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Author Topic: Automating boat movment  (Read 644 times)

Skimmer Fan

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Automating boat movment
« on: October 13, 2019, 08:47:39 PM »


Has anybody had any experience or ideas of how you would get a boat to follow a set route without remote control.
The model world has a system of letting a wire into a base board and the model cars busses follow the wire using a magnate. The vehicle is permanently energized so just keeps on following the wire.
Show tank would be about 4ft x 2ft.
Boat probably 1/72
Hope you understand what I am asking.
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Skimmer Fan

TheLongBuild

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Re: Automating boat movment
« Reply #1 on: October 13, 2019, 09:02:04 PM »

Raspberry pi might be able to do something like that, although the last example I heard was the sailing boat went the wrong way up the river.. %%

Capt Podge

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Re: Automating boat movment
« Reply #2 on: October 13, 2019, 09:07:28 PM »

My initial thoughts are towards what, in real life, would be some sort of auto-pilot. Not sure how you would achieve that but guessing at GPS with way points programmed in.


Regards,
Ray.
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Colin Bishop

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Re: Automating boat movment
« Reply #3 on: October 13, 2019, 09:32:45 PM »

What you are describing is similar to the animated ice skating rinks on Christmas decorations. It requires close magnetic proximity which would be difficult if not impossible in a water tank.

If you have a GPS system which could set waypoints in a 4x2 tank then the US Military would be beating a path to your door!
 
You might be able to build an electronic circuit with an optical sensor which steers the boat away from the tank sides so it circulates around the tank.

Colin
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Capt Podge

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Re: Automating boat movment
« Reply #4 on: October 13, 2019, 09:57:40 PM »

OK then - how about 'over the tank' (overhead) wires, running on battery power only for safety, with wires fore and aft,  from the ship's masts or other upperworks location - bit like the dodgem cars.


Just trying to keep it relatively simple...


Regards,
Ray.
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frogman3

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Re: Automating boat movment
« Reply #5 on: October 13, 2019, 10:10:19 PM »


HI well I don't know if anybody eles has had one of these revel blue devil destroyer model kits but In that it had a idea of the ship goin to a set course by a plastic disk that is turns slowly by the motor gearbox an the disk could be changed with others of a different shape to move the rudders on the ship eg. one disk for a complete circle another to do a figure of eight an another for just straight running if I rember rightly there was about 5 different disks
chris
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jaymac

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Re: Automating boat movment
« Reply #6 on: October 13, 2019, 10:15:44 PM »

Albeit not  simple but drones can do it might pay to look on their forums
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Colin Bishop

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Re: Automating boat movment
« Reply #7 on: October 13, 2019, 10:18:26 PM »

Yes, I have heard of such systems but I don't think they would work too well in a 4x2 tank. The original poster clearly needs pretty precise positioning and that only comes if there there is a close magnetic connection between the moving element (boat) and the fixed path (wire).

Maybe there could be a wire buried in the bottom of the tank and each boat would have a stiff vertical wire with a magnet on the end which skims the bottom of the tank?

Even then it all seems a bit complicated.

Perhaps the OP could explain exactly what he is trying to do and why?

Colin
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Colin Bishop

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Re: Automating boat movment
« Reply #8 on: October 13, 2019, 10:19:47 PM »

Quote
Albeit not  simple but drones can do it might pay to look on their forums

In a 4x2 tank? That's smaller than a bath!

Colin
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C-3PO

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Re: Automating boat movment
« Reply #9 on: October 13, 2019, 11:33:55 PM »

Route out the desired path of travel in a sheet of Perspex.

Mount the Perspex 'x' inches below the surface of the water.

Attach a guide pin (dowel) to the underneath of the boat and locate the guide pin in the Perspex path

Well it sounds plausible :)

C-3PO
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Capt Podge

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Re: Automating boat movment
« Reply #10 on: October 13, 2019, 11:39:33 PM »

Arduino Boards - is it at all possible to programme these boards to follow a specific step by step route (ie rudder movement /motor speed)  and set to repeat the sequences?


