Thinking of starting a new project...

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Re: Thinking of starting a new project...

Postby GregM » Mon Mar 04, 2019 10:30 pm

Not to pour cold water on this but maybe I am, I am an engineer as well.

I think the brute force approach of placing a couple of pressure / angle sensors / accelerometers will not work for skiing. There are multiple reasons just to list a few:
-- Immediate feedback is not as important as it seems. I view skiing as a mostly prediction activity -- in order to get where you need to be at any moment you have to set up and do so many things in advance way before that. Let's say you messed up the transition and will be in recovery mode for the rest of the turn. Will you be trying to tip more when the turn is ruined already? Being able to tip more in certain phase of the turn is possible because I set it up way before and not by doing one move, but by multiple sequential activities. Similar examples can go on and on.
-- How would you decide on the needed CA / CB or an arms position based on the pressure on the sole or angle of the boot? What if you counter rotate the shoulders but not hips? So are you going to put more sensors around the body? The challenge will be mind boggling -- measuring sensors output is not hard, coordinating all this information and most importantly providing meaningful advice based on it seem not so easy.
-- Watch multiple robots skiing on youtube. This is the state of the art and it looks ugly.

What if I place tiny sensors on the fingers of both hands and record the information and then for example would try to teach someone to play piano based on such setup? I think you are talking about similar challenge.
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Re: Thinking of starting a new project...

Postby Max_501 » Tue Mar 05, 2019 7:31 am

GregM wrote:-- Immediate feedback is not as important as it seems. I view skiing as a mostly prediction activity -- in order to get where you need to be at any moment you have to set up and do so many things in advance way before that. Let's say you messed up the transition and will be in recovery mode for the rest of the turn.


At camp its not uncommon to hear real-time feedback of tip more, flex more, pullback more, CB more, 'name the Essential' more. More, more, more!
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Re: Thinking of starting a new project...

Postby noobSkier » Tue Mar 05, 2019 1:53 pm

GregM,

It sounds like you aren't really grasping what we are trying to accomplish. No-one is saying that this would replace coaching or video. Potentially it could be useful in some narrow use cases. I think it's an impossible task to strap sensors all over the body and try to get something useful out of that. Getting useful information about tipping (by far the most common SMIM) is quite attainable.

I've built an early prototype, here is a chart with a few arcs from my live skiing. Negative values are right-foot turns, positive values are left-foot turns. The sensors measure angle. Although there are issues with my skiing, tipping is my strongest essential. Look at the consistency in inside/outside ski angle. The sinusoidal nature of the data indicates progressive tipping into the arc and through the release. You can use your engineering skills to figure out where inside ski tipping is occurring :) I haven't tried this on weaker skier, but I suspect their chart would look a lot different.

Image
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Re: Thinking of starting a new project...

Postby oggy » Tue Mar 05, 2019 2:36 pm

Awesome! What kind of sensors did you end up using?
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Re: Thinking of starting a new project...

Postby noobSkier » Tue Mar 05, 2019 2:59 pm

MPU6050 acelerometor/gyro. Turns out you need a gyro for pitch/roll ongoing error correction. Yaw is also possible but you need a magnetometer for error correction.
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