EE Lab 8
EE Lab 8 EE 1106 - 001
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This 7 page Bundle was uploaded by Kumar Jyoti on Sunday January 3, 2016. The Bundle belongs to EE 1106 - 001 at University of Texas at Arlington taught by Gregory K Turner in Fall 2015. Since its upload, it has received 58 views. For similar materials see ELECTRICAL ENGINEERING FRESHMAN PRACTICUM in Electrical Engineering at University of Texas at Arlington.
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Date Created: 01/03/16
EE1106 – Introduction to Electrical Engineering Practicum Lab Report Grading Rubric (To be attached as a coversheet to EVERY report) FORMATTING (see comments in graded report for more explanation): Formatting Evaluation Key (Lab 1, 2, 3, 4): 0 = Absent 1 = Extremely Lacking 2 = Poor 3 = Fair 4 = Good 5 = Excellent Formatting Evaluation Key (Lab 5 and all succeeding labs): 0 = Extremely Lacking 1 = Poor 2 = Fair 3 = Good 4 = Excellent 5 = Perfect Primary Structure: _____ Proper margins/spacing is used throughout the report (IEEE format) _____ Proper formatting of section titles and subtitles (IEEE format) _____ Proper font and font size (IEEE format) _____ Overall consistency of formatting throughout the report Figures/Tables: _____ Figures/tables are appropriately named and numbered (IEEE format) _____ Figures/tables are appropriately sized and spaced _____ Screenshots are neatly cropped and clear Spelling, Grammar, and Writing Style: _____ Spelling _____ Passive voice is used throughout the ENTIRE report _____ Sentence Structure _____ Paragraph Structure (IEEE format) _____ References (IEEE Format) CONTENT (see comments in graded report for more explanation): Content Evaluation Key: 0 = Absent 1 = Extremely Lacking 1 2 = Poor 3 = Fair 4 = Good 5 = Excellent _____ Abstract provides endtoend coverage of the objectives and purpose of the lab experiment _____ Introduction demonstrates a working understanding of major theoretical concepts required for the experiment _____ Procedure is sufficiently detailed and clearly describes all steps taken during the lab experiment _____ Results are sufficiently detailed and data is neatly organized _____ Discussion is a thoughtful analysis of all experimental results and data _____ Discussion demonstrates a working understanding of the purpose of the experiment performed _____ Conclusion sums up the overall accomplishments of the experiment _____ Conclusion sums up the benefits (to the student) of performing the experiment 2 Lab Report 8 Pressure Sensing Kumar Aman Jyoti Electrical Engineering University of Texas at Arlington Arlington, Texas Kumar.firstname.lastname@example.org as a scuba diver or submarine dives deeper into the ocean, the pressure increases. Abstract: This paper is about learning how to measure pressure A pressure measurement can be described as either static or exerted by us on a weight and gaining familiarity with the dynamic. The pressure in cases where no motion is occurring Wheatstone bridge, piezo resistive elements and their is referred to as static pressure. Examples of static pressure application for pressure sensing. We will use the concepts of include the pressure of the air inside a balloon or water inside Wheatstone bridge, Resistance Change due to stress on the piezo a basin. Often times, the motion of a fluid changes the force resistive element and Simulation of Circuit implementation on applied to its surroundings. Such a pressure measurement is breadboard. I. INTRODUCTION known as dynamic pressure measurement. For example, the pressure inside a balloon or at the bottom of a water basin The purpose of this lab is to gain familiarity with the would change as air is let out of the balloon or as water is Wheatstone bridge, piezo resistive elements and their application for pressure sensing. The experiments performed poured out of the basin. Head pressure (or pressure head) in this lab involves concepts of Wheatstone bridge, measures the static pressure of a liquid in a tank or a pipe. Resistance change due to stress on the piezo resistive element Head pressure, P, is a function solely on the height of the and simulation of circuit implementation on breadboard. liquid, h, and weight density, w, of the liquid being measured Pressure is defined as force per unit area that a fluid exerts on as shown in Figure 1 below. its surroundings. For example, pressure, P, is a function of force, F, and area, A. P = F/A A container full of gas contains innumerable atoms and molecules that are constantly bouncing of its walls. The pressure would be the average force of these atoms and molecules on its walls per