North Tahoe High School Students and their Autonomous Cataraft!

Ken Gracey · 2013-02-28 14:57

Hey all,

I have volunteered steadily over the last year at our local middle and high school to start up a robotics program http://forums.parallax.com/entry.php/833-Parallax-President-Ken-Gracey-gets-Hands-on-Teaching-Robotics. This year, the high school teacher Ms. Butterworth gave the students the opportunity to do a full-semester project in robotics. Zachary, Alex and Patrick chose the following mission:

Design and build a cataraft that can autonomously navigate the surface of Lake Tahoe, using GPS waypoints

Lake Tahoe is an oligotrophic lake (low of polluting nutrients, providing clarity up to 100 feet). At one time Lake Tahoe could have been a National Park, but too much development had already occurred between the silver Comstock logging era in the 1800s and vacation housing the last century. In the last 40 years, a bi-state agency under Federal mandate was formed to retain the quality of the lake. Numerous research-oriented efforts now take place in Lake Tahoe, from UC Davis to private underwater robotic efforts. Everything from fish (you may have read about the giant goldfish recently discovered in the lake), air quality, runoff, noise and historical geography is studied here. It only seemed fitting that high school students also get part of this experience with their attempt.

Their project has been taken in steps:

Design the craft.
Build it.
Test stability of the system in the water (today's effort).
Add R/C control.
Add GPS and Propeller for autonomous navigation. I'll be helping here a whole bunch - their programming experience is limited to Boe-Bots.
Program for a GPS waypoint test, sending the craft miles out in the lake..

I meet with them once a week for a couple of hours, and they basically do the project on their own with feedback from myself and Ms. Butterworth. It's never enough time, of course, but it's probably best this way because this is their project and I'm merely a consultant they can listen to or ignore. It's been really interesting watching them choose fasteners, materials, tools and put it all together. Each step includes an internet search, a calculation or two, and a milestone that has some level of success or failure. I keep telling them "it's the real deal!" and that these are important steps in the process of creating such a project. We're learning, by doing. They keep engineering notebooks to turn in to their teacher.

So we went down to the lake today. Zach and Alex put on their waders and they carried the craft into the lake. Right away we noticed some problems: it wasn't nearly as buoyant as we had calculated it to be; the hulls were taking on some water through their 3-D ABS printed nosecones (which are solid, and heavy) which were not properly sealed; and that the whole system weighs more than we initially projected with the big batteries. So we pulled it from the lake and they seemed a bit deflated.

Now they've decided to go to 6" ABS with caps, and they won't violate the chamber after it's sealed. I might also bring them a Minn Kota trolling motor (we're currently using Crustcrawler thrusters).

We have until June to make progress, and I'll update this thread as we proceed. At some point you'll see these students here on the forum. They're fantastic people (Eagle Scouts, volunteers, job holders at the hardware store) and full of laughs and good jokes. They could probably use a bit of encouragement right now, so...

Ken Gracey

Ttailspin · 2013-02-28 15:31

It floats! :thumb::thumb:

Triple expanding foam works wonders for making all kinds of things float better.
It's like life jackets and floaties, all in one can...:)

-Tommy

erco · 2013-02-28 15:55

Cool project!

COLD project! What's the water temperature? I ran a marathon at Lake Tahoe in October many moons ago. It was so cold that the gels in my fanny pack froze during the run.

Martin_H · 2013-02-28 17:42

Great project. I still haven't used my GPS and I bought it specifically for way point navigation.

erco · 2013-02-28 18:17

Me too, Martin_H. I guess the race is ON!

Duane, you want in?

TinkersALot · 2013-02-28 18:46

Dang~ I want to be in that class!

Phil Pilgrim (PhiPi) · 2013-02-28 18:54

That's a really cool learning project for the students! Regarding the floatation issue, one of the most important take-aways has to be, "Never be afraid to make mistakes." I mean, what do we remember longer? Doing it right the first time? Or having to go back and figure out what went wrong and how to fix it?

Ken, our local school district may soon be refocusing their curriculum to center around a maritime theme. As a consequence, the local professional community will almost certainly be called upon for assistance, and I suspect that my name will come up in the process. If so, I might need to consult with you about matters related to volunteer teaching, since, though not unwilling, I'm completely clueless (and a bit terrified by the prospect).

-Phil

Tex4u · 2013-02-28 19:38

Ken, I look forward to seeing more from this project. Love this kind of exposure to HS students. What a fantastic opportunity. Kudos to the project organizers.

Frank

erco · 2013-02-28 20:33

Flotation-wise, Archimedes was a smart cookie and a tough act to follow.

Further, his "screw" inspired me thus: http://www.youtube.com/watch?v=w97Yvq4d6b4&feature=player_detailpage#t=83s

Good designers borrow, great designers steal!

WBA Consulting · 2013-02-28 22:12

Great project! I can see many different aspects of robotics, electronics, engineering, watercraft design, etc, etc, falling into play.

I couldn't find it from an internet search, but I recall seeing a similar project a couple years ago where the students harvested the parts from a Minn Kota trolling motor and the motor could spin 360 degrees, making the craft very maneuverable. The weight of a 12 volt deep cycle battery and trolling motor are definitely a justifiable trade-off.

How will you be tracking the craft's performance? A second GPS setup with the Google Earth datalogger code? I assume you will have a chase vehicle when you get to the "miles of travel" test?

an interesting read: http://www.panbo.com/archives/2010/05/minn_kotas_i-pilot_robot_geonav_for_real_.html

SRLM · 2013-02-28 22:36

I'm mentoring a FIRST robotics team this season, and it's been lots of fun. And, I've learned quite a bit too. The most interesting area of knowledge that I gained was in pnuematics: I had no idea that they were so powerful or easy to use. And, I've taken a few programmers under my wing and did some pre-season training for them. That was fun because it helped me solidify some of the more basic programming concepts that I had forgotten about.

rwgast_logicdesign · 2013-03-01 10:58

This is definitely cool, I look forward to seeing updates on this. Ive always been interested in autonomous boats and submarines, but being as I live in the dessert a pool is about the only way I can experiment with this stuff for myself.

It will be really cool to see this thing move to waypoints across the lake! What sort of batteries does the craft use?

Ken Gracey · 2013-04-08 22:12

April update - the high school guys Zach, Peter and Alex have rebuilt the craft with a couple of major improvements. They've gone to 10" SDR drainage pipe and switched out the Crustcrawler thrusters for a Minn Kota trolling motor. The big improvement is the increase in floatation and stability in waves, so now we'll hook up the motor to an HB-25 and get this under some R/C control on Thursday.

Ttailspin · 2013-04-09 07:29

Another fantastic prototype, Great work!
And, I see you have discovered "Nose Cones" are not all that important with a wide, slow moving watercraft...

Keep up the good fun.

-Tommy

Ken Gracey · 2013-04-09 12:55

Tommy - you are correct. Removing nose cones from the project dropped weight, and to little or no detriment of increased drag.

Ken Gracey

North Tahoe High School Students and their Autonomous Cataraft!

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