OREGON STATE UNIVERSITY
ME 451 - INTRODUCTION TO INSTRUMENTATION AND MEASUREMENT SYSTEMS
Lab Report Guidelines – Accelerometer Lab – Fall 2008
Due: Tuesday, October 21, 2008 (bring to your lab section)
Write a report describing the accelerometer experiment according to the following guidelines. Use headings
and subheadings exactly as shown, and pay careful attention to the content of each section. Use
recommendations in “A Guide to Writing as an Engineer” where appropriate.
I. INTRODUCTION
Briefly describe the purpose and scope of the experiment.
II. METHODS
Provide enough detail (and no more) to allow an individual with your background to repeat the experiment.
a.
Equipment
Illustrate the hardware set-up used for the experiment. Create a table that includes the
manufacturers and model numbers of the equipment used.
b. Program
Write pseudo-code describing the control structure of your LabVIEW program. Look here -http://en.wikipedia.org/wiki/Pseudocode -- for a brief description of pseudo-code. Create figures
that illustrate the Block Diagram and Front Panel of you LabVIEW code.
c.
Procedures
Describe the procedures used to collect and analyze data. Remember, this is not a description of
your LabVIEW code, but how you conducted the experiment (what you did with the code).
d. Calculations
Describe the calculations that you performed to estimate the fundamental frequency of the beam.
Also include a calculation of the influence of the accelerometer on the beam vibration.
III. RESULTS
Present the results of the experiment. Write just enough text so that a reader will understand the content of the
results. Include figure titles and captions, and clearly label graph axes with variable names and units.
a.
Fundamental Frequencies (high sampling frequency)
1. Create graphs of acceleration versus time for the vibrating beam that show: 1) the overall
waveform, and 2) a few oscillations with data points marked.
2. Create graphs of the FFT output (plots of amplitude versus frequency) that show the first three
modes of oscillation. Indicate clearly what the plots show (the amplitude measure and scaling that
you used).
3. Create a table that shows the repeat measures of the first three modal frequency values, and the
averages and standard deviations.
b. Sampling Rate Effects (undersampling)
1. Plot the waveforms sampled at the rates given in the experiment guidelines.
2. Create a table of the values reported by FFT for the fundamental mode at the various sampling
rates, and the averages and standard deviations.
c.
Calculations
1. Present the results of your calculations for the beam fundamental frequency and the influence of
the accelerometer on the frequency.
2. Be sure to include all of the values for the variables used in the equations as well as the
calculation results.
IV. ANALYSIS
Interpret the results. Discuss both the time domain (waveform) and frequency domain (FFT) results. Compare
measured results with expected results. Discuss any discrepancies. Interpret the effects of sampling rate with
respect to the guidelines described in class (high, intermediate, and low sampling rates, with respect to the
fundamental mode). Organize content in parallel with the Results section.
V. CONCLUSIONS
List without elaboration the conclusions that are supported by the results of the experiment. Address the
fundamental mode of the beam, and the effects of sampling rate on the waveform and apparent frequency
content of the signal.