Jose Farina

Optimization of an Industrial Sensor and Data Acquisition Laboratory Through Time Sharing and Remote Access

This paper presents an educational laboratory that has been implemented for the practical education in sensors, data acquisition, and basic control skills. The use of the laboratory has been optimized by the availability of a remote access infrastructure that allows the definition and booking of time slots related to the laboratory sites. Given the many kinds of existing sensors, conditioning circuits, and actuators, setting up an educational framework is a complex (and expensive) task, even if only the main design alternatives are taken into account. An additional and fundamental issue to be considered for the optimization of any educational resource or teaching/learning methodology is the possibility to adapt it to the capabilities of different profiles, i.e., students enrolled in different courses. The proposed solution has been designed to be used by both nonexperienced students, who act as plain users testing predefined experiments, and advanced ones, who can demonstrate the design skills they have learnt, by developing their own applications and conditioning circuits. Accordingly, the remote access infrastructure allows different kinds of users to be defined, whose capabilities, restrictions, and software requirements depend on their level of knowledge.

Industrial Laser Cladding Systems: FPGA-Based Adaptive Control

Laser cladding is a deposition process, depicted in Figure 1, which uses a laser beam to melt the surface of a metallic substrate and a substance added in the form of powder flow so that the two materials are fused by metallurgical bonding. Usually, laser cladding consists of a processing head, where the laser beam and powder flow are generated, that moves over the target part. The melted powder particles and a thin layer of the substrate form a clad, whose thickness and penetration depend on the control parameters of the process.

Distortion Mitigation in RF Power Amplifiers Through FPGA-Based Amplitude and Phase Predistortion

Strong requirements are currently imposed to limit the negative effects of distortion or bad synchronization between emitter and receiver in digital communication channels. Distortion is mainly caused by the output stage of the emitters power amplifier. It can be mitigated by applying to the input signals a correction, causing them a distortion contrary to that occurring in the amplifier (i.e., a predistortion). This paper presents a new method which combines amplitude and phase predistortion for digital video broadcasting-terrestrial (DVB-T) gap fillers (intermediate reemitters) in single frequency networks. These systems impose severe limitations to the time available for processing, which prevents the application of existing predistortion techniques. The method is based on a new high-frequency model of the output stage of the emitters power amplifier, from which the design of an efficient amplitude and phase predistorter is straightforward. An advantageous tradeoff between complexity and processing time is achieved by applying predistortion at intermediate frequency. In addition, the proposed solution is independent of the frequency of the output radio frequency signals. A predistorter has been implemented in a field-programmable gate array and applied to a real gap filler. Experimental results which show the significant improvement achieved in the quality of real DVB-T signals, as well as the low complexity and low processing delay associated to the proposed approach, are presented.

Field-Programmable System-on-Chip for Localization of UGVs in an Indoor iSpace

The ability to perform accurate localization is a fundamental requirement of the navigation systems intended to guide unmanned ground vehicles in a given environment. Currently, the use of vision-based systems is a very suitable alternative for some indoor applications. This paper presents a novel distributed FPGA-based embedded image processing system for accurate and fast simultaneous estimation of the position and orientation of remotely controlled vehicles in indoor spaces. It is based on a network of distributed image processing nodes, which minimize the amount of data to be transmitted through communication networks and hence allow dynamic response to be improved, providing a simple, flexible, low-cost, and very efficient solution. The proposed system works properly under variable or nonhomogeneous illumination conditions, which simplifies the deployment. Experimental results on a real scenario are presented and discussed. They demonstrate that the system clearly outperforms the existing solutions of similar complexity. Only much more complex and expensive systems achieve similar performance.

FPGA-based system for the education in data acquisition and signal generation

Signal generation, signal conditioning and data acquisition systems usually have fixed structures, whose functionality cannot be modified. In an educational context, students can only modify some of their functional parameters and check the effect of such changes on the generation and acquisition processes. This paper presents a reconfigurable signal generation, conditioning and acquisition system that, in addition to cover these basic educational tasks, allow students to test different structures and to choose the most suitable for a given application. It basically consists of a SCXI environment from national instruments and an FPGA development board, which adds reconfigurability capabilities to the system. An application example is discussed, in which functionality is reconfigured for reading an incremental encoder and generating a PWM signal.

Resolution in QCM Sensors for the Viscosity and Density of Liquids: Application to Lead Acid Batteries

In battery applications, particularly in automobiles, submarines and remote communications, the state of charge (SoC) is needed in order to manage batteries efficiently. The most widely used physical parameter for this is electrolyte density. However, there is greater dependency between electrolyte viscosity and SoC than that seen for density and SoC. This paper presents a Quartz Crystal Microbalance (QCM) sensor for electrolyte density-viscosity product measurements in lead acid batteries. The sensor is calibrated in H2SO4 solutions in the battery electrolyte range to obtain sensitivity, noise and resolution. Also, real-time tests of charge and discharge are conducted placing the quartz crystal inside the battery. At the same time, the present theoretical “resolution limit” to measure the square root of the density-viscosity product (ρη) of a liquid medium or best resolution achievable with a QCM oscillator is determined. Findings show that the resolution limit only depends on the characteristics of the liquid to be studied and not on frequency. The QCM resolution limit for ρη measurements worsens when the density-viscosity product of the liquid is increased, but it cannot be improved by elevating the work frequency.

Microcontroller-based monitoring of electrodes in arc furnaces for silicon production

Electrodes are fundamental elements in the operation of arc furnaces, to the extent that monitoring their state is a suitable way to check the operation of the furnace. In addition, the monitoring process allows the values of important parameters of the furnace to be determined. This paper presents the monitoring system that is currently being used at the silicon production facility of the company Ferroatlantica, in Spain. It is the result of the evolution from a previous, mainly analog, system to a microcontroller-based one. Experimental results that validate the operation of the new system are given.

On monitoring the state of electrodes in arc furnaces for silicon production

Electrodes are fundamental elements in the operation of arc furnaces, to the extent that monitoring their state is a very suitable way to check the operation of the furnace. In addition, in the cases where electrode breakages are relatively prone to occur, their early detection is very important to prevent damage to other parts of the furnace and to minimize production losses. This paper presents the monitoring system that is being used at the silicon production facility of the company Ferroatlantica, in Spain. Experimental results regarding the electrical characterization of the electrodes and proving the breakage detection capabilities of the developed system are given.

Analysis of two FPGA design methodologies applied to an image processing system

The continuous advancements in programmable device technologies enable the widespread use of FPGAs in an increasing number of industrial applications. The availability of powerful software design tools is a fundamental requirement to take advantage of the many advanced and specialized resources included in the latest devices. Although such tools exist, they are still far from guarantee first-time-optimized designs in many applications. This paper analyzes the application of two state-of-the-art FPGA design methodologies to an image processing system. The experimental results presented demonstrate that there is still much room left for experienced designers to enhance system performance.

A biosensor for detection of DNA sequences based on a 50MHz QCM electronic oscillator circuit

This work deals with the development of a high sensibility DNA biosensor based on a 50MHz Quartz Crystal Microbalance (QCM) Oscillator Electronic Circuit. The designed QCM oscillator sensor is able to detect the presence of complementary DNAs in a solution that match the sequence on a given strand in function of the changes in the output frequency of the oscillator. The design is adapted so that the Barkhausen condition is satisfied even when the quartz is immerged in liquid media. Also a comparative study of the developed 50MHz biosensor in front of a QCM oscillator with smaller frequency is carried out, with object of checking if the sensibility of the oscillator increases, allowing to detect smaller concentrations of the complementary DNA.