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Permalink Reply by Warren Osborne on March 8, 2011 at 4:18am

Simon

 

You certainly have access to most of the sensors you would need to do an INS for the glider. A pressure sensor for measuring the depth of the dive would probably be useful. If your hull compresses during the dive you might be able to do it via measuring the strain on the inside of the hull rather than have a penetration through the hull - minimise these, get a leak and you can probably kiss your glider goodbye. BTW, you might want to keep an eye on your glider's seals they apparently only last a few deployments.

 

I imagine currents pushing on the glider during the dive would be something you might have to live with and compensate for on the next dive after a GPS fix.

 

The ability to roll the glider during the dive might help as well - maybe by moving a weight around the long axis of the glider?

 

Have you done a search for papers on how other gliders like iRobot's Seaglider, etc navigate? Does your university have gliders already? If so, are they going to let you pull it apart... I mean examine it?

 

Of course, its all a trade off - the more electronics you put in the more current you pull from your battery and the shorter the deployment of your glider. Hope some of this helps.

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Permalink Reply by Simon Clements on March 8, 2011 at 5:56am

Thanks for your reply,

Ive read quite a number of papers on gliders so far, the general method of navigation for the gliders seems to be INS using gps gyros, accelerometers, acoustic depth sensors etc.. They also have sensors to judge the effect of currents and correct I believe at least, how ever its far to complicated on a dynamics and sensor point of view for our project so were trying to keep it simple.

We've so far opted to use a rudder similar to that used on the SLOCUM glider.. if we can seal it that is rather than a rotating mass inside to cause roll & hence yaw, as it has a smaller turning radius and we thought it might be less complicated a design. The strain gauge idea is great, definitely hadn't considered the possibility of a strain gauge to limit external sensors.

As it our project is more of a 'prove the concept' project, the ignoring of current effects isn't a great issue, so long as the system can function and when it surfaces realise its off course and correct. It all depends if we can get Ardupilot to be able to do this as we don't have much sensor/Arduino coding experience.

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