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Author Topic: T.A.R.G.E.T - Rotating Seven gun turrets?  (Read 22412 times)

raflaunches

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #300 on: April 08, 2017, 01:30:11 PM »

Hi C-3PO


I think that sounds right as 1/8" of an inch equals 12inches in 1/96 scale :-))
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #301 on: April 08, 2017, 01:40:46 PM »

Hi Nick,

Thanks for the confirmation - I need to be more creative to get the size down of the goodies I am working on...
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Bob K

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #302 on: April 08, 2017, 01:58:10 PM »

Just picked up on your question C-3PO.   yes 1/8 inch at 1/96 scale.
At a pinch I could go up to 4 mm by having thinner barrels.  What do you have in mind?
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #303 on: April 08, 2017, 03:48:00 PM »

Hi Bob,

Keeping my matches dry for now but I do have one more question.

It looks from the crude measurement I made below that in this image the diameter of the gun barrel looks approx twice that of the calibre.

So 12" calibre approximates to about 24" diameter barrel - is my logic sound? and at scale OD of barrel approx 1/4inch?

Please note the screen ruler is using centimetres just because it was easy as the 8 cm mark aligned nicely ...

Thank you for your help

C-3PO
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Bob K

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #304 on: April 08, 2017, 04:35:36 PM »

Sorry C-3PO, I am stumped on that one.  Outside diameter does vary along the length though. 
At the muzzle 2 x i/Dia sounds about right

I always thought a gun of 12 inches was a measurement taken from the Shipwrights model, as to how much of it stuck out of the turret?   %%
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Colin Bishop

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #305 on: April 08, 2017, 05:35:37 PM »

Check out this link - it has a constructional drawing of a 12 inch gun of approx the right vintage:

https://commons.wikimedia.org/wiki/File:BL_12_inch_Mk_VIII_gun_diagram_Brasseys_1899.jpg

Click on the gun image for a larger view.

Colin
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #306 on: April 08, 2017, 10:28:06 PM »

Most British guns, and those inspired by our guns had a bell muzzle which neatly curved out of the taper gently to the muzzle. Other nations either had the taper straight to the muzzle or had a squared collar which looks awful in my opinion.
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #307 on: May 12, 2017, 02:29:10 PM »

I may be joining this debate a little last so apologies if this idea has already been suggested. On my Iron Duke I have five turrets and I linked all the aft facing ones together using mono filament fishing line as each sits on a drum. The drums are then winched round using a servo sized drum sail winch. The same for the forward turrets with a separate winch. With modern radio equipment you can control both the speed of rotation and the throw at each side. I control both groups separately (I have potentiometer pots to use on my system). Because the pull is on the circumference of each turret rotation is very smooth.


With Agincourt you could do the same which would mean all the forward facing turrets could turn to any position you want and if abaft the beam the aft turrets could be controlled to point in the same direction.


Absolute parallelism isn't needed on the pond because at any distance you just can't see that accurately. Because the groups are separately controlled I can fine adjust them for the centre line. I think an Arduino based system is probably the gold standard but this system works well enough and is easy to construct and maintain.


Hope this may be of help


Cheers


Geoff
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #308 on: May 13, 2017, 11:18:33 AM »

Hi Geoff,

The thread developed from the basic moving of turrets to something more ( see the detail in the posts) - Lots of "whistles and bells" functionality was added to the basic movement solution which perhaps pushed it in the direction of what might be considered the gold standard.

The movement of turrets only using stepper motors controlled with an Adruino compared to your solution would be comparing apples with apples

So I would suggest that the Arduino/stepper route is a quick and easy way to achieve the outcome without investing time and effort in R&D and fine tuning of the engineered solution to get it to do what you want.

In my simple world placing 7 steppers motors into holes cut in the deck, ( very similar to mounting 7 servos) supplying each with power and a data signal , plugging these into an Arduino which in turn is connected to the receiver seems more simple than to devise and install a turret mount and pulley system and all that entails to control multiple turrets.

