I have started a little aquatic vehicle project that will be used to do depth mapping of the various ponds, lakes, and canals where I live in southern Florida. The mapping will allow the owners to determine their silt levels and silting rates.
My RSV is based on a similar RSV, only smaller, that appeared in the July/August 2010 issue of Robot Magazine and can be seen here: eTrac RSV
I chose to use fiberglass pontoons for a .60 size R/C plane and can be seen here:
The pontoons are manufactured by Great Planes and can be found at Tower Hobbies.
For propulsion I was originally going to build a couple of small outboard electric motors using Johnson-Mayfair 750GPM bait pump cartridges and 50mm Robbe three bladed propellers.
The housing for the bait pump cartridges was going to take a little bit of machining and the jaws in my Tag lathe still needed to be machined to allow me to chuck up plastic pipe couplers that are bigger than 1" in diameter.
Since I like Traxxas products, I found that the geared propulsion system for the discontinued Villain R/C racing boat might fill the bill as there are quite a few of the legacy Villain parts to be had on eBay for cheap:-).
So I downloaded the Villain exploded hull and drive train views and the parts list and proceeded to buy what I needed to put together two of the Villain geared propulsion drive trains.
At this time, while searching for Villain parts on Amazon, I found one last Villain built hull for sale and proceeded to order it so that I can build up a competition autonomous boat for competitions like the Sparkfun AVC only on the reservoir.
I began the installation of the Villain drive trains by cutting two sections out of the right pontoon just aft of the wire connecting bridge mounting points. I reinforced the sides and ribs of the pontoon, where I removed the fiberglass glass sections, with thin strips of poplar wood.
The toughest part of mounting the drive train was spotting the hole for the stuffing tube in the pontoon stern plate and getting clearance for the motor under one of the pontoon ribs. Pictures of the installation are below:
550 motor_reduction gears_and stuffing tube
Stuffing tube exit on stern plate
The propeller drive shaft is attached to a universal joint that is coupled to a short propeller shaft that is supported by an outdrive housing that is attached to a hinged trim support that allows the pitch of the propeller to be varied up and down vertically. I plan to epoxy the motor mount to the bottom of the hull once I have installed the rest of the propulsion hardware beyond the stern plate.
Right and Left Pontoons with Bridge
More build details and pictures to come.
Regards,
TCIII ArduBoat Developer
Replies
Hi All,
GPS/Depth Finder Data Logging Code Effort:
Rusty from Blue Robotics and Burkhard Riek have both provided me with excellent Arduino code guidance and examples which will quickly allow me to determine the functionality of both the Adafruit GPS/Data logger Shield and the Intelliducer Depth Finder once the Adafruit Shield arrives this coming Wednesday.
Attaching the Depth Finder Housing to the Pontoons Effort:
On Sunday I constructed two 1/8" thick ABS plastic plates to mount on the pontoon deck ahead of the front bridge strut. The plates are as wide as the pontoon deck and are 8.5" long. At each end of the plates I have added a 2" long 1/8" thick ABS plastic plate that is the same width as the new deck plates to act as a hard point.
I have glued the two plates to their respective pontoon decks and have glued the additional 2" wide plates to each end. I plan to mount two 1/2" X 1/2" aluminum "L" extrusions approximately 22.5" in length from each 2" wide hard point on the new deck plates across to its mating hard points on the opposite pontoon. The extrusions will be spaced approximately 6.75" inches apart and will provide a bridge support from which to hang the transducer housing by threaded rods which will allow for the vertical adjustment of the housing in relation to the pontoons.
Pontoon Deck ABS Plastic Plates & 2" wide Hard Points
The extrusions will also provide a place to mount the Arduino/Shield assembly housing as well as the waterproof housing for the LiPo battery and depth finder interface terminal connections. This configuration will allow the depth finder housing and associated support components to be removed from the pontoons as one complete assembly so that the RSV can be used for other purposes in the future.