... and before I get shot down with curt remarks - no, I have absolutely no idea about the capabilities of the Arduino system!


Just as a matter of interest - what dimensions of vessel is being proposed here...
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C-3PO

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Re: Automating boat movment
« Reply #11 on: October 13, 2019, 11:57:15 PM »

Arduino Boards - is it at all possible to programme these boards to follow a specific step by step route (ie rudder movement /motor speed)  and set to repeat the sequences?


... and before I get shot down with curt remarks - no, I have absolutely no idea about the capabilities of the Arduino system!


Just as a matter of interest - what dimensions of vessel is being proposed here...

Yes to Arduino can do the first bit (repeat specific steps over time - rudder/motor speed etc) but the position of the boat will need "correcting" to follow the path.

GPS is a no no - accurate to 5M if you are lucky - and tracking to a waypoint without bow/stern thrusters would be a challenge - and with them an even bigger challenge to write the PID to control the positioning corrections

Ultrasonic sensing might help a bit - you could work out how far you where from an obstacle - but would not necessarily be able to identify which object hence position

You could use "TOF" laser sensors - very accurate distance measurment but again you would still not know position

You could use some IR sensors slung under the boat tracking near the bottom of the pool to follow a black path line - but once you have lost the line unlike a robot you can't stop/pause movement immediatley whilst you re locate the line as the boats momentum will allow the boat to drift off the line

https://youtu.be/bxXyhgX3Sws?t=86

You could use 2 NEMA stepper motors,  connect to extended spindles that are located in the water to control X/Y wires on pulleys to pull the boat around - a bit like a "2D plotter" - the Arduino could control the steppers to accurately position the boat on a repeatable path

https://www.youtube.com/watch?v=gTH3VjvCfpA

C-3PO
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Capt Podge

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Re: Automating boat movment
« Reply #12 on: October 14, 2019, 12:12:46 AM »

Now, that is a most informative reply and helps a great deal in attempting to understand the complexity of the programming involved.
I thank you sincerely for this.


Now is a good time for me to go away and ponder over the complexities of achieving a satisfactory answer to the originators question.   :-))


Regards,
Ray.
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Colin Bishop

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Re: Automating boat movment
« Reply #13 on: October 14, 2019, 09:22:27 AM »

Sorry if I seemed to be curt but going back to the original post, the system described as usd in model displays appears to be a simple wire and magnet setup. I would think he is looking for something similar in a small tank. In which case complex electronics in craft small enough to toddle around in the average bathtub seems to be to be overcomplex engineering!

I like C3PO's idea of a transparent sheet mounted just below the surface which would be all but invisible. Building on that idea why not try using an acrylic glazing sheet (available from DiY stores) and attach an unobtrusive wire to it. The the floating craft, whatever they are, could have neodymium button magnets mounted on ther bottoms or on an extended keel if you want to keep the acrylic sheet deeper in the water. Effectively this would be the equivalant system to what he is describing in his post.

Cheap and cheerful if it works.

Colin
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warspite

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Re: Automating boat movment
« Reply #14 on: October 14, 2019, 09:29:09 AM »

OK then - how about 'over the tank' (overhead) wires, running on battery power only for safety, with wires fore and aft,  from the ship's masts or other upperworks location - bit like the dodgem cars.


Just trying to keep it relatively simple...


Regards,
Ray.


or the opposite, the runner is under water and the boat is connected to the runner by a wire that guides the bow whilst the prop pushes it along, the wire is off the floor of the tank held to the sides by wire supports that bend down onto the runner, the wire from the boat goes under the wire and loops up in a definite U shape that does not touch the supports. This way of looping the wire to the runner ensures they do not become detached due to wave action, and yes 4 x 2 feet is very small, more of a fish tank than a display case.
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warspite

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Re: Automating boat movment
« Reply #15 on: October 14, 2019, 09:30:59 AM »

Or as Colin suggests, more of a scaletric slot system in clear acrylic
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TailUK

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Re: Automating boat movment
« Reply #16 on: October 14, 2019, 09:43:08 AM »

You could try something like this.  It's like a bike chain but in plastic so it's waterproof. It runs around pulleys and guides and drags things around using magnets.

