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Author Topic: 1/200 scale Bismarck - operating turrets  (Read 1482 times)

Capricorn

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1/200 scale Bismarck - operating turrets
« on: March 02, 2019, 03:38:35 AM »

I've adapted a Trumpeter 1/200 scale Bismarck for RC with rotating turrets, compass directed, it's nearing completion.  I had been trying to encourage someone to do this but no one seems to have done it so I went ahead and got it going.  It's really not that complicated, small stepper motors are used to rotate the turrets controlled by an arduino microprocessor, with input from a simple compass module.  The Bismarck kit is quite well done and easily adaptable to RC.  The hull is plenty large enough for this conversion.


I did a video a while back on the system for the compass controlled turrets:


https://youtu.be/mgtidK7LFhA

Not sure why but most people are convinced that servos should be used, but they are much inferior except for the fact that they only require 3 wires vs 5 for the steppers.


In this particular instance I used premade ULN2003 stepper drivers mainly because they have the plug outlet to plug the stepper connector into.  You can easily make your own stepper driver using the ULN2003 IC.  My main task is to fabricate wiring harnesses to connect the arduino to the stepper drivers.  The program for the arduino is pretty much completed as in the video.


You can also omit the physical director.  It is required in the program but can be omitted from the model which simplifies the installation.  Cap

Seems the photos are too large to insert here, will attempt to reduce them.
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #1 on: March 02, 2019, 03:53:59 AM »

Well compressing photos was not easy enough for me sorry.  500k size limit for files on this forum is a tad outdated.  Will try again tomorrow.  If you want to see the photos they are posted on rcgroups, scale boats, "caps bismarck"
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gingyer

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Re: 1/200 scale Bismarck - operating turrets
« Reply #2 on: March 02, 2019, 10:12:19 AM »

That looks fantastic
Can you give people a guide on how they can copy your system??


I can see me using that if possible in the future
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coch y bonddu

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Re: 1/200 scale Bismarck - operating turrets
« Reply #3 on: March 02, 2019, 12:58:02 PM »

Well compressing photos was not easy enough for me sorry.  500k size limit for files on this forum is a tad outdated.  Will try again tomorrow.  If you want to see the photos they are posted on rcgroups, scale boats, "caps bismarck"




Simply upload to flicker and copy and past the link to share bottom right of picture after uploading and it will compress ready to use on here far far easier than trying to minimise yourself it is FREE to use


Dave
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #4 on: March 02, 2019, 04:03:01 PM »

Thanks Dave, that was easier.  Hopefully this works:


https://www.flickr.com/photos/156669733@N07/with/47257644881/

gingyer, I can post some info.  I'd be happy to see some more similar ships.  Have you used arduino before?  You pretty much have to have a micro processor of some sort and know a little of how to use it.  They aren't really that hard, takes a bit of time, but easy enough.  I have a pdf I had put together with it, I'll clean it up a bit and post it.  Cap
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Colin Bishop

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Re: 1/200 scale Bismarck - operating turrets
« Reply #5 on: March 02, 2019, 04:36:38 PM »

Capricorn,
There is a long running topic on Arduino and its application to controlling gun turrets here:
https://www.modelboatmayhem.co.uk/forum/index.php/topic,56800.0.html
It is currently being applied to the construction of a model of HMS Agincourt by Bob K.
https://www.modelboatmayhem.co.uk/forum/index.php/topic,58070.0.html
Lots of stuff to read but very interesting.
Colin
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #6 on: March 02, 2019, 06:05:47 PM »

I added an "image" of the pdf, 49 inches or so long so scale as needed.


Colin, I've seen the target string, it's nice.  The ship model is great, much better than a styrene kit, but the target system seems stalled. You and c3Po need to push Bob a bit. I've yet to see a compass controlled system like t.a.r.g.e.t. actually operating on an rc model, other than the turntable version in the video I posted.  That is what prompted me to go ahead and do this build.


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C-3PO

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Re: 1/200 scale Bismarck - operating turrets
« Reply #7 on: March 02, 2019, 06:34:51 PM »

Hello Joe,

What a great looking solution you have for Bismarck

The TARGET system stall is mainly my fault as after Mayhem last year (May2018) life got busy for me and I also have many other interests that all grab my time as well as running my own business. Bob was left in a "catch 22" situation as he needed to be able to move the steppers to progress the turret alignment. Bob and I live a distance apart which adds to the complication - indeed I have only met Bob face to face twice.

Bob now has a way to move the steppers and has made quite a lot of progress in the last few weeks.

Just before Mayhem I had a technical issue that I could not work through which meant that even if we had wanted to install the complete TARGET system into Bob's HMS Agincourt I was not confident in allowing it to go live. This issue has now been resolved.

It would be great to see a finalised TARGET system installed in HMS Agincourt - at the end of the day it's a hobby and Bob and I are quite relaxed that we will get there in the end.