I think the stepper motor route is like a "pre-made solution" and you just install components and connect them together where as your route is the "Scratch Build" route which for many of us is the more challenging route as in essence you start with a blank piece of paper and have to go through the same learning curve you experienced with any "funnies" to iron them out - How create a mount, , pullies, cord,  what amount of friction vs. slippage etc

Just my 2 pence worth - the good thing is  people have a choice and should they wish to "move their turrets" could use either of of the 2 routes or make their own hybrid - they simply have to choose which they think is easier to construct and the functionality they desire.

To enable others to use the stepper route if they want to - it is the intention to publish a "How to guide" at some point in the future which would detail all that's involved, the code , the components and you simply choose what functionality you want from basic movement of a turret through to target tracking, synchronised sound/light/smoke/gun recoil

Bob's HMS Agincourt build thread will give more detail as things progress - http://www.modelboatmayhem.co.uk/forum/index.php/topic,58070.msg605416.html#msg605416

Regards
C-3PO
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #309 on: October 17, 2017, 10:23:16 AM »

Update - as the season's change more time indoors to play boat bits...

Behind the scenes things have been ticking over slowly.

To make this solution work for Bob K’s HMS Agincourt ( “ a boat of 2 halves”) a method was needed to communicate with the turrets in each half of the hull.

Bob was certain that he did not want any cable connections between each part of the hull so another solution was needed.

So a re-think of how this could be achieved has yielded some significant, initially unforeseen benefits to the whole solution…

Rather than having one Arduino with loads of pin connections (Ardunio Mega 2560) a more simple route has been adopted using one Arduino Uno as a Master Controller and the very small Ardunio Nanos (Approx £3 each), one for each “Turret Control Unit”

The “Master” controller reads the RC Receiver signals and the Compass sensor and then sends commands along with the Turret Heading to each “Turret Control Unit” wirelessly on 459Mhz

This does away with the cable looms running up and down inside the hull as each “Turret Control Unit” simply needs a 2 wire power supply connection.

The added benefit for this system architecture is that we now have a local processor at each turret that can be used to implement “Auto Alignment” of the stepper motors at system startup. Using an IR sensor for alignment, an accuracy of 1 degree can be achieved. It would also be possible for the IR sensor to act as a watchdog to limit the turret movement to a predefined range.

So each “Turret Control Unit” is made up of – Arduino Nano / Stepper motor and control board / 459mhz Radio Transceiver / Relay for triggering smoke generator / LED control for gun flash

Regards
C-3PO
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Bob K

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #310 on: October 17, 2017, 11:40:39 AM »

Many thanks C-3PO.  It might sound more complicated, but having a universal sub-assembly for each turret actually makes interconnection wiring vastly simpler.  Each 'local' electronics unit can be individually customised to suit physical bearing angle ranges etc (I think).

Meanwhile the 7 foot ship is coming along.  Just fitted the four motors shafts and "A" frames.
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #311 on: October 17, 2017, 06:54:28 PM »

The added benefit for this system architecture is that we now have a local processor at each turret that can be used to implement “Auto Alignment” of the stepper motors at system startup. Using an IR sensor for alignment, an accuracy of 1 degree can be achieved. It would also be possible for the IR sensor to act as a watchdog to limit the turret movement to a predefined range.


Now that's a good idea. I'm currently using the thirty seconds of 'compass output settling time' after start-up to run through a manual turret alignment sequence. (But I'd sooner watch turrets sort themselves out!)

Andy
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #312 on: October 21, 2017, 05:41:39 PM »

I have been playing with creating an "Auto Align" sequence for the little stepper motors.

The current thinking is to use an IR sensor to achieve the alignment. The IR Sensor has the "IR Source" and "IR Sensor" facing each other and the Arduino can sense if the IR beam is broken/made by reading the sensor.

