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VEX Accelerometers - How are you using them? 
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Post VEX Accelerometers - How are you using them?
Hey Everyone,

Part of what our team tries to do is provide thorough tutorials for programming. For instance, we write blog posts like this one for the VEX Gyro: http://www.robotc.net/blog/?p=1444 and all of the videos in the VEX Cortex Video Trainer: http://www.education.rec.ri.cmu.edu/products/teaching_robotc_cortex/index.html

We're planning to do the same for the VEX Accelerometer, but we'd love some input from you to make sure what we cover is useful/applicable. So how about it - how do you use the accelerometer on your robots? All ideas are good ideas, but keep in mind that we'll be trying to keep the applications more on the simple side for the tutorials.

Some things we're considering:
- Have the robot wait for a bump/tap before running it's program (pretty simple)
- Have the robot detect a collision and stop while it's running autonomously (less simple)

Thanks in advance!

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Wed Oct 19, 2011 10:46 am
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Post Re: VEX Accelerometers - How are you using them?
You have my attention. I plan on using both a Gyro & Accelerometer in an underwater robot. I plan on tracking both position & heading. I am just starting the code for the robot & have yet to start on any sensors.


Thu Oct 20, 2011 7:49 am
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Post Re: VEX Accelerometers - How are you using them?
Sounds like an incredibly cool project. I'd love to see pictures of the bot if you have any.

When you figure it out, let me know what accelerometer behaviors it uses and I'll try to incorporate them.

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Fri Oct 21, 2011 2:51 pm
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Post Re: VEX Accelerometers - How are you using them?
jbflot wrote:
We're planning to do the same for the VEX Accelerometer, but we'd love some input from you to make sure what we cover is useful/applicable. So how about it - how do you use the accelerometer on your robots? All ideas are good ideas, but keep in mind that we'll be trying to keep the applications more on the simple side for the tutorials.

I don't use the VEX platform, I use the NXT. But accelerometer use should be platform independent. When considering the use of accelerometer, I would think about detecting some sort of tilt of the robot, usually in some sort of balancing task (e.g. segway, detecting slope). I know segway is probably too complex for tutorials so any application that need to detect tilt and do something about it should be good.


Fri Oct 21, 2011 3:27 pm
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Post Re: VEX Accelerometers - How are you using them?
Quote:
...any application that need to detect tilt and do something about it should be good.


Great stuff, thanks. This confirms one of the applications I was considering. I have an accelerometer on a mobile robot's arm to see if I could reliably keep the arm level as the robot moves up and down a ramp.

It seems like it would also be one of the most useful applications, but also one that will probably require some multitasking to accomplish.

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Fri Oct 21, 2011 3:58 pm
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Post Re: VEX Accelerometers - How are you using them?
Well, this has been said, but determining position or displacement by double integrating the acceleration. That would be extremely useful.

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Fri Oct 21, 2011 4:26 pm
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Post Re: VEX Accelerometers - How are you using them?
magicode wrote:
Well, this has been said, but determining position or displacement by double integrating the acceleration. That would be extremely useful.

I have attempted that. However, the result was not great because double integration is very sensitive to sensor noise, so you will have serious drifting problem. I wouldn't encourage that especially in a tutorial.
http://proj.titanrobotics.net/hg/Ftc/20 ... ib/accel.h


Fri Oct 21, 2011 4:58 pm
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Post Re: VEX Accelerometers - How are you using them?
Yes, I attempted doing this too, and it didn't work too well either. That's why maybe an advanced tutorial would help. Just knowing that it can be done would help. And if it can't be done then knowing that helps too.

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Fri Oct 21, 2011 8:25 pm
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