Sergio Llorente

Domestic Induction Appliances

In this paper several research topics pertaining to the design and modeling of domestic induction appliances are reviewed. Each topic is summarized, stressing its most significant advances and pointing to its future tendencies. A bibliographic review showing some of the published papers during the last years is included. The emphases and relative contributions of some of them are also discussed.

A comparative study of resonant inverter topologies used in induction cookers

In this paper, a comparison is performed between four inverter topologies commonly used in induction cookers. The considered topologies are the full-bridge inverter, the half-bridge inverter, and two single-switch inverters. All of them are designed for the same specifications and they are compared in aspects such as power device stresses, efficiency, frequency control and electromagnetic emissions.

The domestic induction heating appliance: An overview of recent research

In this paper several research topics pertaining to the design and modeling of domestic induction appliances are reviewed. Each topic is summarized, stressing its most significant advances and pointing to its future tendencies. A bibliographic review showing some of the published papers during the last years is included. The emphases and relative contributions of some of them are also discussed.

Human-Computer Interaction Based on Hand Gestures Using RGB-D Sensors

In this paper we present a new method for hand gesture recognition based on an RGB-D sensor. The proposed approach takes advantage of depth information to cope with the most common problems of traditional video-based hand segmentation methods: cluttered backgrounds and occlusions. The algorithm also uses colour and semantic information to accurately identify any number of hands present in the image. Ten different static hand gestures are recognised, including all different combinations of spread fingers. Additionally, movements of an open hand are followed and 6 dynamic gestures are identified. The main advantage of our approach is the freedom of the users hands to be at any position of the image without the need of wearing any specific clothing or additional devices. Besides, the whole method can be executed without any initial training or calibration. Experiments carried out with different users and in different environments prove the accuracy and robustness of the method which, additionally, can be run in real-time.

Adaptive Simmering Control for Domestic Induction Cookers

The goal of this paper is twofold. First, we aim at investigating the potentials of reset observers (ReOs) applied to process control. Second, we aim to overcome the existing performance limitations of the temperature control in domestic cookers. To this end, we present an adaptive simmering control for induction cookers, whose parameters are updated online, depending on the estimates provided by a multiple-model ReO (MMReO). This new observer results in extending the idea of multiple models to the state observer framework. The MMReO consists of a reinitialized ReO and of multiple fixed identification models. The resultant control scheme satisfies the user requirements such as quick heating up, accurate temperature control, and fast disturbance rejection, outperforming previous results. Moreover, the proposed control scheme reduces energy consumption, and consequently, it can increase the efficiency of the whole cooking process. Additionally, a fixed robust quantitative feedback theory (QFT)-based controller is designed, and it is also used for comparison purposes. Several verification tests are carried out in real induction hobs to emphasize the effectiveness of our proposal compared with the QFT-based controller.

Reset Adaptive Observer for a Class of Nonlinear Systems

This technical note proposes a novel kind of state estimator called reset adaptive observer (ReO). A ReO is an adaptive observer consisting of an integrator and a reset law that resets the output of the integrator depending on a predefined condition. The main contribution of this technical note is that the reset element theory is applied for the first time to the nonlinear adaptive observer framework. The introduction of the reset element in the adaptive law can decrease the overshooting and settling time of the estimation process without sacrificing the rising time. The stability and convergence LMI-based analysis of the proposed ReO is addressed and, additionally, an easily computable method to determine the L2 gain of the ReO dealing with noise-corrupted systems is presented.

Adaptive Observers Applied to Pan Temperature Control of Induction Hobs

In this paper, a pan temperature control of induction hobs is described. The aim is that the user may select the cooking temperature instead of the power for the cooker. Pan temperature has to be estimated from a thermal sensor placed under the ceramic glass. Heat transmission from the induction coil to the pan and from the pan to the thermal sensor is modeled using a state-space model. As induction heating is highly dependent on thermal and magnetic pan properties, two different adaptive schemes are proposed and compared. Both guarantee a proper closed loop behavior. The contribution of this paper is related with temperature adaptive observer for different pans. The resultant system is simple, user friendly, robust, and safe, and is used for automatic cooking.

Persistent coverage control with variable coverage action in multi-robot environment

In this paper we tackle the problem of persistent coverage, where a team of agents covers an area whose amount of coverage degrades with time. The task is never accomplished completely due to the coverage decay and the agents have to revisit the domain persistently. In this framework, our contribution is a novel approach which consists not only in developing efficient motion to perform the coverage, but also in covering the domain with a variable coverage action. The agents can adapt its coverage power to the coverage error of the actuator domain, being able to reduce the energy consumption and the coverage error. We propose a new controller for the coverage power and we demonstrate by means of simulations that it is more efficient and flexible than developing the coverage with constant power.

Electromagnetic induction of planar windings with cylindrical symmetry between two half-spaces

A closed-form solution is derived for the equivalent impedance of a planar winding with cylindrical symmetry placed between two half-spaces. This is basically the structure of a domestic induction heating appliance comprised of a planar winding, a metallic vessel, and a lossless magnetic substrate. The first matter addressed is the impedance of a sandwiched single-turn coil, obtained by using the vector potential Helmholtz equation solution, and the result is generalized to n-turn coils. The real part of this impedance represents power dissipated in the form of heat. The proposed model includes geometry dependence, frequency of excitation currents, and electromagnetic properties of both top and bottom media. Enhancement of power dissipation in the conducting media as a result of the inclusion of a magnetic substrate is also explored. Experimental results are presented in order to validate the theoretical model.

Induction Heating Appliance With a Mobile Double-Coil Inductor

An induction heating appliance designed to uniformly heat up metallic plates is studied in this work. It consists of one planar inductor with two concentric coils attached to a mechanism, which allows moving the inductor under the plate while heating. This system is a possible solution for the growing concept of flexible induction cooking hobs, improving their performance in flexibility and in thermal distribution in the pans. With different combinations of motion and the selective activation of the inductor coils, any pan can be uniformly heated regardless its size or position on the hob. In this paper we develop a thermal model to analyze the temperature distribution obtained in the pans for each diameter and strategy used. The model is solved using finite differences and it is validated with experimental measurements. From the calculations, the best strategy for each pan diameter is obtained.