DESIGN OF LOW COST AND INNOVATIVE DATA ACQUSITION IN SOIL MECHANICS TESTING USING OPEN SOURCE HARDWARE

Abstract

Sensors are increasingly in our lives, microprocessor technology is evolving and open source hardware is becoming widespread. Preparation of experimental setups using open-source hardware reduces research costs. Arduino is an open source development platform which is operated with an open source software. It consists Atmel AVR microcontroller, circuit elements for interfacing, a 5 volt regulated power and a 16MHz crystal oscillator. With 10 bit ADC, it can read 0-5V voltages in 1024 steps. There are at least six analog inputs and 13 digital input-output pins, which can meet the channel requirements of a soil mechanics laboratory. Together with the "do-it-yourself" civil movement, the use of these platforms by young engineers in particular will gain experience that can be helpful in different applications. This study explains design and development of a low cost and open source data acquisition system for soil mechanics laboratories. The main advantage of making laboratory scientific equipment by using open source hardware is that, shared design promotes a better design as the scientific community can contribute to its design. In modern geotechnical laboratories sensor readings are essential for many setups such as consolidation, uniaxial compression, triaxial compression and shear box tests. Moreover, some tests need temperature and humidity conditioning. In the setup, Arduino Uno model was used as a microcontroller. Sensors with a 5 volt supply can be connected directly, and a booster circuit is added to the circuit for sensors requiring a 10 volt supply. The data of sensors having 0-5 volt input signal can be directly digitized. For sensors with millivolt output such as load cells, a driver circuit is added. The code is written in the C ++ language. The acquired data are tabled on an Excel sheet and it is possible to process the data for specific needs. 

Keywords

• DAQ,open source hardware,soil mechanics laboratory

References

1. Arduino (2017). Arduino - Home, An Open-Source Electronics Prototyping Platform. https://www.arduino.cc/ Arsha Lekshmi, K.R., & Arnepalli, D.N. (2016). A methodology to determine water vapour diffusion characteristics of geomaterials. Indian Geotechnical Conference IGC2016 15-17 December 2016, IIT Madras, Chennai, India. ASTM D-2166 (2013). Standard Test Method for Unconfined Compression Strength of Cohesive Soil. ASTM International, West Conshohocken, PA D’Ausilio A. (2011). Arduino: A Low-cost Multipurpose Lab Equipment, Behav Res 44,305–313. Delage, P., Romero, E., & Tarantino, A. (2008). Recent developments in the techniques of controlling and measuring suction. In Proceedings of the 1st European Conference on Unsaturated soils: Advanced in Geo-Engineering, Durham, UK, 2–4 July 2008. Edited by D.G. Toll, C.E. Augarde, D. Gallipoli, and S.J. Wheeler. Taylor & Francis Group, London, UK. pp. 33–52. Dipova, N. (2016a). Infrared ısıtma ve nem yoğuşturmaya dayalı bir su içeriği cihazı geliştirilmesi, Zemin Mekaniği ve Geoteknik Mühendisliği 16. Ulusal Kongresi, Erzurum, 13-14 Ekim 2016, cilt.2, pp.1017-1024. Dipova, N. (2016b). Kızılötesi ve peltier teknolojili bir dijital hidrometre tasarımı ve geliştirilmesi, Zemin Mekaniği ve Geoteknik Mühendisliği 16. Ulusal Kongresi, Erzurum, 13-14 Ekim 2016, cilt.2, pp.997-1006. Dunnicliff, J. (1993). Geotechnical Instrumentation for Monitoring Field Performance. John Wiley and Sons, New York. Github Inc. (2017) An Arduino library to interface the Avia Semiconductor HX711 24-bit analog-to-digital converter (ADC) for weight scales. https://github.com/bogde/HX711. Han J.B., & Zhou, Z.F. (2013). Dynamics of soil water evaporation during soil drying: laboratory experiment and numerical analysis. Scientific World Journal, 2013, 240-280. Levine, S.S., & Prietula, M.J. (2014). Open Collaboration for Innovation: Principles and Performance. Organization Science, 25, 1414–1433. Pearce, J. (2012). The case for open source appropriate technology. Environment, Development and Sustainability, 14, 425–431. Plaisted, M., & Zornberg, J.G. (2013). Determination of the Swell-stress Curve of an Expansive Soil Using Centrifuge Technology. Proceedings of the 5th International Young Geotechnical Engineers’ Conference – 5th iYGEC 2013, 31 August-01 September, Paris, France, pp. 443-446. Raymond, E. S. (2001). The cathedral and the bazaar: Musings on Linux and Open Source by an accidental revolutionary. Beijing, O'Reilly. Vainino, N., & Vaden,T. (2007). Free software Philosophy and open Source, Handbook of reserch an Open Source Software, Information Science Reference, pp. 1-11