01-24-2009, 09:01 PM
A few people have seen me on the lake and wonder what I’ve got running on my boat. I figure that this might interest you guys. It’s just a showing of what I’ve created. Please let me know if you have any suggestions.
First, the boat hull itself is a simple flat bottom hard chine skiff made from ½” plywood, glue, screws, and paint. =) The whole deal weighs in around 150 lbs and I’ve got pneumatic wheels on the back so I can launch it from my truck solo. It will carry me and a fishing partner with about a 5” draft so this can get into the really tight stuff. I can’t wait for summer so I can get her into Haymeadow and Eagle Valley.
![[Image: greenfrog003kk0.jpg]](http://img177.imageshack.us/img177/6879/greenfrog003kk0.jpg)
[#000000][font "Arial"][size 2](That's the NDOW boat number for "homemade" boats. I registered it because its "motorized". I didn't want a ticket from Mr. Warden.)[/size][/font][/#000000]
Now, the really cool part: the drive system. I put two Minnkota Endura 30 trolling motors on the sides. These things are really cheap but are only tiller controlled and transom mount. The motors then connect into a home built dual H-Bridge PWM controller. This lets me vary the power of each motor without using energy wasting speed coils. I designed it with high resolution of 1023 speeds forward and 1023 speeds reverse. The board itself can handle 30V and around 80 amps of current for each motor, so the little 30lb motors that pull 60 amps combined are barley working it.
![[Image: january19008zt8.jpg]](http://img294.imageshack.us/img294/9333/january19008zt8.jpg)
![[Image: january19006ds6.jpg]](http://img502.imageshack.us/img502/7589/january19006ds6.jpg)
[#000000][font "Arial"][size 2](The heat sinks, processor, and other workings are underneath the board. The little pigtail is my programming header, and the other little board with the multi colored wirring is where the Wii and computer plug in.)[/size][/font][/#000000]
On the same board lies the embedded micro controller (MCU) that controls the motors. The first incarnation had an interface for a PC Analog Joystick and that worked pretty well. But I decided to step up the geek factor and have since added a Nintendo Wii Nunchuck interface to it as well!
![[Image: january19003vw7.jpg]](http://img502.imageshack.us/img502/5013/january19003vw7.jpg)
[#000000][font "Arial"][size 2](A custom Wii Nunchuck adapter so that I didn't get in trouble with the family for destroying a precious Wii accessory!)[/size][/font][/#000000]
It has two standalone modes of operation. The first being a direct control method, this is like a video game. Move the joystick left and right and the boat spins left or right. The motors work in a skid steer fashion, like a bobcat. It’s the same thing with forward and back. When I first got this working and tried it out I was surprised about how responsive and fun it was to pilot. I always found that a foot pedal trolling motor seemed cumbersome; I always overshot it or fumbled with the speed control. This way, I have a very nimble craft.
The second mode is trolling mode. Here forward/back joystick motion increments the motor speed so I don’t have to keep the joystick pressed. The biggest drawback to this is the tracking of the craft with wind, waves, and external forces; the drag of a lure(s) and big fish fighting causes torque that pulls the boat left or right.
That’s were the next mode, auto troll, comes in. Here the microcontroller accepts commands from a serial device, my laptop, and passes the joystick input forward. Now, the laptop has a USB GPS device so I can read the location, speed, and heading of the boat in real time. Using this I wrote software that parses the GPS sentences and extracts the data. Then using a digital Proportional Integral Derivative servo algorithm it determines witch way and how hard to steer the boat to keep it on track. It also does the same thing with the boat speed so I can keep that constant as well.
Since the boat controller is passing on the joystick readings I can still use the joystick to change my set heading left or right and speed up or down. Then my laptop sends commands to the boat controller setting the fwd/rev and power of each trolling motor.