unit of area of the container. Moreover, pressure does not have to be measured along the wall of a container but rather can be measured as the force per unit area along any plane. Air pressure, for example, is a function of the weight of the air pushing down on Earth. Thus, as the altitude increases, pressure decreases. Similarly, 3 Figure 1. Head Pressure Measurement Fig 3: Breadboard Circuit We then placed the pressure sensor in place of Rx and used Because of the great variety of conditions, ranges, and materials for which pressure must be measured, there are the 5V power supply from your My DAQ as V input. The many different types of pressure sensor designs. Often we next major procedure was to write the VI to acquire the measure pressure by converting it to some intermediate form, voltage Vb. The VI is shown below. such as displacement, which we can then measure with a sensor. Different methods are available for measuring pressure depending on whether the pressure being measured is greater or less than atmospheric pressure. Of all the pressure sensors, Wheatstone bridge (strain based) sensors are the most common, offering solutions that meet varying accuracy, size, ruggedness, and cost constraints. II. PROCEDURE We started with building the network N1 shown in the figure below on our breadboard. The breadboard circuit is also Fig 3: The VI shown in Figure 2. After this we placed a DAQ assistant with as stop control, analog Input Voltage, Voltage range from 10V to 10V sampling on demand and then connected to Vb. Now place an Indicator of type DBL and connect to your DAQ assistant data output. We then performed our conversion from voltage Vb using the calculation in Part A and the voltage reference hence using it as a control input. Vb is the data from DAQ Assistant data output. Now place a meter to represent PSI to the output of your conversion. We then measured Vb for the following similar to Part A which is No load on pressure sensor, secondly with 100g, 200g and 300g load on sensor. Finally we recorded the values as given in the Tables below. Fig 2 : Network N1 4 Breadboard Circuit Voltage Vb Resistanc Weight Lbs/Sqln (PSI) Vb Voltage e 120K 0 0 2.43415 90K 100 1.9963 2.11399 Fig 4: Circuit with Weight on it. 39K 200 3.9936 1.63194 Once you have chosen a sensor, you must connect it to your DAQ system. As with any other bridgebased sensor, there 28K 300 5.9851 0.934386 are several signal conditioning considerations. Strain based sensors typically provide small signal levels. It is therefore important to have accurate instrumentation to amplify the signal before it is digitized by a DAQ device. Additionally, all bridgebased sensors require voltage excitation to return a voltage representing strain. This voltage source should be constant and at a level recommended by the sensor manufacturer. Excitation and amplification are necessary to accurately measure the electrical response of a sensor. IV. DISCUSSION While performing procedures for experiments for calculating III. GRAPHS AND TABLES pressure we learned different types of methods and concepts. These experiments involve the theory and applications of Wheatstone,Bridge, piezoresistive elements and Table 1: Simulation Voltage Vb their application for pressure sensing. Simulation Voltage Vb Wheatstone bridge or strainbased transducers are a common way of measuring displacement. Sensors using this type of design meet a variety of requirements such as accuracy, size, Resistance Weight Lbs/Sqln Vb Voltage cost, and ruggedness. Bridge sensors are used for high and (PSI) lowpressure applications, and can measure absolute, gauge, or differential pressure. Bridgebased sensors use a strain 120K 0 0 1.944V gage to detect the deformity of a diaphragm subjected to the applied pressure. 90K 100 1.9963 1.786V We can use any value of resistors if a different piezoresistive element given to me. 39K 200 3.9936 1.111V When all the resistors have the same value then the voltage will be Zero Volt. 28K 300 5.9851 755.801mV Table 2: Breadboard Circuit Vb 5 are it can be measured in different fields like the one we did in this Lab. V. CONCLUSION After doing this lab we were able to learn about some concepts like Wheatstone bridge, Resistance change due to stress on the piezo resistive element and simulation of circuit V. REFERENCES implementation on breadboard. We also learned how to measure pressure using these very useful concepts mentioned  Lab 8 handout from Lab wiki page  www.ni.com/PressureMeasurements/ above. Apart from that we learned what pressure is and what  Wikipedia Pressure 6
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