Using the data collected from our experimental run we were able to generate plots relating the input force to the output of the PFG sensor. We chose to plot the maximum percentage change in frequency on the y-axis, because it gave us a value of the overall change in frequency of the PFG sensor output when a constant force is applied. Taking the difference between the maximum and minimum frequency and then dividing it by the minimum frequency calculates the value of the maximum percentage change in frequency. As shown by equation 1 below:

Equation (1)

In table 1 we calculated the maximum percentage change in channels 1 through 7 for all forces applied in experimentation.

Table 1: Maximum percentage change in frequency calculated.

Using the maximum percentage change in frequency (%) on the y-axis and the force applied (lbs) on the x-axis we generated the scatter plot and line plot in figures 8 and 9 below.

Figure 8: Scatter plot of force applied versus maximum percentage change in frequency.

Figure 9: Plot of force applied versus maximum percentage change in frequency.

 

From these results we can see that the values calculated at 25lbs of applied force are outliers with respects to our other data points. Re-plotting our data without the values at 25lbs we get figures 10 and 11 below.

Figure 10: Scatter plot of force applied versus maximum percentage change in frequency, excluding outliers.

 

Figure 11: Plot of force applied versus maximum percentage change in frequency, excluding outliers.