Low-cost Digital Devices Research Articles

Digitalisation for SME Manufacturers: A Framework and a Low-Cost Approach

This paper is concerned with examining and prioritising the specific requirements SME manufacturers have for digital solutions and approaches for developing such solutions based on low-cost technologies and processes. In particular, this paper proposes an end-to-end conceptual framework for addressing the key barriers and opportunities for digitalisation in SME manufacturers. It then shows how this framework has been used to guide the developments in the Digital Manufacturing on a Shoestring programme - an ongoing UK-based research programme developing low-cost digital solutions for SMEs. The framework is intended to provide a reference point in the areas of low-cost digital and automated solutions - which has had surprisingly limited focus to date and also provide support for academic developments targeted at supporting the digital needs of manufacturing SMEs and suggests an application opportunity for modular and reconfigurable systems architectures. The so-called digital Shoestring approach exploits the fact that many low-cost digital devices and software being developed in the non-industrial domain (e.g. sensors, wifi cameras, game controllers) may well have direct industrial applicability. The novelty of this work lies in the recognition that a low-cost pathway to helping SME manufacturers address digitalisation may address an outstanding industrial need and that the use of non-industrial digital technologies and methods may provide advantages.

The Harmonic Order Tracking Analysis (HOTA) for the Diagnosis of Induction Generators Working Under Steady State Regime

Improved fault diagnostic techniques in induction generators is a field of growing interest given the negative impact *that unexpected breakdowns have on energy production and on the electrical system. New diagnostic techniques based on induction generator currents monitoring have recently been developed, but their use is still irrelevant despite the advantages that presents to detect electrical faults in the generator. This situation is due to the needs of high computing power and memory resources which are not available in embedded devices for on-line monitoring, also, to the use of signal processing techniques that generate volumes of data difficult to transfer to control centres, where they could be processed. This paper proposes the use of a recent methodology known as the harmonic order tracking analysis (HOTA) that solve these problems to for the diagnosis of induction generators. This approach can be implemented in low cost digital devices; the resultant patterns are very simple and easily interpretable, even by nonqualified personnel. Moreover, these patterns are characterized by a very low number of parameters, which make easy their transmission to remote control centres. In this paper the practical application of this approach is proposed using a laboratory test bed.

Colorimetric analysis of soils using digital cameras

Color is an important physical property in the diagnosis of soils and the description of soil profiles. Quantitative data from spectrophotometers and colorimeters have been used in soil studies for this purpose, but Munsell color description remains the main method of soil color evaluation. Low cost digital devices (cameras) could largely replace the semi-quantitative assessment of color yielded by Munsell charts, so long as they can be colorimetrically characterised to yield accurate and reproducible data. In this study, we explore the feasibility of using a digital camera to derive colorimetrically accurate images and data of 136 soil samples, using soil chart for calibration. Accurate color characterization can be achieved (ΔEab* color errors of <3) for 84% of studied soil samples, highlighting the merit of this rapid and low cost approach for soil color evaluation.

An Hybrid Digital-Analog Sliding Mode Controller for Photovoltaic Applications

Sliding mode is a control technique that is widely employed in switching converter applications. Such a nonlinear control technique, which is commonly implemented by means of analog circuitry only, forces the switches commutations by comparing a reference signal with a combination of signals acquired on the converter itself. In this way, the control action and the switching modulation are integrated in a single functional block. In this paper the implementation of the sliding mode controller in a low cost digital device is discussed. The proposed approach profits from features offered by some digital devices, e.g., the dsPic33FJ16GS502 family from Microchip Technology Inc., in order to make the implementation simple. In the paper, the aspects related to the accuracy of the comparison between the signals required by the sliding mode controller are discussed. Moreover, the elaboration time needed to calculate the signals that drive the converter's switching devices is the subject of an in-depth analysis. The techniques proposed in the paper have been validated by means of simulations and through experimental results performed on a switching dc/dc converter for photovoltaic applications.

Colorimetric detection of formaldehyde: A sensor for air quality measurements and a pollution-warning kit for homes

The development of new chemical sensors for the detection of formaldehyde, a ubiquitous and carcinogenic indoor air pollutant is described. These sensors are based on the use of nanoporous matrices acting as sponge to trap the targeted pollutant and doped with Fluoral-P for a selective detection of formaldehyde. A colorimetric pollution-warning kit, which displays a progressive color change visible by eyes, is provided for homes. For a quantitative and precise measurement of the air quality in public area, a lowcost digital device is proposed.

Frequency Diagnostic Universal Fault Protection for Current Fed Parallel Resonant Electronic Ballast

Current fed parallel resonant electronic ballast (PREB) dominates the applications for the T8 fluorescent lamp in North America for its advantage of low cost, flexibility and high reliability. At fault condition, a PREB generates much heat externally, and it is difficult to provide fault protection with traditional approaches. In this paper, a digital solution is presented to detect universal fault condition in PREB without sacrificing its other advantages. Operational principal of PREB is explored to show that the load impedance disturbance in PREB leads to frequency perturbation of the inverter, which can be detected with a very simple and low cost digital device for fault detection. Experiments show that this frequency diagnostic provides very sensitive and reliable fault detection for PREB. With both end-of-life lamp and anti-arcing protections implemented with one algorithm, this technology provides a superior fault protection to one of the most widely used ballast topologies and extends the potential applications of PREB in modern lighting industry

Design and Calibration of an Objective Flickermeter

Measurement of light flicker according to current standard EN ISO 61000-4-15 is performed through measurement of voltage variations filtered by a model of a 60 W/230 V incandescent lamp. Hence, differences in current illumination systems technology can determine discrepancies between light flicker measurements performed under the same voltage flicker. In the paper, a method to measure light flicker with a low cost digital device, based on light intensity measurements, is proposed, thus including the lamp itself in the measurement process. In this way an objective measurement of light flicker is obtained. The metrological characterization of the device has been implemented by means of an automatic testing station which includes a standard IEC flickermeter (Norma D6000) as reference instrument. Thanks to its portability, the instrument can be used to measure light flicker no matter the illumination system used, over a wide range of environments spanning from home/office to industrial locations, and including the environmental condition (i.e., ambient light and reflection by walls and objects) in the measurement process