Building a pedometer

[alvin_lee]

HI there,

I am currently involved in a project which require me to build a device to count the number of steps a person will take while he/she is jogging. Looking through the web, the only product i can find is a pedometer. Can anyone tell me the engineering behind a pedometer. Like what's is it made of, how it works and the feasibility of building one from scratch.

Also, is there another way of building a device which fits into my product description?

Thanks alot

 

[evandude]

pedometers just use accelerometers. an accelerometer is a device that measures acceleration in one or more directions. by tracking the forward/back acceleration of a person's leg, you can quite easily find out how many steps they took. shouldn't be hard to build from scratch, depending on what accelerometer you choose. analog devices makes some with PWM or analog outputs I believe (ADXL202 comes to mind) that makes them easy to interface with a microcontroller.

if you visit sparkfun.com they have all sorts of products dealing with the ADXL accelerometers, from the chips themselves, to breakout boards, to serial interface boards, and even assembled, ready-to-use serial accelerometers.

 

[vaineo]

I'm not sure where your from, but they have been giving those away at McDonalds and in some boxes of cereal. MAybe you could get one of those and take it apart see how they did it.

 

[Someone Electro]

Put a pece of metal on a spring wich wod swing to a contact.Put it in a smal box and atach it to your leg.Evry step the metal pice swings to the contact making pulses.Feed this to a micocontroler wich wod drive a display.

 

[evandude]

yeah, that might work if you took very smooth, controlled steps, but what if you were walking more roughly? or running? the spring would be bouncing all over the place and you'd get all sorts of false contacts.

 

[grrr_arrghh]

yeah, that might work if you took very smooth, controlled steps, but what if you were walking more roughly? or running? the spring would be bouncing all over the place and you'd get all sorts of false contacts.

acutally, many comercial pedometers use this method. Mine is not affected by running, but doesn't work is you try to use it sideways! As long as the spring is fairly taught, and its natural frequency isn't the same as the frequency of the steps that you are likely to take, it should be fine.

 

[alvin_lee]

Thanks guys, just one more question

Hey guys, thanks for all the advice. Just one more question. Other than using or building a pedometer, is there any other way to determine the number of pace a jogger will take in his/her jog? i am suppose to be able to store 60 mins worth of data.

I have thought of using a IR emitter and a photodiode both attached on the same leg. Its is base on the theory that IR will bounce off a surface(when the jogger cuts the beam of the IR) and subsequently detected by the photodiode. Is my theory feasible. Pls advice further. I will like to know if there are any other ways. It will give me more options to complete my project.

Thanks alot