I look forward to the updates with your turrets & Bismarck

Regards
C-3PO



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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #8 on: March 02, 2019, 08:46:26 PM »

Hi C3PO, Thanks for the kind words.  I know you all have been working on target for some time.  Actually I recall long ago on this forum conversing with Bob regarding the compass control etc (10 years at least).  So I haven't exactly been a jackrabbit.  I'd just like to see it go, it's been too long.  I think the Agincourt with 7 turrets and some of the other features added in made it cumbersome, just four turrets on the Bismarck is a chore and a half.  I've been constructing wiring harnesses all morning, it will be a rats nest in the hull.  But in the end, yes, no rush, it is a hobby.  I've been sidetracked as well, added a photo to flicker of plaster cast cathedral that is also a 10 year plus project.  Cheers to you and carry on.  Cap
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Colin Bishop

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Re: 1/200 scale Bismarck - operating turrets
« Reply #9 on: March 02, 2019, 10:19:29 PM »

I think the guiding principle was that if it is possible for Agincourt with its 7 turrets then you have a system which is universally applicable. Once the basics have been established then the extra bells and whistles are a logical extension to do 'a proper job'. In that sense it isn't cumbersome but simply taking the principles to their logical conclusion.

Colin
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #10 on: March 03, 2019, 02:38:45 AM »

Hi Colin, Sorry I didn't mean to demean the target system, or Bob's Agincourt.  I just recall, at least the early versions had variable turret rotation speed or response time and other ingenious features but that they impeded progress, maybe should be added after it's operational.  Also just prodding a bit, sometimes a little prodding helps get things moving.  I'd like to see the Agincourt with target on it working, that would be fabulous.  Best, Cap
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Colin Bishop

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Re: 1/200 scale Bismarck - operating turrets
« Reply #11 on: March 03, 2019, 10:15:51 AM »

No problem Cap, I entirely see where you are coming from. The standard project technique is of course to start with the basics and work up from there. As the above posts show, C3PO is approaching it very much as an Arduino project rather than a model boating one and the early experiments opened up all sorts of possibilities in reproducing the co ordinated movements of gun mountings in considerable detail.

That's one of the nice things about hobbies, you never quite know where they are going to take you!

Colin
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #12 on: March 04, 2019, 01:16:37 AM »

Thanks Collin,


I have made progress.  The video link shows the Bismarck main director operating via compass


https://www.youtube.com/watch?v=xlH_yUlGVDs&feature=youtu.be

Once the director works the rest is pretty easy.
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #13 on: March 04, 2019, 06:45:04 PM »

Here it is, functioning turrets and all.  Needs some paint and final assembly, and unfrozen lake.  It's been quite cold and snowy here, no open water foreseen for a month or two. Cheers, Cap


https://www.youtube.com/watch?v=gVJHLP-Y3Po&feature=youtu.be"]https://www.youtube.com/watch?v=gVJHLP-Y3Po&feature=youtu.be
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C-3PO

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Re: 1/200 scale Bismarck - operating turrets
« Reply #14 on: March 04, 2019, 07:25:00 PM »

Joe,

That looks brilliant!

Is the twitching down to varying compass output?

Maybe just my opinion but should the stepper movement be slowed down a little?

Regards

C-3PO
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Colin Bishop

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Re: 1/200 scale Bismarck - operating turrets
« Reply #15 on: March 04, 2019, 07:40:33 PM »

Very impressive on a relatively small model too. As C3PO says, maybe a bit more damping is needed. (but it's easy to criticise!) Great job!

Colin
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C-3PO

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Re: 1/200 scale Bismarck - operating turrets
« Reply #16 on: March 04, 2019, 07:52:59 PM »

Not all electronic compasses are born equal!!

I have used quite a few of them them and have a firm favourite as it just works! and a container of ones that just gather dust along with other rejected hardwares (10 dof's etc)

The compass heading from some of them jump around a fair bit which can soon send the turrets off in one direction only to be commmanded back on target shortly after hence the twitching.

One solution is to use a running/rolling average to introduce some smoothing either your own code or there are libraries that can help.

My favourite compass has a 45 read smoothing buffer onboard so it does not place any processing demand on the main Arduino and gives a pretty good solid heading output into the Arduino.

Another factor that affects the steppers is which software library you use to control them - again some crude and elegant choices exist....

I guess this is the discussion that should happen on the RC & Arduino forum as most Mayhemers eyes will have glazed over by now :)

C-3PO
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #17 on: March 04, 2019, 11:08:34 PM »

Thanks guys, Yes it twitches, more than the mock up.  I'm afraid it was a poor choice for the compass location, under the funnel just above a mass of steppers wires turning on and off, one of the wires is touching the compass module for all I know.  I think I may mount it on the end of a plank and slide it to the far front of the bow as far from the motors and wires as possible, I'm guessing that will help. I'll have to ask you about compass modules C3P0 (on microprocessor forum), I really know nothing of the different types, I have the adafruit LSM303DLHC, main reason being I could make it work.  I did program in a buffer of some sort but I'm not even sure if it's in the present program, will need to check that, I had so many copies and versions of the sketch I'm not sure I have the latest best one.  The stepper library itself is fine, flawless as best I can tell.  Probably should slow down turrets, they were set for the Fletcher, a bit faster ;) .  But the reset of the turrets back to zero is slower than too, I'll experiment. 


