Electronics Virgin, Athletics Coach and Dad needs some help !!!! - Page 1
Forum section: electronics / beginners

author: big wazza
author_rank: Newbie
timestamp: September 14, 2014, 01:08:00 pm
content: Hi ThereI apologise if I break any forum ettiquette and if I am posting in the wrong place.Here is what I want to do.I want to create in principal Telemetry for an Athlete in principal sprinters (I am a sprints coach)I know that I need an accelerometer and some form of load sensor with a physical switch and bluetooth capabilities.What I want to do is create something that an athlete straps to foot plate of track spikes. The accelerometer can measure the speed and the motion and the load sensor can measure the force of the foot strike, the length of time of the strike, and number of foot strikes and frequency.This data can then be converted in to determine such useful information, more than the information above but I am sure you can then calculate stride length, knee lift, cadence etc.The bluetooth capabilities are obvious so it can be written to an app but usb could suffice initially for test purposes so you just plug in after a run.My trouble is I need some advice lol as I am just a dad !!!ThanksWarren

author: miguelvp
author_rank: Super Contributor
timestamp: September 14, 2014, 07:43:35 pm
content: Maybe the TI Chronos watch?http://processors.wiki.ti.com/index.php/EZ430-ChronosYou can always take it out of the casing or modify it to be used as an ankle strap.But you will need to know how to program to make custom software for your needs both for the watch part and for the receiver end.

author: big wazza
author_rank: Newbie
timestamp: September 14, 2014, 08:10:03 pm
content: WOW thank you so so muchThat is a great starting point and in fact I have just ordered one straight away.....Project starts today for real .....Day 1 :-)So.....millions of questions now lol.

author: miguelvp
author_rank: Super Contributor
timestamp: September 15, 2014, 04:40:53 am
content: I do have one that is in the queue of things to use.But you probably will be able to get more help from the TI chronos forums.btw, they do sell heart monitoring chest bands in one of those links, they ones are for short distance since they just communicate with the watch. The company that sells them offer other longer range chest bands but those only monitor the heart and communicate directly to a base station. The link should be in that page above.I think they are around 50 euros a pop for the short range ones if you need to monitor heart rate.

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 15, 2014, 05:06:32 am
content: Assuming you already know about the Nike+ wireless shoe sensor which works with Apple Ipod Touch or Iphone, etc.http://en.wikipedia.org/wiki/Nike%2BThere are several projects documented online that hack into this transducer/transmitter (so you aren't locked into using an expensive and limited Apple Igadget.And there are many projects documented online for sensing heart rate, blood oxygenation, etc. using fingertip or ear-lobe transducers.And relatively low-cost commercial wireless chest straps that measure and send respiration rate (and depth?) and heart rate (and maybe simple EKG waveform?)Not clear how you can calculate knee lift (angle degrees?) or stride length from force and time data?GPS is used for calculating speed/distance (which can be divided by stride frequency to establish stride length.You could have the runner strap on a flex transducer (or two) which could measure hip and knee angles.

author: big wazza
author_rank: Newbie
timestamp: September 15, 2014, 09:34:16 am
content: The Nike version I feel is a glorified pedometer that is not very accurate either.If I can link a pressure sensor into the TI that measures Force that would be awesome.Force = Power out of the starting blocks, Will detail differences between each leg (2sensors), strike time, strike force, strike count, power during drive phase, etcAccelerometer - speed of actions, reactions, unnecessary sideways movement with triaxial,Altometer in the TI - is it sensitive enough to measure small increments as this would monitor the lift of foot which with some formula will work out knee lift.Then I would think the accelerometer data (speed) coupled with pressure sensor data of time between foot strike will calculate stride length if calibrated over set distance.2 sensors would be incredible to establish physiological differences between athletes legs that are maybe unnoticeable to naked eye like forces applied etcIm so excited right now lol

author: Rerouter
author_rank: Super Contributor
timestamp: September 15, 2014, 10:18:12 am
content: An altimeter (Barometer?) generally has a resolving time of about 1 per second from what i have seen, so you may want to attack it slightly differently,I admit i have only breifly looked over some in motion frame by frames of people running to work out the approximate motion to follow, and its seeming more like you want both a gyroscope and an accelerometer, without a barometer,With a mems 3 axis gyroscope and accelerometer it is easy to represent the stride in vectors of motion, this way on the leg curl you can determine the knee lift, the leg angle and even foot rotation, (you may need to clean up the gyroscope drift a little, however unless they are running serpentine it should be clear how to correct the data,) stride length should be possible, however i am not quite sure what you could use for a pressure sensor for the impact.

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 15, 2014, 11:10:04 am
content: The Nike+ has an analog transducer, not a simple switch. It apparently is able to distinguish between walking and running.Pressure-based sensors don't have the resolution (scale or time) to sense movement even as fast as walking, much less running.But modern devices like 9DOF chips probably give you enough raw data for most of what you want.https://www.sparkfun.com/products/12636But you will have some significant research and development to work out how to use all that data.