Hitting the Water

Posted on 2013/03/10 by Duck

This weekend I had a chance put the prototype hull in the water to see how it handled. I posted a no-frills video of it below:

During the first trial I ran the boat without any additional weight. I had some trouble steering it. I attributed this to the rudder control being inverted from what I was expecting and the boat sitting high in the water. I fixed the rudder controls using a reverse switch on the transmitter. I added about 20 lbs of dive weights to get the boat to sit lower in the water. After these changes I was able to make small steering corrections easily using the rudder.

Getting the boat to make more drastic turns turned out to be difficult. I tried putting one propeller in forward and the other in reverse but this didn’t seem to have the amount of turning power I expected. Powering just one propeller forward with the other off worked better but still was no match for the winds that were blowing at the time. A combination of one propeller, rudder and luck seemed to be the only winning combination. More testing will be needed to determine the exact cause for the trouble but my current theories are:

Unequal drive power between the two motors. If this is the case, a closed loop control system can be used to fix it.
Insufficient power. For the tests I used an old 9.6V NiMH R\C battery pack to supply power to both motors. Given that the voltage sagged to below 5V during operation, it is likely that the battery pack’s ESR was too high to supply full power to both motors when I was trying to drive them at full speed in opposite directions. This problem can be eliminated by using a different type of battery or by using separate batteries for each motor. Using separate batteries has the additional bonus of redundancy.
Insufficient propulsion. The motors / propellers may need to be changed to provide more thrust.

Other things I noted during the testing:

A bumper should be added around the perimeter of the boat to protect the fiberglass when I run it into the dock or pilings.
A cage should be constructed to protect the rudders / props when the hull is set on the ground or when the stern collides with a dock / piling.
The RC Transmitter is not well suited for a boat. The port motor control uses a throttle control stick meant for an airplane; the throttle does not automatically return to zero.
The hull maintained dry despite water washing over the top of the boat occasionally.
The addition of 20 lbs of weight made the boat more stable and less tippy.
The port drive motor needs adjusted. It made a lot of noise and seemed to have less power than the starboard motor. A post inspection found the port motor shaft to be out of alignment with the propeller shaft tube. I didn’t notice this upon first running the boat so the motor support member made need additional support.
We may want to consider placing the thrust elements midships on the next version to make turning in place easier.

Grease Monkey

Posted on 2013/02/25 by Duck

This past week marked the end of the 2013 FIRST Robotics competition build season. With 3 weeks till the first competition in Long Beach, I should now have a little more time to devote to other projects.

This week I made a little progress on the Survey Boat. I first filled the propeller and rudder shafts with a marine grease. This should not only lubricate the shafts but should also keep water out.

Preparing the propeller shafts

I then installed the propellers and the rudders and connected them to the motor / servos respectively.

Propeller shafts after installation

With the shafts installed, I connected up a RC radio receiver and made sure everything worked. When I get some time this week I’ll take the boat to the harbor to get an idea of how it performs on the water.

Boat in Port

Posted on 2013/02/12 by Duck

The Boat Hull has arrived from Oregon

My friend Chris finished the prototype boat hull and shipped it from Oregon via Greyhound Bus to Ventura. I never knew Greyhound shipped packages but it makes sense. It only cost $65 to ship via bus compared to the $300 UPS would’ve charged.

The hull arrived mostly intact. The only damage was to a rudder tube which was bent and easily fixed.

In order to facilitate working on the boat, I decided to make a stand for the boat. I was able to make a basic stand with scrap from my workshop. This weekend I’ll paint and seal it then add some foam to the PVC tubes. Here’s what I managed to put together so far:

Partially Completed Boat Stand

More to come. Tonight I will add Anderson Power Pole connectors to the motor controllers and create a battery harness in preparation for a weekend test drive in the harbor.

Progress in the New Year

Posted on 2013/01/17 by Duck

I’ve started this year off running on all cylinders. While I’ve managed to get a lot done, I haven’t posted any of my progress as of yet. Since I don’t have the time to post all the technical details of each project, I’d like to give an overview of what I’ve been up to.