My jaw has dropped a little as I didn't expect is to be so accurate. My latest test is using a scalpel blade cut as the "slot" that allows the IR source to pass through to the sensor. I guess due to the very small wavelength of the IR  the slot appears to be a mile wide!

For test purpose a slot cut in a piece of stiff paper is fine - but can anybody suggest how to source/create a very small slot in a more durable material for use in a model boat. For size comparison you can only just see light through the paper cut I am using now when held up to a bright light source.

Thanks in advance for any suggestions

Regards
C-3PO
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #313 on: October 21, 2017, 08:15:33 PM »

If I am imagining correctly the IR unit as a "U" shaped slot in a block, then the beam probably has a relatively large diameter.  Maybe 3 mm ?  Any way to reduce this with a mask so the beam is smaller?
Alternatively instead of a cut would some stretched fuse wire over a slot provide a trigger point?
Or very thin brass, photo-etched?  ie:  A section of steps (flat) and just opening one tread by a few degrees.

Just some thoughts.

Bob K
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #314 on: October 22, 2017, 09:53:41 AM »

Hi Bob,

Fascinating little device. The sensor already has a slot - just over 1 mm wide. It doesn't seem to use the whole slot just the part highlighted with the red line.

The sensor trigger can be made by either making or breaking the beam.

I have changed my approach a little as I want the implementation to be simple and reproducible with out much tinkering.

Current logic is to have a wider slot window on the component that passes through the sensor and capture the stepper motor step that the sensor is "triggered on" and the same when "triggered off" and compute a mid way between these 2 positions as the alignment "step".

I also have some Hall effect sensors on order as well as some very small magnets to see if this approach has any merits ( Magnets -  5MM X 2MM ,3MM X 2MM , 2MM X 1MM )

C-3PO
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #315 on: October 25, 2017, 11:30:32 PM »

Well having gone down a few dead ends I now have a working solution for aligning stepper motors as they are powered on.

Unlike servos they have no inbuilt position feedback mechanism (internal pot)

The accuracy is stunning - certainly less than 1 degree

Just a little bit of code to write and the process will be automated.

I will post a video once it's completely finished.

C-3PO
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #316 on: November 01, 2017, 09:21:51 PM »

Video showing stepper motor auto alignment.  Each cycle the power is reset and at start-up we have no idea of the relative stepper motor position.

Interesting experiment... Youtube video link https://youtu.be/e1lEdoixKfI

C-3PO




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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #317 on: November 01, 2017, 11:21:17 PM »

VERY neat.  :-))  I'm guessing that accuracy with Hall effect sensors won't be nearly so precise - but those would be good with tasks such a multiple revolution counts (winches, propshafts, etc.)


Andy
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #318 on: November 02, 2017, 01:14:51 AM »

Impressive  :-))  It looks like you have solved the start up position issue. 
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #319 on: November 02, 2017, 05:03:21 PM »

Hi Andy,

I think the sensor would work very well for 
Quote
but those would be good with tasks such a multiple revolution counts (winches, propshafts, etc.)

Another application for the little beast - https://www.youtube.com/watch?v=cxpSbWlj8FQ

The solution uses one of these - TCRT5000-INFRA-RED-SENSOR – simply point at the surface at a distance of 15mm'ish

No driver required – simple 3 pin connection – even got an LED on the board that indicates sensor triggered so you can play around with it to see how it senses without the Arduino.

I am using black and white electrical tape as the surface that the sensor looks at – really simple stuff….

It took me a little time to get my head around why I got different trigger points depending on direction of travel. My conclusion it that as the emitter is to one side of the sensor and the receiver the other in relation to the direction of travel – so I guess it’s no surprise that for the emitter to shine it’s thing where the surface changes colour (black to white or white to black trigger point) they will be different depending on direction of travel.

