Constructing a Pedometer

[WinkSB]

Hi there...i need advices on how to construct a pedometer for my project...i have no idea where to begin..kindly advise... :cry:

 

[Optikon]

Hi there...i need advices on how to construct a pedometer for my project...i have no idea where to begin..kindly advise... :cry:

If this is for school, my first piece of advise is keep it practical.
Commercial pedometers are based on some kind of repetitive movement.
There is some average distance traveled when undergoing this repetitive movement and so you can count the triggers and add up the distance electronically. These of course, would be more accurate the farther one moves. I've seen in these units a small pendulum type device that swings and probably triggers something when a step is taken.

You could do something similar but to avoid the precision mechanics involved in a balanced pendulum, I would suggest using several tilt switches oriented in such a way as the cause successive triggers as a complete step is taken. A digital circuit could monitor the sequence of triggers and "recognize" when a complete step is taken.

Once a complete step can be recognized, it is just a matter of counting the steps and multiplying that by the "average distance traveled per step" to give total distance traversed.

A way to calibrate the thing is to have the user walk a known distance and count your triggers and this tells you how many triggers to expect per unit of distance which can produce the constant described above. The longer the calibrating walk, the more accurate it will be. And for even better accuracy, throw out trigger sequences that did not register as a complete/proper sequence (i.e. some unexpected motion occured so do not count that in the average)

This seems feasible for a small scale project. It could be done with a battery for a power source, a PIC / uC, some tilt switches, a cheap LCD screen for the readouts and prompts, a couple of buttons for inputs to calibrate or count, and some misc circuits for working switches.

Does this at least seed an idea of how to begin?

 

[WinkSB]

Thanks for providing the information...I'll definitely use that to aid me in building the pedometer...I was wondering if i were to go into the technical aspects of building a pedometer...as in writing it down in a report...what should i say about?? i'm really very lost in this project that i have...

 

[stevez]

There is nothing wrong with borrowing from the past but on occasion it's worth setting a traditional method aside to explore alternatives if time/budget allows.

Just an idea - do some research (read, consult with experts) and see if there is some data available on the process of walking, particularly speed, velocity, etc of various body parts. My son is a Physical Therapist and part of his studies included the mechanical motion of the human body. With all movement or motion there is acceleration. The traditional pedometer simply signalled that acceleration/deceleration occured. An accelerometer or simply a strain gage or two, could be used to indicate how much acceleration occured, relatively speaking. With some effort and study you'd likely find that "walking" produces recognizable patterns. You may not only be able to determine the number of steps taken but also you might also roughly estimate the length of step based on prior study.

Your effort probably should be focused on electronics rather than bio-mechanics but the bio-mechanics might be a place to begin. Your project might be to build the instrument that would be used to gather data on the process of walking - at least initially. As the data is processed you might find that signals from accelerometers need little or a lot of processing to deliver meaningful information. That might point to larger, more powerful processors and software - or show that something as simple as a PIC is adequate.

I've given some thought to this myself, as an interesting project to do with my son.

 

[SBWink]

Thanks for the idea stevez...

i was thinking of buying a commercial pedometer and try to connect it to a PDA....if i can connect it and retrieve data from the pedometer, i think that'll be good enough for my project....if i cant do it wif a commercial pedometer, i think i have to come up wif a self made one, make it compatible(meaning can connect and download data to it) wif PDA......is it feasible??

 

[grrr_arrghh]

i was thinking of buying a commercial pedometer

I have a small one which uses a couple of contacts - one fixed and one on a spring. When you walk, you waist moves up and down - so the one on the spring moves and touches the other one, making a circuit, and the ammount of time this happens can be counted.

(meaning can connect and download data to it) wif PDA......is it feasible??

Doubt you will find one comercially - unless it is built into a GPS unit - also, prob not worth downloading the data - surely better to display on a display on the unit itself?

Tim