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This is ace (Dave Smith, if you got an i-phone, you got to get this!)
"The frequency data can be converted to velocity (touch integrate once) or displacement ( touch integrate again). The values reported are in mm/sec (in/sec) for velocity and mm (in) for displacement."
Just a shame you can't put it under your foot, but you can strap it your leg etc....I got projects coming out of my ears. And all for a couple of quid. Brilliant!!!!!!!!!!!!!!!!
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
These apps appear to give potential for highly sophisticated movement analyses. The key is going to be in attaching the iphone to the segment of choice and to minimise movement error between the phone and the body segment, I thought about super-glue, but perhaps not.... any ideas?
My mrs uses a neoprene cuff around her arm when she uses her iphone for running etc. Would something like that do the trick? The phone doesn't move at all in the cuff. Might have potential source of error with the cuff moving relative to the body segment though?
My mrs uses a neoprene cuff around her arm when she uses her iphone for running etc. Would something like that do the trick? The phone doesn't move at all in the cuff. Might have potential source of error with the cuff moving relative to the body segment though?
Got one on my desk at work.... haven't had chance to try it yet, need to take the case off my phone to fit it in... Can't get it tight enough to fit around the distal leg though.. I might need to modify it... It may be a gaffer tape job though.
Thanks for highlighting this Simon!
Do you have a iPhone 4?
Another option is using a iPod touch- the latest generation also has the gyroscope of the iPhone 4, and is lighter (and cheaper)
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Craig Tanner
Podiatrist ASPETAR-
Qatar Orthopaedic and Sports Medicine Hospital
Doha
QATAR http://www.aspetar.com/
Thanks for highlighting this Simon!
Do you have a iPhone 4?
Another option is using a iPod touch- the latest generation also has the gyroscope of the iPhone 4, and is lighter (and cheaper)
I'm an i-phone 4 man, myself. I can't believe how cool this is. It's just a shame that the i-phone isn't about a quarter of the size it is. never the less, I'm going to collect some data and see what we can see. Between day error first.
Just collected acceleration data using the vibration app. I-phone attached to distal tibia. Running shod (Nike Zoom Elite) versus barefoot treadmill running, running speed constant between trials. Sample frequency 50HZ , acquisition time 17.96 seconds. Here's the results:
SHOD:
RMS (root mean square) X =+ 0.721g
RMS Y = + 0.598g
RMS Z = +0.868g
Hey that's really cool eh! Makes you wonder about the reliability of the data when pro accelerometer sets with software cost 100's to thousands. However making comparatives between 'normal' and pathological gate might be useful.
Dave
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Descartes seems to consider here that beliefs formed by pure reasoning are less doubtful than those formed through perception.
Hey that's really cool eh! Makes you wonder about the reliability of the data when pro accelerometer sets with software cost 100's to thousands. However making comparatives between 'normal' and pathological gate might be useful.
Looks impressive. Doesn't say if/how the signal raw data is processed, like is it smoothed, filtered, windowed, and is/can biasing be removed. I don't know what a hamming window is do you? OK now I do - go here -
Looks impressive. Doesn't say if/how the signal raw data is processed, like is it smoothed, filtered, windowed, and is/can biasing be removed. I don't know what a hamming window is do you? OK now I do - go here -
Although I actually think this app is better: http://www.wavefrontlabs.com/Wavefro...nsor_Data.html
You have to import the data into a spreadsheet programme, e.g. excel to create charts and analyse; also their is no capacity to trigger data capture- but again the developers are open to suggestions.
Been playing with this on my old Iphone (no gyro). Accel graph is a nice app, easy to use.
Simon, name your segment, I'll make you something to hold the phone to it. Software and electronics I'm not so hot. Hardware and such, I can do. Thin layer of Gel to adhere to the skin, moulded EVA to hold it vertical. Simples.
Duly Noted. You got a suit of armour on it as well. I'll take that into account too.
I have Gyro envy.
Suit of armour is removable. I got a cheap plastic case that the iphone will clip into, I was going to use this with some gel/ carpet tape on the back and a couple of straps, but if you can create something better......
The easiest and most secure way to simply attatch it is with a strip of theraband. However if the phone is not flat to the frontal plane, will it not cause a paralax error? For eg, my phone has the x axis pointing down the short side. If the device is in the frontal plane, this will not change during extension / flexion. However if the device is at 45 degrees then we see x change.
And if I Do hold it to the frontal plane (and I have a prototype which does this) what of the rotation of the leg? If I was trying to get sagittal plane data, the frontal plane rotation changes my readings!
Also, what postion do I place the leg in when aligning the device to the frontal plane. RSCP? NSCP? Based on the tibial tuberoscity?
I Wondered if one can manually calibrate the data. Ie, have the patient stand still for 10 seconds before walking and deduct the XYand Z value from the dynamic data (simulating a baseline).
Hmmm. Bit tricky this. I've made 3 rigs, all of which hold the device securely in place with little or no movement, but I don't know WHERE i am trying to hold it and relative to what. Or am I trying to calibrate my own base position?
Had another idea though. Strap the phone to the sole of the foot and use it to examine sub talar range and axis of motion (use a low pass filter). Thats crazy fun. Wonder if you could build a shoe with a segment in the sole for the phone.
Get an iphone 4 with a gyroscope so you know the rotations!
Might be worth checking the literature to see how this has been approached previously. Google: tibial acceleration
Quote:
Originally Posted by Robertisaacs
Been mulling / playing. Hit a snag.
The easiest and most secure way to simply attatch it is with a strip of theraband. However if the phone is not flat to the frontal plane, will it not cause a paralax error? For eg, my phone has the x axis pointing down the short side. If the device is in the frontal plane, this will not change during extension / flexion. However if the device is at 45 degrees then we see x change.
And if I Do hold it to the frontal plane (and I have a prototype which does this) what of the rotation of the leg? If I was trying to get sagittal plane data, the frontal plane rotation changes my readings!
Also, what postion do I place the leg in when aligning the device to the frontal plane. RSCP? NSCP? Based on the tibial tuberoscity?
I Wondered if one can manually calibrate the data. Ie, have the patient stand still for 10 seconds before walking and deduct the XYand Z value from the dynamic data (simulating a baseline).
Hmmm. Bit tricky this. I've made 3 rigs, all of which hold the device securely in place with little or no movement, but I don't know WHERE i am trying to hold it and relative to what. Or am I trying to calibrate my own base position?
Had another idea though. Strap the phone to the sole of the foot and use it to examine sub talar range and axis of motion (use a low pass filter). Thats crazy fun. Wonder if you could build a shoe with a segment in the sole for the phone.
iPhone accelerometer.
Linear Mode