The use of the stepper driver modules was a draw, not needed, a lot of extra pieces and wires not needed.  If I did it again I'd go back to the raw ULN2003 on a shield or on it's own homemade PC board, the motors are so small they can practically be driven by the arduino pins alone.  My wife did note all the lights flashing inside she liked that.  Cheers, Cap


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C-3PO

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Re: 1/200 scale Bismarck - operating turrets
« Reply #18 on: March 04, 2019, 11:19:42 PM »

Hi Joe,

I think we have navigated lots of common ground - all I can say to lots of your comments is "Yes I have got that T shirt and the associated grey hairs" :)

Perhaps we can communicate either on the RC Arduino forum, I will PM you my email address.

PS If you are an i2c expert I might bite your hand off - am currently 30-40 hours into a problem that just illudes me - fed up of seeing the reversed question mark character on my serial monitor

Regards

C-3PO _._
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #19 on: March 05, 2019, 12:30:50 AM »

C3P0,  Yes, we've been on this a while, I'm hoping to hang it up with this last build, go on to something else (pc boards with micro bipolars to run the six 150mm?  :o ) .  I'm not an expert in anything really, more of a hack then anything.  Not even sure exactly what i2c is, although I think I've seen it referenced in arduino and am probably using it, I just copy from other working sketches.  You're welcome to send me messages, I'd give it a whirl on my own arduino that's about the only way I can figure stuff out, restart from scratch usually helps too.
Best, Cap
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cgbillb

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Re: 1/200 scale Bismarck - operating turrets
« Reply #20 on: March 15, 2019, 04:49:47 AM »

Good morning Cap
Great built wow I just started my build of the same kit.
Can we email?
Bill
Athens Ga.
ktm30600@gmail.com
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Akira

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Re: 1/200 scale Bismarck - operating turrets
« Reply #21 on: March 16, 2019, 12:19:03 PM »

Cap, Your build is wonderful,Thank you for posting it. I followed it on RCG, but that site seems to have issues.A comment about magnetic fields if I may. Bundles of wires, will create magnetic fields when current flows thru them. I found this on a "big" boat when the compass swung 18 degrees every time the ignition circuit was energized. The manufacturer bundle the ignition and instrument panel wires together and routed them within 6-8" of the magnetic compass. The same effect was found with a flux gate compass when the remote sensor was placed in the same position.
Moved 4-5 feet away(it needed to be away from an iron source as well) cured the problem.You appear to have a lot of potential for this in your hull. Time to reconsider that 1/35 DD! :embarrassed: Jonathan
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #22 on: March 16, 2019, 12:41:02 PM »

Thanks Jonathan, Is RCG stalling, takes forever to load a page?  I've noticed that too, not always just once in a while, I'll post the latest video below.


I'm beginning to think the issue with the compass and motors isn't a magnetic one at least on the compass module itself, could be, makes sense but I think it's current in the wires inducing current in adjacent wires or something.  If I move the compass far from the ship it does the same thing.  I wished I'd twisted the wires together, not sure that would have done it but its a bit late for that now.  We'll see, if I have to I'll program the jumps out, it will make the motion quite a bit less desirable but get rid of the twitching, like have them operate on finite angles, like every 10 deg or something.  Cap
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C-3PO

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Re: 1/200 scale Bismarck - operating turrets
« Reply #23 on: March 16, 2019, 02:19:36 PM »

Hi Cap,
A list of things that come to mind to check/review or that might help
  • Common ground between all components
  • Power source - Are you experiencing voltage drops? - the steppers draw quite a bit of juice - Could you power up the "in boat" install the same way as your "plank" demo to eliminate this possible cause?
  • Seperate power supply for steppers to Arduino
  • Use i2C Bus Pullup resistors ( I WOULD DO THIS FIRST!!!)
  • Introduce smoothing of compass readings
  • Reading the compass to frequently - introduce read every X ms (e.g. 250ms)  rather than every loop
  • Command the stepper update every X ms (e.g. 250ms)  rather than every loop
Clearly a frustrating problem but I am sure you will get there...
Regards
C-3PO
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Capricorn

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Re: 1/200 scale Bismarck - operating turrets
« Reply #24 on: March 16, 2019, 02:28:26 PM »

Thanks C3PO, every suggestion, hint helps.  I will take a look at these.  I guess maybe I need to look at the I2C stuff, it's a bit beyond me but I know there are at least three different ways to read the compass singles into the arduino, maybe one of the other two works better, what compass and method to you use for your compass?  Thanks, Joe


This was from 5 days ago:


https://www.youtube.com/watch?v=1r29gPFgS1M
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