Regards,
TCIII AVD
Tom, Lookin good. I will be getting back to my build in a few days when I get done with some travelling. Keep up the good work!
Regards,
David R. Boulanger
Hi All,
I have several Arduino 328 boards laying around so I purchased a GPS/Data logger shield Link from Adafruit Industries. I could have purchased just a data logger shield and added my own GPS along with the depth finder to the data logger. However this GPS/Data logger shield also comes with an RTC, is already assembled, and is reasonably priced.
The GPS/Data logger shield comes with GPS NMEA 0183 data parsing and logging software. The code uses the Super Simple Serial library to communicate with the GPS. However, I still need to capture, parse, and log the Intelliducer depth finder depth/temperature NMEA 0183 sentences. Also, it might be good to transmit the logged data to my laptop by Xbee transmission. So I am looking at creating two additional software serial I/Os beside the built in one for the GPS.
I have been using Google to search for Arduino code examples that captures, parses and logs multiple external serial inputs to see how I need to modify the existing Adafruit GPS parsing and logging software. So far there has been no joy during my searches.
If any of the members here has Arduino programming experience and knowledge (I know just enough Arduino programming to be able to splice existing code together and get it to run without errors) I would greatly appreciate some help with this programming endeavor.
Regards,
TCIII AVD
Hey Thomas,
You might want to check out Mikal Hart's TinyGPS++ library (arduiniana.org/libraries/tinygpsplus/). The library parses NMEA-0183 strings and is capable of parsing custom NMEA strings. That's really helpful when you want to read for non-GPS devices like your depth finder. We are using the library for our ultrasonic wind sensor and it works great. It will work with SoftwareSerial or HardwareSerial.
Best,
-Rusty
Hi Rusty,
I assume that you created a second SoftwareSerial port or used a HardwareSerial port to read your additional sensor's NMEA strings and used TinyGPSCustom objects to capture and parse the non-GPS sensor NMEA strings?
Did you update your sensor NMEA data at the same time that you updated the GPS NMEA data relying on new GPS NMEA string availability to do the string capture and parsing?
The Adafruit software uses a 1ms interrupt to check for new GPS NMEA strings.
Would you mind sharing your source code so I can use it as an example?
Regards,
Tom C AVD
Hi Thomas,
Yes. We used SoftwareSerial and the TinyGPSCustom objects. Here's the code (written for the Airmar WS-100WX sensor): https://github.com/bluerobotics/SolarSurferCore/blob/master/src/Air...
We used a different TinyGPSPlus objects for the GPS and the wind sensor. New data is read during each loop of the software, no interrupt involved. Up to 128 characters are read in the loop.
I'd be happy to explain in more detail if you have any questions.
Best,
-Rusty
Hi Rutsy,
Thanks for the info, much appreciated.
I can usually write the Arduino source code if I have an example that is similar to the process that I need to write the code for.
Regards,
Tom C AVD
This may be slightly off topic, but I was was curious if using a GoPro stereo rig could also be used on your setup for bathymetric mapping. Check out this article:
"Measurement of Micro-bathymetry with a GOPRO Underwater Stereo Camera Pair"
http://ccom.unh.edu/sites/default/files/publications/PID2487337_0.pdf
@M C,
This kind of mapping appears to be used very close to the ocean floor while my depth finder setup is designed to work on the surface and penetrate water that may be optically cloudy which would obscure close to the floor optical measurements.
Regards,
TCIII AVD
Hi All,
Good news.
I took the completed Transducer/Interface Housing down to the Association swimming pool and slipped it into the water. The Housing sank a little over 1" into the water and was completely stable fore, aft, and side to side. I could let it go and it floated straight up in the water without any tendency to roll or tilt.
Now I can move on to building the electronics to capture and decode the NMEA 0183 depth and temperature sentence strings that the Interface transmits at a 4800 baud rate. I will either capture the depth and GPS sentences in a onboard data logger or transmit the data to my GCS for storage. More later.
Regards,
TCIII AVD
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