Browsing by Subject "Wireless sensing"

Now showing 1 - 3 of 3

Open Access
Innovative modular and arrayed coil systems for ultrahigh efficiency in inductive heating and automated metal detection
(2016-12) Kılıç, Veli Tayfun
Induction systems have become increasingly more important and popular in our modern world and their application areas have widely expanded because of their high levels of safety and controllability. Today one important application of these induction systems is the inductive heating, which now finds use not only in conventional applications of point-source heating but also in new areas including all-surface heating with some degree of exibility in localization. The efficiency of such emerging systems, especially in planar structures across an entire surface, however, has thus far been limited compared to conventional inductive heating. In this thesis, to address these problems, we show a new class of strongly coupled planar coils that enhance magnetic coupling in square lattice stacking by design and with phase difference application in operation. These coils can be tiled in two-dimensional arrays in a modular fashion or to cover an arbitrarily large continuous surface. In a proof-of-concept realization, we experimentally demonstrated that these proposed outer squircle-inner circular coils outperform the conventional coils of circular shape. Using square-arrayed coil architecture, here we also present all-surface induction systems achieving uniform and enhanced heating speed for all loading positions no matter what the misalignment of the heated vessel with respect to the coils is. In addition, to solve the problems of automatically detecting metals over the whole surface together with determining their exact positions, we introduce a new method that relies on simultaneous wireless measurement and tracking of inductance-resistance of the coils at multiple frequencies to identify those coupled with the metal targets to be detected in the system. While pinpointing the location of the targeted metals, the proposed technique also identifies their material types. For future ubiquitous all-surface systems, this approach allows for automated sensing of metal vessels and powering the loaded coils for the highest possible performance independent of the specific location of each vessel with respect to coils. These findings indicate that the proposed innovative modular and arrayed coils enable, for the first time, full degree of exibility in localized inductive heating with space-invariance in all-surface heating.
Open Access
Wireless metal detection and surface coverage sensing for all-surface induction heating
(MDPI AG, 2016) Kılıç, Veli Tyfun; Ünal, Emre; Demir, Hilmi Volkan
All-surface induction heating systems, typically comprising small-area coils, face a major challenge in detecting the presence of a metallic vessel and identifying its partial surface coverage over the coils to determine which of the coils to power up. The difficulty arises due to the fact that the user can heat vessels made of a wide variety of metals (and their alloys). To address this problem, we propose and demonstrate a new wireless detection methodology that allows for detecting the presence of metallic vessels together with uniquely sensing their surface coverages while also identifying their effective material type in all-surface induction heating systems. The proposed method is based on telemetrically measuring simultaneously inductance and resistance of the induction coil coupled with the vessel in the heating system. Here, variations in the inductance and resistance values for an all-surface heating coil loaded by vessels (made of stainless steel and aluminum) at different positions were systematically investigated at different frequencies. Results show that, independent of the metal material type, unique identification of the surface coverage is possible at all freqeuncies. Additionally, using the magnitude and phase information extracted from the coupled coil impedance, unique identification of the vessel effective material is also achievable, this time independent of its surface coverage.
Embargo
Wireless RF sensing in ionic aqueous environment: modeling, design and validation
(2024-07) Gholami, Sobhan
In light of the growing crisis of climate change, there is an urgent call to preserve the available limited resources like water. One of the sources of water use in everyday life is for hygiene, which has not received much attention for technological advancements from electrical engineering point of view to date. Water use in bathrooms is not regulated or controlled and the amount of water used is completely dependent on the bathroom user. A wireless sensor designed to detect the amount and type of excreta in a toilet bowl would be a game changer facilitating ways to regulate or adjust the water consumption for automatic cleaning. The design and operation of such a sensor are, however, extremely challenging due to the complicated environment in a bathroom. A proper sensor for this task must satisfy many requirements to be finally worthy of being installed in bathrooms. While providing privacy for users, the sensor must operate wirelessly from the exterior and be sensitive only to the inside of the bowl. This requirement hides the sensor from users and cleaners and preserves it from direct contact with the waste water or excreta. Moreover, the sensor must be conformable to take the shape of most of the currently available toilet setups. The potentially low cost and low noise performance of microwave sensors make them possibly an excellent candidate for the task. Unfortunately, a wireless sensing technology that meets all these requirements does not currently exist. In this thesis, to meet this technological gap, a functionally novel near-field RF sensor operating at 680-700 MHz with a single port which requires rather cheap and easy-to-manufacture circuitry is proposed and demonstrated employing a unique combination of spectral response and time-transient behaviour together for the first time. The proposed sensor is designed to be specifically coupled in the near field to the porcelain wall of the toilet bowl and water inside it which makes it impervious to the surrounding environment. It is installed on the three-dimensional surface of the outer wall of the U-pipe at the bottom of the bowl and performs sensing according to the changes occurring inside the U-pipe. The developed sensor is capable of sensing the addition of ionic content to the water inside the toilet, the same as the case when urine is injected into the bowl. Using artificial urine, the sensor is shown to detect ionic concentrations (down to 31 mM) in water which perfectly suits the application. Moreover, the addition of solid objects into the aqueous medium is demonstrated to be sensed using the time modulation of the surface of the water. Such characteristic modulations created on the water surface (ripples) are detected by the sensor in terms of time-transient shifts in resonance frequency. Deriving the Fourier content of the derivative of the frequency shift read-out in time produces valuable information for specifically differentiating between solid insertion and liquid addition into the bowl. In fact, section-by-section Fourier transforms of the frequency shift derivative while recording the maximum magnitude helps constructing a decision-making graph. This contains the useful information in the Fourier domain to determine whether solids or liquids were inserted in the medium by simple thresholding. Such extracted information plays a key role in choosing suitable washing mechanism to save water. The findings of this thesis indicate that this developed technology of wireless RF sensing in an aqueous environment holds great promise for smart bathroom and green cleaning applications.