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Data Acquisition Methods & Systems: A Comprehensive Overview

Explore experimental, descriptive, relational, and difference research methods. Learn about distance measuring devices, best practices, signal conditioning, data acquisition systems, resolution, and software. Understand the factors influencing the choice of methods and devices. Discover how to design a data acquisition system, consider references, and delve into quantitative and qualitative analysis.

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Data Acquisition Methods & Systems: A Comprehensive Overview

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  1. Data Acquisition and Analysis HU164_Lecture 5

  2. RESEARCH METHODS: • Experimental research • Descriptive • Relational • Difference All Require Data HU164_Lec4_Data Acquistion

  3. Distance Measuring Methods/devices • Pacing • Odometer • Chaining • Stadia • Electronic Distance Measuring (EDM) • Global Positioning System (GPS) HU164_Lec4_Data Acquistion

  4. The “Best” Method The best distance measuring method/device to use is influenced by many factors. • Environment • Use of the data • Equipment available • Expertise of individuals • Personal preference • Topography • Client specifications • Regulations • Standard practice The most important factor is the intended use of the data. HU164_Lec4_Data Acquistion

  5. Output, Vo (V) Force, F Slope = 5 V/kN Output, Vo Load Cell Input, Fi (kN) Block Diagram: Input, F (kN) Output, Vo (V) K Sensitivity, K = 5 V/kN HU164_Lec4_Data Acquistion

  6. Resolution This is defined as the smallest input increment change that gives some small but definite numerical change in the output. HU164_Lec4_Data Acquistion

  7. Data Acquisition System • A data acquisition system consists of many components that are integrated to: • Sensephysical variables (use of transducers) • Condition the electrical signal to make it readable by an A/D board Analogue-to-Digital converter HU164_Lec4_Data Acquistion

  8. DAS Functions • Convert the signal into a digital format acceptable by a computer • Process, • Analyze, • Store, and • Display the acquired data with the help of software HU164_Lec4_Data Acquistion

  9. Typical Block Diagram for DAS HU164_Lec4_Data Acquistion

  10. Examples Temperature Pressure Light Force Displacement Level Electric signals Transducers Sense physical phenomena and translate it into electric signals. HU164_Lec4_Data Acquistion

  11. Signal Conditioning Electrical signals are conditioned so they can be used by an analog input board. The following features may be available: • Amplification - Isolation • Filtering - Linearization HU164_Lec4_Data Acquistion

  12. 4 Samples/cycle 16 Samples/cycle Analog Input 8 Samples/cycle Analog to Digital (A/D) Converter • Input signal • Sampling rate HU164_Lec4_Data Acquistion

  13. A/D Converter: Resolution HU164_Lec4_Data Acquistion

  14. Data Acquisition Software • It can be the most critical factor in obtaining reliable, high performance operation. • Transforms the PC and DAQ hardware into a complete DAQ, analysis, and display system. • Different alternatives: • Programmable software. • Data acquisition software packages. HU164_Lec4_Data Acquistion

  15. Designing a DAS: Factors to Consider • Fixed or a mobile application • Type of input/output signal: digital or analog • Frequency of input signal • Resolution, range, and gain • Continuous operation • Compatibility between hardware and software. Are the drivers available • Overall price. HU164_Lec4_Data Acquistion

  16. References • Measurement and Data Analysis for Engineering and Science (2nd Edition) by Patrick F. Dunn, CRC Press, 2010 • A Practical Guide to Scientific Data Analysis, David J. Livingstone, Wiley, 2009 HU164_Lec4_Data Acquistion

  17. All analysis involves theory • Because your prior ideas guides your eyes • Because “pure observations”, neutral and objective, not guided by your “prejustice”, is unlikely HU164_Lec4_Data Acquistion

  18. Quantitative inquiry • Theory guides the development of instruments • If not: theory is still embedded in the instrument • An analysis of the instruments might reveal the underlying theory • Knowledge of the instrument’s theory-base is necessary to interpret findings in adequate terms HU164_Lec4_Data Acquistion

  19. Data Analysis HU164_Lec4_Data Acquistion

  20. Qualitative inquiry • Theory guides • the foci for the study • the research questions • the collection of data • the analysis of data HU164_Lec4_Data Acquistion

  21. HU164_Lec4_Data Acquistion

  22. Quiz 1 12/11/2012 Answer one question only • State three steps to critically evaluate information and discuss one of them. • Differentiate between hypothesis, assumption and theory, providing example for each. HU164_Lec4_Data Acquistion

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