Performance Characteristics of Sensors and Actuators

  • The performance characteristics of the device or system are the most important issues the engineer is faced with.
  • The properties of sensors and actuators are usually given by the manufacturer and engineers can usually rely on these data.
  • We can describe both types of devices by a transfer function that relates input and output regardless of what these quantities are.

The transfer function

  • The input/output characteristic function or response of a device is a relationship between the output and input of the device, usually defined by some kind of mathematical equation and a descriptive curve or graphical representation in a given range of inputs and outputs.
  • With the exception of linear transfer functions, it is usually difficult to describe the transfer function mathematically.

In [22]:
import matplotlib.pyplot as plt
import numpy as np
%matplotlib inline

x = np.array([226, 248, 278, 369, 532, 718])
y = np.array([154, 155, 166, 219, 289, 314])
y = np.abs(y-350)

a,b,c,d,e = np.polyfit(x,y,4)

y2 = a*x**4+b*x**3+c*x**2+d*x+e

plt.xkcd()  # Yes...
plt.plot(x,y2)
plt.axis([200,800,20,220])
plt.xlabel('T')
plt.ylabel('R')
plt.show()



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