https://www.magnorail.com/en
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malcolmfrary

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Re: Automating boat movment
« Reply #17 on: October 14, 2019, 09:58:49 AM »

HI well I don't know if anybody eles has had one of these revel blue devil destroyer model kits but In that it had a idea of the ship goin to a set course by a plastic disk that is turns slowly by the motor gearbox an the disk could be changed with others of a different shape to move the rudders on the ship eg. one disk for a complete circle another to do a figure of eight an another for just straight running if I rember rightly there was about 5 different disks
chris
The results of the Blue Devil self steering in real life were always subject to the accuracy of the build and weather on the day.  Anybody who remembers non radio sailing will be familiar with the concept that a free running boat, if it doesn't actually go straight, will do a spiral course.  Or a semi circle hitting the launch bank a bit further along.
This 4 by 2 tank, are we talking feet, yards, metres?  What size of boat?
A slot system needs a deep enough slot or a guide system to cater for lumpy water.
The best idea so far is the clear plastic sheet with a heavy steel wire describing the course and a magnet to keep the boat over the wire.  Maybe a magnet each end, maybe a front magnet on a swivelling arm linked to the steering.  Thinking back a long way, there was a trolley bus system that derived its steering from its overhead pick-up. It handled curves and corners great, but having finished with a corner, was incapable of going straight.  To make the constant steering corrections look reasonable, the trick was to park other vehicles strategically for it to "steer round".  Eheim strikes a chord.
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Capt Podge

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Re: Automating boat movment
« Reply #18 on: October 14, 2019, 10:17:42 AM »

Really enjoyed those last 3 videos - really eye catching and thought provoking.


That's it, I'm off to the shed, to bury me head  %%
(and watch them all again)


Regards,
Ray.
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warspite

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Re: Automating boat movment
« Reply #19 on: October 14, 2019, 10:26:39 AM »

plastic rod does come in lengths of 200+ for certain sea states  {-) so would easily accomodate the slot system, rudder set to push against the outside, original poster said 4 ft (1220 mm) x 2 ft (609mm).
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Skimmer Fan

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Re: Automating boat movment
« Reply #20 on: October 14, 2019, 11:55:09 AM »


A big thank you to all.
I realise 4ft x2ft is quite small but it is only meant to be a prototype to see what would work.
I am afraid I am very basic with my modelling motors, speed controllers, servos and Led's I am okay with. GPS and Arduino are out of my league.
I think in hindsight 1/72 may be a bit large for 4ft x 2ft tank so I have decided to look at smaller kits
The tug at 1.108 looks usable we do have a couple of these tugs left over from a diorama we built but a new kit would be the answer.
Again thanks for all your replies this all came about while having a coffee in the café with some of the members from our club.
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Skimmer Fan

Colin Bishop

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Re: Automating boat movment
« Reply #21 on: October 14, 2019, 12:11:39 PM »

Cheap enough to try out. You could consider mounting the vertical pole in a tube inside the boat so it has a bit of up and down movement and the magnet can retain contact with the wire if there is some wave (or ripple!) movement.

Colin
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Skimmer Fan

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Re: Automating boat movment
« Reply #22 on: October 14, 2019, 12:15:06 PM »

Thank you Colin nice suggestion things will keep evolving.
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Skimmer Fan

McGherkin

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Re: Automating boat movment
« Reply #23 on: October 15, 2019, 01:12:13 PM »

Miniatur Wunderland in Hamburg, Germany (look them up, you won’t regret it!) have been playing with autonomous ship control. They use several cameras on the ceiling and the vessel’s navigation lights to determine the boat’s heading and position and it then drives the boat remotely.


You could use differential GPS with a few cm’s accuracy but those systems are typically bulky and very expensive.


It sounds like the low tech solution suits your needs better though.
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grendel

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Re: Automating boat movment
« Reply #24 on: October 15, 2019, 02:42:05 PM »

I have a Arduino based tracked vehicle (boot fair purchase) that can using a set of ultrasonic detectors, steer itself around obstacles.
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