The above explains why you see my alignment sweeps backwards and forwards

The trigger line is monitored by the Arduino using a “hardware interrupt”

Available from here - https://www.ebay.co.uk/itm/2x-TCRT5000-INFRA-RED-SENSOR-LINE-TRACKER-FOLLOWER-ROBOTS-ARDUINO-PI-UK/272910818377?hash=item3f8ac09c49:g:ukAAAOSw44BYmNFl



C-3PO
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #320 on: November 30, 2017, 05:08:38 PM »

Smokin...

My version of smoke generation - basics working - now need to refine it and make it useful

https://www.youtube.com/watch?v=i43oJEIi6hY




C-3PO
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bfgstew

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #321 on: December 01, 2017, 10:09:42 AM »

I have not read the whole thread so I apologise in advance if I go over old ground.
My dealings with steppers and micros (picaxe) is fairly good and have some very good, accurate results with a camera macro stack driver and cnc router. The main point being is counting, as long as it is told to count each step it can go back to the exact same start point every time, no need for IR sensors or any other added input devices, which can cause errors, it can all be done with coding.
Sorry if trying to teach granny to suck eggs.


Stewart
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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #322 on: December 01, 2017, 10:53:13 AM »

Hi Stewart,

I love eggs :)

The issue is simply that the stepper mounted in a model boat, powered by batteries ( that go flat!), interfaced to RC kit, no clever system to keep the power on while steppers automatically return to home as the user removes the power, shoved in and out the back of a car is going to lead to the stepper ( or the turret mounted to the stepper with fit that allows some rotation! covered else where in thread ) not being in it's known "Home" position at some point when you power up the system.

This was clearly not an acceptable situation.

So obvious route was to have a manual alignment process/confirmation at power on to confirm steppers (turrets) in known "Home" position to prevent the possibility of gun turrets rotating into parts of the superstructure. One option was to have a slip friction fit of the turrets so you simply rotated them on the stationary stepper to align them - bingo..

All this lead onto a way of automating the process - the IR sensor.

Agree 100% - in the ideal world if all the steppers where located in "home" position at power up none of this waffle would be required... but what do you do if they are not?

C-3PO
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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #323 on: December 01, 2017, 11:13:18 AM »

C3PO...........i agree in principle with your dilema and it is frustrating that making things fool proof is somewhat tiresome (not saying you are a fool by a long stretch), and raises more complications than it solves, (been there, done it).
My macro stack unit, i can get it to do any amount of steps in any amount of configurations, press home button it goes back to its home position. Powered off a 12v wallwart power supply. Same with my cnc, always goes back to home. Now as long as the units are not disturbed everthing is hunky dory. This is the problem. Then, what I would do would be to have 2 sets of reed switches set at either end of travel, on start up/power on, simple routine to run each turret to one switch then opposite direction to the other, counting steps as it goes, divide the longest travel, divide by 2 and that will be home. Use very small magnetic reed switches rather than opto switches as water can play havoc with opto stuff.
Again i apologise if this has been covered, when i get time i will go through the whold thread as this is very interesting.

Stewart


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C-3PO

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Re: T.A.R.G.E.T - Rotating Seven gun turrets?
« Reply #324 on: December 01, 2017, 11:40:25 AM »

Hi Stewart,

No apologies needed - if there is a way to enhance this then I am all for it....

My own experience of micro reed switches is I got varying trigger points so I discarded this as an option for this project. Maybe the quality of the components/magnets etc where not good ( or more likely the implementation by the user (me) was suspect)  - I may well revisit this.

Points noted re the water - chances are if the sensors are wet then so is a lot of other electronics!

I guess this is one for Bob to consider as I am just playing with this topic - the Mug Mayhemer who is likely to install it for it's maiden outing is Bob K in his magnificent HMS Agnincourt build.

I am currently focusing on producing lots of smoke on demand for 14 guns in 7 turrets from one central smoke unit not using 12v SLA's

All part of the fun...

C-3PO
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