What Makes a Pedometer Work?
A pedometer is a small device that counts how many steps you take. Most people just clip one to the waistband of their pants in a position where it will move when their hips move. Pedometers can be simple or multifunction, but ultimately they all count steps. Hip movement is the key factor in a pedometer's operation, but it can use different methods to get the job done.
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Oscillations
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All pedometers use some form of oscillation to count steps. When you walk, your hip causes a rhythmic movement in the pedometer that makes and breaks a circuit. These "on-off" contacts, often heard as a literal clicking inside the device, are then counted and converted into "steps." These are then counted and the result displayed to show how far you have walked.
Pendulum Sensors
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Mechanically based pedometers use a spring-loaded pendulum (or lever) that swings when your hip moves. This movement acts as a switch, making and breaking an electronic circuit that registers each "click" as a step. Mechanical pedometers like this must be positioned carefully, because gravity plays a major role in their operation. Otherwise, they may not register any steps at all.
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Piezoelectric Sensors
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Piezoelectric pedometers are less dependent on gravity than the mechanical variety. Piezoelectric materials are sensitive to vibration---they are often used as pickups for acoustic instruments, for example. This pickup is connected to a weighted lever that gets "jiggled" as you walk. The vibrations this causes in the piezoelectric pickup are then converted to the electronic equivalent of mechanical "clicks" and displayed as steps.
Calibration
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Calibration is critical to the proper operation of a pedometer. At its most basic, this involves adjusting the pedometer to "know" how long your typical step is. With some mechanical models, this can be a fairly complicated process where several variables must be adjusted, tested and readjusted until the pedometer works properly. The electronic models tend to need only a simple adjustment.
Accuracy
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No matter what technology they use, pedometers have a reputation for inaccuracy. In fact, the step counts of some models have traditionally been off by as much as 40 percent. Newer pedometers incorporate better technology to improve this problem, and accuracy is not as big a problem as it used to be. The best thing to do is read extensively about the models you are considering and see how satisfied other users are.
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References
- Photo Credit pedometer image by Andrew Brown from Fotolia.com
