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Roger C. Ellis 801-706-3706 ECE 5320 - Mechatronics Assignment #1.

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Presentation on theme: "Roger C. Ellis 801-706-3706 ECE 5320 - Mechatronics Assignment #1."— Presentation transcript:

1 Roger C. Ellis 801-706-3706 ECE 5320 - Mechatronics Assignment #1

2  Reference list  Major applications  Working principle  Example in field  Specifications  Limitations  Where to find

3  Campbell Scientific Inc.  Durham Geo Slope Indicator  Geokon  Gauge Technique  Roctest

4  piezo-vw.html piezo-vw.html  php/PressureSensors php/PressureSensors  http://www.gage- intro.html http://www.gage- intro.html  p?id=705 p?id=705

5  Monitoring water pressure in and out of a tank.  Pore pressure monitoring on land fills and tailing dams.  Structural monitoring of strain and/or load.  Any other application that requires a monitoring of pressure, strain, load or water depth.

6 Figure from:

7  Bore holes are drilled into sensor to allow pressure into main chamber. Usually passing through a filter in order to rid the system of particles.  Fluids or gases then push on the diaphram  Pressures on the diaphragm cause changes on the tension & frequency of the wire.  Wire is excited by the electromagnetic coils  Changes in these parameters are then transmitted through the coils to a read out device or a datalogger to save measurement details

8  Pressure in fluid tank A vibrating wire piezometer is inserted into a tank. Calibration is typically not required depending on model Once inserted into tank a measurement is taken. Giving the user the pressure at the bottom of the tank. Any changes in fluid level will result in a new measurement shown by the sensor.

9 Figure from: artinez/vibrating-wire-strain-gage.jpg

10  Connect across the axis of interest Usually involves soldering of the sensor to the structure  Strains to the load or structure will cause the resistive element inside the sensor to expand or contract.  Measuring the total resistance of the element will tell the amount of strain the structure or load.

11  Strain Solder sensor to desired axis of measurement on bridge Connect sensor to a voltage source as well as a data logger to keep track of the measurements and data When load is under stress and experiences a strain the sensor will interpret that with a change in resistance and thus a change in measurement will occur.

12  Pressure: different models range from 0 – 1000+ psi.  Pressure accuracy: ±0.1% of full scale output  Temperature: Operating range -40 o C to 230 o C  Extremes not available in a single model  Resolution: 0.025%FS  Filter: 50-micron sintered stainless steel Some models also have ceramic filters  Mass: anywhere from.10kg to 1.5kg

13  Diaphragm displacement: <.001 cm 3  Linearity: < 0.5% FS  Sensitivity: 1*10^5 Mpa  Thermal Drift: < 0.1% F.S. / °C  Input signal, sinusoidal: 150 to 170 mV rms  Output signal, sinusoidal: 10 to 30 mV rms

14  What type of material is your vibrating wire senor going to be located in?  Some environmental factors require the that sensor have a non-corrosive exterior  Higher pressure applications require a stronger exterior  Sensor data must be transmitted to a source via a cable. Choosing the cable sheath is also important, different applications call for different requirements.

15  How are you going to extract the data given by the sensor?  Handheld devices are available to read out the current data  Data loggers are mini computers that are programmable and can be used to read, process, and save data from the vibrating wire sensors. These are typically used if you want to monitor a system for an extended period of time.

16  High rate of change in pressures (depending on make and model)  Casing – different applications require different housing  Various models don’t come with a thermistor for temperature acquisition  Cheaper models cover smaller pressure spectrum  7.5 MPa is highest pressure I’ve found  Thermal operating range – higher temps usually require more expensive models

17  Geokon: $395 - ~$1300  Gauge Technique  Roctest  Slope Indicator (VWP series): $350

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