Project: Media PC

Status: Complete

Overview: I decided to replace my existing media PC which was unable to play HD content streamed from the internet. The bottleneck was not the internet connection but the PC itself. Since I’m not a very patient person, I went to Fry’s and purchased all I needed. This meant compromising on a few things but overall the build was a success. I can now stream HD content and probably even play some video games, though I haven’t had the time to test the latter.

Project: Kitchen PC

Status: Complete

Overview: With the old media PC free to do with it as I pleased, I decided to dedicate it to the kitchen. While most people ridicule me for this upon first hearing about it, it actually has turned out to be a good investment. The original premise was to use the PC along with allrecipes.com for a digital cookbook. It has worked well for this purpose. In addition, this PC has also become a secondary media PC for my girlfriend whenever she cooks and cleans. Yes folks, she spends more time in the kitchen now and I benefit from it… a good investment indeed!

Project: RC Survey Boat

Status: In Progress

Overview: My friend in Portland is still making progress on the hull. It sounds like it is ready for the motors to be installed. On my end, I have put together the boat’s PC and began writing and testing software. I have thus far managed to get code to control servos and a motor controller, communicate via Ethernet and take commands from a joystick. I’m in the process of converting my test code into libraries that I can integrate into one application in order to use a joystick to control the boat via WiFi.

Project: Workshop Setup

Status: 70% Complete

Overview: Since moving in October, I’ve been ever so slowing re-building my workshop. I’ve made upgrades to my CNC, purchased some new tool chests and found a used flammables cabinet on craigslist. I’m in the process of sorting through all the boxes that are still left in the garage since the move, organizing the new toolboxes and refurbishing the flammables cabinet.

Project: FIRST Robotics

Status: In Progress

Overview: In order to give back a little and get kids interested in Engineering, I decided to become a Mentor to High School Students for the FIRST Robotics competition. The competition this year involves scoring Frisbees and climbing a metal pyramid. This video outlines the game play. The students only have 6 weeks to build a competition robot so they’ve got their work cut out for them.

In addition to the above “home” projects, I also have an extended work schedule in effect. I will try to post more details on the projects listed above as I find time.

Survey Boat PC Ordered!

Posted on 2012/12/05 by Duck

Background: This past summer my friend proposed building a remote control survey boat for mapping lakes and reservoirs. He enlisted my help for the electronics. For the prototype he is constructing a hull out of wood and fiberglass. When finished, he will send the hull to me to outfit with motor drivers, sensors, a radio and a controller. The end goal is to make the boat capable of autonomous surveys.

For the controller my plan is to use an off the shelf PC. I researched some possible units prior and settled on a unit Intel was to release soon. Intel termed it the “Next Unit of Computing”. I chose this PC because it is extremely small (4″x4″x1.5″), allows for all the interfaces I’ll need and runs off of 19VDC. This week I noticed the Next Unit of Computing was finally available for purchase so I ordered it along with everything else that it requires. The following is on the way:

Manufacturer	Part Number	Description
Intel	DC3217IYE	Next Unit of Computing (LAN and HDMI)
Intel	6235AN	Wifi / Bluetooth Card
Crucial	CT128M4SSD3	128GB mSATA Solid State Drive
Corsair	CMSO16GX3M2A1333C9	16GB (2x8GB) DDR3 Ram
Anker	AK-93TS19V632-3A	19V @ 6.3A Power Supply
Mini-box.com	OpenUPS	Highly Adjustable UPS. Input 6-34V, Output 6-24V @ 6A. Supports all sorts of battery types

More to come when the components arrive and as I get time.

Rising from the Depths

Posted on 2012/12/01 by Duck

Welcome! I am bringing this site online in hopes of motivating myself to document the many projects I find myself involved in. I have many varied interests but they seem to revolve around water, electronics and science in general. It is my goal to post an update at least once a week documenting any progress or lack there of.

MakaiTronics

Taking Electronics to Sea