Let's Make Robots!


Measure water depths in lakes
Bilde.jpg881.9 KB
MarkII_LOG_microSD.zip2.73 KB
MarkII_NAV_microSD.zip5.11 KB
DELFTship_linesplan.pdf159.55 KB
Mark_II_versjon_1a_mod.zip9.02 KB

This is Mark II of the Whirligig project http://letsmakerobots.com/node/16995 code name SEA RENDERING (it’s not actually a code name, just an anagram for my name :-) )

The purpose of this robot is to have it log water depths along a predefined set of waypoints. It stores its data on memory sticks or on SD cards. The estimated runtime is about 24 hours and with a top speed of 3km/h it will travel roughly 72km. With a log entry for every 10m this would give us over 700 depth measurements   with full GPS reference.

Most of the control system has been moved from the original Whirligig to save cost and time.

The hull was designed in the free version of DELFTship http://www.delftship.net/ and built this winter. With the split mould I can produce a second hull in matter of days.

The original plan was two hulls working in pairs as a catamaran with a solar panel on top. This can still be done but two robots working independently we can cover a larger lake on shorter time.

Some images from the hull build

Adding fiberglass to one half of the mould

Mould completed

The first casting

Here are some pictures from the complete robot


Polymorph beddings for the batteries

Control system

Some electronics in the lid

The waypoints are entered using my adaptation of the Ardupilot tool. A great application that lets you interactively add waypoints to your list. This list is then copied onto the SD card and the robot is ready to run.

I run this routing 3 times and this is a GPS visualization of the log. The green markers are the waypoints.
(one of the log files are attached)

My brother (a professor at the University of Oslo) that will be using this robot, then run these 3 logs in something called  "Thin plate spline" http://en.wikipedia.org/wiki/Thin_plate_spline to see if the depths we logged made sense. And this is what he came up with.

All in all this project seems very promising.

Update 28/6-2010

After having had some problems with the VDIP1 USB interface I decided to go for the microSD shield from Sprakfun http://www.sparkfun.com/commerce/product_info.php?products_id=9802 .
Now the whole thing looks much cleaner and is probably more robust.



Update 11/7-2010

This weekend my brother and I went to the lake ‘Riskedalsvatnet’ to do a full scale test. The full waypoint routing had 337 waypoints and a total length of 18,1km.

The traveling speed of the boat is about 3km/h so the mission should have been completed in about 6 hours. As this was the first full scale test and we had some uncertainties on where the shore line actually where, we decided to split the trip into 3.
This is the first segment of the mission.

This is how the boat run

And this is an Dr.Depth rendering of the depths we got.

After all segments where completed this map was generated in Dr.Depth

A full size map in b/w is attached


UPDATE 14/7-2010

Added the Arduino sketch if anyone want to have a look.

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Very cool. I love anything with a GPS on it. You have probably seen this man's blog? http://diydrones.ning.com/profiles/blog/list?user=3um9qjnkq5rxo if not, it is of the same topic.

That’s a new blog for me, thanks.

Im working on a similar to this one project but the chassis its quite different .

Love to see it. Hope you post some information about it here on LMR when you are ready. so easy to do with Whirligigs current design.

Some drastic redesign of the hull. Looks a lot more energy "friendly" Was that the reason to redesign it or did the other hull cause more undesired effects?

The main reason for redesigning it was the share weight of Whirligig, fully loaded it weight 50kg. The second reason was to have a system that could run from solar cells on a later phase. That was not so easy to do with Whirligigs current design.

So nice to see all the work that goes in there. Would be nice to have a better sonar under there that can actually show shapes of the bottom (like the fancy fishfinders do). Or add some undewatervideo device to do some serious treasure hunting. With such clear water it should be possible to get proper images up to 30 meters deep (on sunny days). Just publish the images and scans on a website and let inet-volunteers look for treasures or scandinavian sea monsters :) I'm longing back to my boat days..... Was it very hard to setup the GPS system with the ardupilot?

ps Don't add the location or the treasures might be gone swiftly :)

Actually we didn’t follow the Ardupilot route but instead wrote our own navigational software. The Ardupilot was a bit over kill for our needs. I even had to write my own NMEA decode functions as the NMEA library I used stole the entire RAM and I couldn’t get it to work with the SDfat lib.

very nicely designed and built.

i love UAV's and ROV's, currently working on a UAV at school so anything of this kind has my immediate interest.

love your work


What did yo use to make the chassis (the yellow thing)?