CanSat help needed with Dead Reckoning

Australian version of the US CANSAT program, designed to engage upper secondary school students in the science of rocketry.

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Lneuner
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CanSat help needed with Dead Reckoning

Postby Lneuner » Mon Jun 18, 2012 9:22 pm

Hi there

I am a Maths major student with little physics and engineering background. I'm a member of my university's space and astronomy club and we're building a CanSat as a project ( http://en.wikipedia.org/wiki/CanSat ).

I have been given the task of mapping the Cansat's coordinates without the use of gps. The idea is to use the onboard accelerometer, gyroscope and magnetometer to calculate the CanSat's acceleration and hence velocity and displacement. The CanSat will also have a gps onboard and the goal is to see how accurate we can keep track of its path

I'm not quite sure how this can be done though (ie what equations to use). It's not so straightforward as the accelerometer only gives the acceleration vector w.r.t the CanSat's axis and not the earth's (hence the gyro and magnetometer).

I was hoping someone could explain how this could be done or refer me to a link where I could read up on this

Thank you in advance

*Edit: After doing some research, I realize that what I need help with is actually called "Dead Reckoning"

rocket_troy
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Re: CanSat help needed with Dead Reckoning

Postby rocket_troy » Tue Jun 19, 2012 4:50 pm

That is a challenging task which as you say, is not straightforward. Just for interest, what computing capability are you planning on processing the inertial data with? What sensors (or package) are you using for accelerometer and gyro?

TP
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air.command
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Re: CanSat help needed with Dead Reckoning

Postby air.command » Tue Jun 19, 2012 5:28 pm

This sounds like an interesting and quite a challenging project. I assume you are trying to track the entire path of the can sat from launch to landing. Coping with rocket spin and complex motion under a parachute will be a challenge. Along with the magnetometer, you may be able to use an additional sun or horizon sensor to help give you some kind of absolute reference in order to reduce cumulative errors.
Crop Circles: ... just a bunch of guys looking for their rockets ....

rocket_troy
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Re: CanSat help needed with Dead Reckoning

Postby rocket_troy » Tue Jun 19, 2012 5:57 pm

yeah, George's suggestions are (as typically expected) good ones. There's also an article in Feb 2011 of Rockets Magazine by Frank Hermes that's probably worth a read too regarding MEMS gyros and how he interfaced with them.

TP
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