eli5 how does a pedometer have any idea how fast im walking on a treadmill?
In: 9
they don’t. More advanced models make an estimate based on your height and how many steps you take, and how quickly you take them. They can be right alot of the time, but in reality, they don’t actually know.
The pedometer counts the number of steps that you’re taking.
It then calculates distance by multiplying the number of steps by the length of your stride.
Let’s say that a person has a hypothetical stride of 20 cm (for an adult, it should be more, but I’m working with a number that will be simple to multiply). If the person takes 100 steps, the pedometer would calculate a distance of 100 x 20 cm = 2000 cm (or 20 metres).
To figure out speed, it works out how far you would travel if you walked or ran continuously for an hour at your present pace.
So, if the hypothetical person takes 15 minutes to walk those 20m, the pedometer would multiply by 4 to work out how far they would theoretically go in an hour. 20m x 4 = 80m per hour.
Obviously, because a real person on a treadmill would not be going so slowly, the figures are given in miles or kilometres per hour.
Pedometers use little accelerometers to detect up/down cycles, each of which is counted as a step. Simple pedometers cannot tell between walking or just being shaken. More advanced devices apply logical filtering to screen for specific movement parameters (such as timing, magnitude, etc.) which are consistent with walking.
A pedometer does not measure speed, it counts your steps.
When you walk or run, your body moves up and down. The pedometer can feel these movements because it has a special sensor inside. On a mechanical pedometer, this sensor is a tiny seesaw that tilts with each step you take. Most people use their phones or watches today, which would use an accelerometer for the same purpose (sensing these types of movements)
Every time this seesaw tilts, the pedometer says, “Ah, that’s a step!” and adds one to the step count it keeps track of for you. So, by feeling the motion of your body, the pedometer can tell how many steps you’ve taken.
The device has sensors and tries to identify up and down movements, which it then counts as steps, and then uses a simple guess on how long your average step is times how many up/down cycles it counted to give you a distance (or step count). They aren’t extremely accurate on a treadmill or otherwise.
Well you’re supposed to calibrate a pedometer, but I’m pretty sure most people don’t do that. A pedometer usually has some kind of setting where you determine what your stride length is and set the pedometer to that. So when the pedometer measures your steps, the distance is approximately correct.
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