Studies on IEEE 802.15.4 MAC in the current literature for anycast multi-hop networks do not capture a node's behaviour accurately. Due to the inaccurate modeling of state-wise behaviour of a node, the optimization of network parameters has not been efficient so far. In this work, we include the state-wise behaviour of a relay node into a 3D Markov model to more accurately investigate the protocol performance. Performance analysis of the proposed analytical model is evaluated for different variants of active state length, packet length and wake up rates considering reliability and delay as key performance metrics. Performance analysis shows that the model captures the behaviour of relay nodes most accurately. © 1997-2012 IEEE.

Fulltext

IEEE Communications Letters

Reliability and delay analysis of slotted anycast multi-hop wireless networks targeting dense traffic iot applications

MEMS technologies have enabled the development of various sensors including gas sensors in a miniaturized and cost effective way. Sensor systems are being developed using these sensor chips where chip packaging is still a major cost due to special requirements. This paper focuses on the packaging needs of a MEMS based gas sensor. These gas sensors have various applications in safety systems for fire and harmful gases detectors for automobiles, home, offices, factories, environment, etc. A low cost packaging solution for MEMS based gas sensors is elaborated which is suitable for the trace level detection of various lethal gases like H2S, PH3, CO, CO2, NH3 etc. To enable the vast and multiple applications of these gas sensors it is important to provide a low cost sensor system which is low power and can be operated on battery. Standard semiconductor device packages like TO headers are costly and not suitable for low cost devices. Proposed packaging scheme uses printed circuit board (PCB) as substrate material (FR4) where reliable low resistance (1–2 ohm) interconnects are provided by conducting epoxy. PCB based packages add very little extra power (3–5 mW) to the power required for micro-heater that heats gas sensor film up to 300 °C. Packaged gas sensors were tested for their reliability in two different conditions i.e. 1 h ON reliability test and repetitive ON/OFF (100 times) test. These packages have additional advantages of being more mechanically stable than wire bonded packages and easy processing in comparison to Transistor Outline (TO) headers. Infrared imaging of the packaged device in forced condition shows the stability of the package. © 2014, Springer-Verlag Berlin Heidelberg.

Low cost packaging for gas sensors

Realization of ubiquitous connectivity in remote health monitoring is a primary issue yet to be addressed. In this paper we propose a system architecture for IoT enabled remote health monitoring with smart transmission which can also aid in ubiquitous connectivity by targeting multiple on-chip radios (IEEE 802.15.4 and IEEE 802.11b in this case). We also optimize the area overhead by using modified IEEE 802.15.4-PHY architecture which uses Raised Cosine pulse shaping and the BER performance is also analyzed for same. The modified IEEE 802.15.4-PHY when used in multiple radio architecture along with IEEE 802.11b can result in significant area savings by multiplexing the commonly available functional units. The proposed architecture also aids for significant energy savings due to the presence of smart transmission technique. Performance of the proposed architecture is analyzed using energy consumption and BER as key performance metrics. The BER performance shows that the usage of raised cosine pulse shaping for IEEE 802.15.4-PHY achieves significant amount of area savings without losing any performance in BER. © 2014 IEEE.