For this lab we will be using the strain gage to find the deflection of a bar, a piece sensor to find to mind the natural frequency of the strip with a weight on the end, and lastly a potentiometer to find an angle. Procedure: Exercise 1: The strain gage was the first experiment that was done. Calibrating this device was done using five points. The points were chosen to cover the range that we ill want to measure. We used the tow extreme ends, the center, and a point on either side of the center. Exercise 2: Piece material will create electricity depending on how fast it is vibrating. Size material creates electricity according to the rate of change, so if the material is bovine slowly then no electricity will be detected. Knowing this we can find the natural frequency of this strip with a weight on the end. Exercise 3: Potentiometers are user as variable resistors. Knowing that, we can take resistance values at given angles, then use those to find angles in between. A critical step in this exercise is to guess the angle as close to its true value as you can. After you have found your values you can use those values to calibrate the system.
After calibration the system will read the incoming voltage and correlate hat to an angle measurement. Exercise 4: Using the infrared sensor we are able to find how far away some thing is. We took readings at measured intervals and correlated those readings to the measured distances. Results: This was a quick exercise. Take readings at five deflection points and record those values in the program as seen below. The program calculated the slope of the line at 0. 268 and the y-intercept at 0. 0841. The measured values lined up very well and after we could flex the bar and repeat the results.
Figure 1: Shows the Calibration points that were used After the five points were plotted we plucked the bar and recorded the vibrations to find the natural frequency. Below are the values that we found with the average of the three trials. Trial 1 88. 60751 Trial 2 | 88. 5781 | Trial 3 1 88. 27931 Average | 88. 4883 | Figure 2: Average natural frequency Figure 3: shows the measurement of the natural frequency. This exercise included perturbing the piece material and recording the data. Below, is the graph of the vibrations induced by flicking the material. The system records these and finds the natural frequency.
Figure 4: Graph of the vibrations induced by flicking the material Figure 5: Natural frequency trial 1 1 55. 76921 trial 21 55. 50661 trial 31 55. 8491 | average | 55. 7083 | Figure 6: Recorded values of the natural frequency with the average This exercise used the potentiometer to measure the voltage at a measured angle of rotation. We recorded the measured voltage at seven different angles. Recording those numbers into the program gave back a graph and the line that went through the data. The slope was -49. 0 and the y-intercept was 215. Figure 7: shows the data and the graph of the potentiometer
Figure 8: Shows the graph of us checking the results We used a tape measure to take readings at precise distances. We recorded those measured values and the program graphed the points. This exercise was by far the most unreliable. The data had a trend but was not that close to the calibration line. Figure 9: calibrating the infrared sensor Figure 10: Using the sensor Conclusion: This lab was useful to get grasp of the importance of calibrating sensors. The calibration makes a connection between the values that the sensor is giving back to a real world measurement.