J. Suardíaz

Development of a sensor node for precision horticulture.

This paper presents the design of a new wireless sensor node (GAIA Soil-Mote) for precision horticulture applications which permits the use of precision agricultural instruments based on the SDI-12 standard. Wireless communication is achieved with a transceiver compliant with the IEEE 802.15.4 standard. The GAIA Soil-Mote software implementation is based on TinyOS. A two-phase methodology was devised to validate the design of this sensor node. The first phase consisted of laboratory validation of the proposed hardware and software solution, including a study on power consumption and autonomy. The second phase consisted of implementing a monitoring application in a real broccoli (Brassica oleracea L. var Marathon) crop in Campo de Cartagena in south-east Spain. In this way the sensor node was validated in real operating conditions. This type of application was chosen because there is a large potential market for it in the farming sector, especially for the development of precision agriculture applications.

A sensor system for detection of hull surface defects.

This paper presents a sensor system for detecting defects in ship hull surfaces. The sensor was developed to enable a robotic system to perform grit blasting operations on ship hulls. To achieve this, the proposed sensor system captures images with the help of a camera and processes them in real time using a new defect detection method based on thresholding techniques. What makes this method different is its efficiency in the automatic detection of defects from images recorded in variable lighting conditions. The sensor system was tested under real conditions at a Spanish shipyard, with excellent results.

Teleoperated Visual Inspection System for Hull Spot-Blasting

This paper presents a robotized teleoperated visual inspection system for spot-blasting applied to hull cleaning in ship maintenance tasks. It consists of a cleaning head, a robot body, a remote control unit, and a teleoperation platform connected to a computer vision system. This solution allows a reliable and cost effective operation for hull grit spot-blasting. A prototype of this robot has been developed and tested in the Spanish IZAR shipyards

Automatic generation of VHDL code from traditional ladder diagrams applying a model-driven engineering approach

Automation industry is experiencing a boom in the deployment of FPGA based controlling systems, which beat the run-time characteristics and behavior of microprocessors-based systems and which will bring new possibilities to the sector. Particularly, FPGAs are being progressively applied to develop PLCs. However, the end user, accustomed to traditional PLC programming environments, is reluctant to this new technology, which requires an additional effort for learning a new language and development environment. This paper presents a prototype tool that applies the relatively new Model-Driven Software Development approach to program these new devices using the classical ladder diagram notation. It also demonstrates its application in the classic star-delta starter for 3-phase motors.

Effect of the Output Impedance of Active Clamp Topology in Multiphase Converters

Passive current sharing in multiphase converters, where resistive losses are not dominant, is a quite complex goal. In this paper an averaged model of an active clamp converter was obtained. It has been checked that these topologies present high output impedance. This property is used like a lossless passive equalization. Simulated results of the average model accuracy and current sharing are presented.

Design and Implementation of a Wireless Sensor Network for Precision Horticulture

A prototype wireless sensor network for measuring soil and environmental characteristics was developed and evaluated for purposes of scheduling irrigation on field vegetable farms. The system consists of a central base station connected to multiple sensor nodes installed in the field and distributed over several crops. The sensor nodes consist of specially designed hardware which transmits data to a base station inside the farm offices. The relatively low cost of the system (USD 6000 for a 20-sensor node system) allows for installation of a dense sensor population that can adequately represent inherent soil characteristics such us temperature, volumetric moisture content, salinity and so on. Additional sensors can be used to measure environmental variables and the quality of the water used to irrigate the crops. This paper describes our experience during the design and implementation of the wireless sensor network and its components in a field crop of Broccoli (Brassica oleracea L. var Marathon) in the semiarid region of Campo de Cartagena in Southern Spain. It presents the topology of the network, which was deployed using three types of sensor nodes (Soil-Mote, Environmental-Mote and Water-Mote).

Defect Detection in Textures through the Use of Entropy as a Means for Automatically Selecting the Wavelet Decomposition Level

This paper presents a robust method for defect detection in textures, entropy-based automatic selection of the wavelet decomposition level (EADL), based on a wavelet reconstruction scheme, for detecting defects in a wide variety of structural and statistical textures. Two main features are presented. One of the new features is an original use of the normalized absolute function value (NABS) calculated from the wavelet coefficients derived at various different decomposition levels in order to identify textures where the defect can be isolated by eliminating the texture pattern in the first decomposition level. The second is the use of Shannon’s entropy, calculated over detail subimages, for automatic selection of the band for image reconstruction, which, unlike other techniques, such as those based on the co-occurrence matrix or on energy calculation, provides a lower decomposition level, thus avoiding excessive degradation of the image, allowing a more accurate defect segmentation. A metric analysis of the results of the proposed method with nine different thresholding algorithms determined that selecting the appropriate thresholding method is important to achieve optimum performance in defect detection. As a consequence, several different thresholding algorithms depending on the type of texture are proposed.

Development of a mote for horticulture based on the SDI-12 standard

GAIA is a new kind of mote specially designed for horticultural farming. It is based on the SDI-12 standard, which allows the connection of the mote to a large number of agricultural instrumentation. The mote is built around a 16-bit Msp430f1611 micro-controller operating at a clock frequency of 32 MHz and accessing up to 10 KB of on-chip RAM. Wireless communication is achieved by the Chipcon CC2420 radio, which operates in the 2.4 GHz ISM band, and is compliant with the IEEE 802.15.4 standard. This mote was developed to monitor broccoli crops situated on a farm in South-East Spain. This paper shows the main requirements from which the design was developed. Its associated hardware architecture and software platform are presented. Finally, some test results obtained from the final system are presented.

On-line quality control assessment of the production process of preserved orange segments

This paper describes an automated visual inspection (AVI) system for quality control of preserved orange segments, which can be widely applied to production processes of preserved fruits and vegetables. Main constraints concerning these kinds of inspection applications are addressed: the need of on-line operation together with a strong requirement of economic profitability. The strong commitment of above circumstances has forced the development of a flexible and low cost AVI architecture. The data volume to be processed forced up the development of sophisticated control architecture for high-speed machine vision applications. Special effort has been put in the design of the defect detection algorithms to reach two main objectives: accurate feature extraction and on-line capabilities, both considering robustness and low processing time. These goals have been achieved combining a local analysis together with data interpretation based on syntactical analysis, which has allowed avoiding morphological analysis. An on-line implementation to inspect up to ten orange segments per second is reported.

Adaptive image acquisition and pre-processing in triggered vision systems

Triggered vision systems show several difficulties mainly concerning adaptation to varying lighting conditions. This paper presents a novel technique that makes possible that asynchronous triggered vision systems perform in outdoor environments. We propose to use an adaptive PID controller to adjust the exposition time of a LinLog sensor, together with an adaptive background estimation algorithm followed by an image restoration.