![[Image: january19001pt2.jpg]](http://img443.imageshack.us/img443/3658/january19001pt2.jpg)
[#000000][font "Arial"][size 2](Nothing like a long night of debugging emdbedded systems)[/size][/font][/#000000]
![[Image: january19010kx2.jpg]](http://img520.imageshack.us/img520/7557/january19010kx2.jpg)
The whole thing is powered by two Group 27 deep cycle batteries wired in parallel. This gives me a good 6 hour run time while pulling 15-20 amps and still leaving my batteries at or above 50% power. I measure the amp draw using a simple shunt made from a 7.5” long piece of 12GA solid copper wire, it will drop 1mv per amp and I measure it will a little DVM. At this current consumption the boat moves about 1.4 – 2.0 knots. Not that great. The next boat I build will have a more efficient hull design.
Coming up, I have started to write an autopilot program!
[signature]
First, the boat hull itself is a simple flat bottom hard chine skiff made from ½” plywood, glue, screws, and paint. =) The whole deal weighs in around 150 lbs and I’ve got pneumatic wheels on the back so I can launch it from my truck solo. It will carry me and a fishing partner with about a 5” draft so this can get into the really tight stuff. I can’t wait for summer so I can get her into Haymeadow and Eagle Valley.
[#000000][font "Arial"][size 2](That's the NDOW boat number for "homemade" boats. I registered it because its "motorized". I didn't want a ticket from Mr. Warden.)[/size][/font][/#000000]Now, the really cool part: the drive system. I put two Minnkota Endura 30 trolling motors on the sides. These things are really cheap but are only tiller controlled and transom mount. The motors then connect into a home built dual H-Bridge PWM controller. This lets me vary the power of each motor without using energy wasting speed coils. I designed it with high resolution of 1023 speeds forward and 1023 speeds reverse. The board itself can handle 30V and around 80 amps of current for each motor, so the little 30lb motors that pull 60 amps combined are barley working it.
[#000000][font "Arial"][size 2](The heat sinks, processor, and other workings are underneath the board. The little pigtail is my programming header, and the other little board with the multi colored wirring is where the Wii and computer plug in.)[/size][/font][/#000000]On the same board lies the embedded micro controller (MCU) that controls the motors. The first incarnation had an interface for a PC Analog Joystick and that worked pretty well. But I decided to step up the geek factor and have since added a Nintendo Wii Nunchuck interface to it as well!
[#000000][font "Arial"][size 2](A custom Wii Nunchuck adapter so that I didn't get in trouble with the family for destroying a precious Wii accessory!)[/size][/font][/#000000]It has two standalone modes of operation. The first being a direct control method, this is like a video game. Move the joystick left and right and the boat spins left or right. The motors work in a skid steer fashion, like a bobcat. It’s the same thing with forward and back. When I first got this working and tried it out I was surprised about how responsive and fun it was to pilot. I always found that a foot pedal trolling motor seemed cumbersome; I always overshot it or fumbled with the speed control. This way, I have a very nimble craft.
The second mode is trolling mode. Here forward/back joystick motion increments the motor speed so I don’t have to keep the joystick pressed. The biggest drawback to this is the tracking of the craft with wind, waves, and external forces; the drag of a lure(s) and big fish fighting causes torque that pulls the boat left or right.
That’s were the next mode, auto troll, comes in. Here the microcontroller accepts commands from a serial device, my laptop, and passes the joystick input forward. Now, the laptop has a USB GPS device so I can read the location, speed, and heading of the boat in real time. Using this I wrote software that parses the GPS sentences and extracts the data. Then using a digital Proportional Integral Derivative servo algorithm it determines witch way and how hard to steer the boat to keep it on track. It also does the same thing with the boat speed so I can keep that constant as well.
Since the boat controller is passing on the joystick readings I can still use the joystick to change my set heading left or right and speed up or down. Then my laptop sends commands to the boat controller setting the fwd/rev and power of each trolling motor.
[#000000][font "Arial"][size 2](Nothing like a long night of debugging emdbedded systems)[/size][/font][/#000000] The whole thing is powered by two Group 27 deep cycle batteries wired in parallel. This gives me a good 6 hour run time while pulling 15-20 amps and still leaving my batteries at or above 50% power. I measure the amp draw using a simple shunt made from a 7.5” long piece of 12GA solid copper wire, it will drop 1mv per amp and I measure it will a little DVM. At this current consumption the boat moves about 1.4 – 2.0 knots. Not that great. The next boat I build will have a more efficient hull design.
Coming up, I have started to write an autopilot program!
[signature]
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