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Sensors and Transducers 91

calculated, not marked but requires less setup time, is more portable, and
allows for greater movement freedom for the subject (Sigal et al., 2010).
Despite all the other tests Jacob has performed, you decide that his gait
data will be the most telling for determining how his new prosthesis com-
pares with his old one. You coordinate with the local university and arrange
to get access and support for evaluating Jacob’s gait with the two prostheses.
On the specified day, you and Jacob arrive at the lab and the lab tech-
nicians help Jacob get himself and his two prostheses marked with the IR
reflection balls. Once the balls are in place and the system is calibrated to
Jacob, the lab supervisor and technicians ask Jacob to walk back and forth
along a specific line. Using a self-selected gait, they also ask Jacob to try
to time his steps such that his prosthetic leg lands squarely on the load cell
on the floor of the lab. Jacob complies and is able to get some good gait data
for both prosthetic devices.
With the help of the lab supervisor, you are able to analyze the gait data
and are able to determine many things about Jacob’s gait with his two
devices. You can determine the rate of his self-selected gait, the joint loads
and moments, velocities, and accelerations. With the gait data, you can tell
Jacob how his gait changes between each device and how those gait patterns
compare with the gait of a person without limb loss.

7 CONCLUSION

In this chapter, we have discussed what a sensor is and some key char-
acteristics of all sensors. We have also discussed some passive sensors, simple
sensors, common sensors, and a variety of biological sensors. As was men-
tioned previously, this chapter does not cover all sensor technologies, but
is an introduction to those sensors and systems which many be encountered
in biomechanical design. Use this information to begin your own explora-
tions into sensing technologies.

REFERENCES
Allegromicro, n.d. List of available Hall effect sensors from Allegro Microsystems. Available
from: https://www.allegromicro.com/en/Products/Magnetic-Digital-Position-Sensor-
ICs.aspx (Accessed 22 August 2017).
Basmajian, J.V., de Luca, C.J., 1985. Muscles Alive – The Functions Revealed by Electro-
myography. The Williams & Wilkins Company, Baltimore.
Bolton, W., 2003a. Mechatronics - Electrical Control Systems in Mechanical and Electrical
Engineering, third ed. Pearson Education Limited, Harlow, England (Section 2.2).
Bolton, W., 2003b. Mechatronics - Electrical Control Systems in Mechanical and Electrical
Engineering, third ed. Pearson Education Limited, Harlow, England (Section 2.3.3).