Compass controlled gun director and turrets - RC Groups
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Sep 10, 2017, 09:52 AM
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Compass controlled gun director and turrets

For those of you interested in naval ships with gun turrets, and animating them, I have recently worked through a method that works pretty well and probably can be adapted to most RC model ships. Many of you will recognize the turrets in the video, the lindburg BD 1:125 kit (the director is balsa). I don't necessarily imply this can work on a boat that small, I only used the pieces because I could scavange them, it's really meant for a BB or similar ship with 2 forward and 2 aft turrets (but can be easily modified).

The compass module is an LSM303, with an arduino uno processor. The motors are 28BYJ-48 steppers and are switched using ULN2003 and ULN2803 arrays (switches). They run on 5-6v, in the video they run on the laptop usb power, but battery works fine.

The basic operation is simple, when activated the gun director takes the current compass heading and holds it as the ship turns. The turrets all respond to the director heading and turn to match the director heading. When the heading is out of the turrets field they turn ahead or astern. Only a single channel is required to activate the system, at that point it works autonomously.

Obviously once one has a compass on board there are many other functions that can be added.

Although not currently afloat (as always with me), I know there are some out there that are able to float this. Join us at the homebrew hacks page of this forum. Regards, Cap

compassdirector with 4 turrets (3 min 17 sec)
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Sep 10, 2017, 10:31 AM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
I really like it.

Will you be able to adjust the gun director using RC to change the targeting?

Sep 10, 2017, 12:31 PM
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Gravman's Avatar
How cool is that!
Sep 10, 2017, 01:44 PM
Registered User
Umi, Sure, depending on the input, it's currently set so it latches on to the first compass reading when activated and points dead ahead. It can be set to go 90 degrees off that reading or anything else 0-360. My sort of theorectical application is that it's set to go 90 degrees starboard of the heading, so you steam the ship out, turn broadside to the "target" and acitivate it, then are free to steam around and it keeps the original target heading. It makes sense to have it set for the current heading though, so you steer toward the target, activate, and from then on it is trained on the target.

It's certainly possible to input a deflection from the current heading from a radio transmitter, using standard radio joystick it's going to be pretty approximate just due to the range covered. A slight hack to the radio and you can likely accomplish an accurate pointer with a multiturn pot or rotary encoder.

Gravman, you too can have one. The motors are $4 or less, $10 for an uno and another few bucks for the chips and wires. Hope you like a lot of wires.

Of course a similar system using servos is workable, with fewer wires. But, to date, I've not been able to do get there to my satisfaction, the limitation of the servo range is very restrictive, especially for the director. With stepper motors there is no rotation limitation Decent servos, especially if they have larger rotation ranges are quite expensive, these motors cost only $4 and add the cost of the processor, and it's still less than the cost of a single good servo.

So, for anyone who might want to animate their turrets I'm glad to lend a hand, would be great to see it in action asea rather than tabletop. Cap
Sep 11, 2017, 07:42 PM
Webmaster, MMCNE
RCBoater's Avatar
I started playing with an Arduino a couplke of months ago-- the more I play with it, the more possibilities I see for using it in a model, and around the house!
Sep 11, 2017, 09:18 PM
Registered User
Hi RCBoater, many possiblities. I've got two running full time at my house. One runs the chicken coop, the other runs the greenhouse. The chicken coop has been running a couple years now, same uno, works flawless. Only problem was a mouse chewed the powersupply wires, low end voltage, lucky for mouse. Runs the coop door, heater (winter) fans (summer). The greenhouse only waters the tomatoes twice a day at this point, but works great, it's only 8' sq and very full so the auto watering is nice, I only have to fight though the foliage to pick the tomatoes. Cap

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