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Author Topic: feedback for Rewire of Southampton  (Read 2739 times)

Ghost in the shell

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feedback for Rewire of Southampton
« on: July 27, 2007, 07:00:19 PM »

if you have rewired a southampton RTR tug leave your feedback here
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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #1 on: September 18, 2007, 12:51:30 PM »


Ghost,

So, I did what you said here:

http://www.modelboatmayhem.co.uk/forum/index.php?topic=5248.0

....and it was pretty much Ronseal. (it does what it says on the tin....)

I used a GWS V Tail mixer II, plugged both ESCs into the the mixer, and then plugged the mixer's two outputs into channels 3 and 4 on my Futaba 6EX 6 channel system's receiver - left hand stick forwards and backwards as per normal, with left and right = throttle steering, with right hand stick rudder as per normal.

Time taken to complete = 20mins including waiting for the soldering iron to heat up! :)

Cheers Ghost, nice walk through.

-Rob
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Martin [Admin]

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Re: feedback for Rewire of Southampton
« Reply #2 on: September 18, 2007, 01:19:10 PM »

Hi Roberto,

With your mixer setup, will your Wyeforce, sorry Southampton pirouette on the spot?

Martin.
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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #3 on: September 18, 2007, 01:35:32 PM »


Cough... yes the 'Southampton'....

Until I either:

a. Get a bigger bath,

or

b. Go out sailing,

I don't know, but 'b' looks like being fulfilled in the next few hours :)

'Watch this space' as they say!

:)

-Rob
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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #4 on: September 18, 2007, 09:13:36 PM »


Right then!

I've just come back from sailing the River Dee at the upper part of Chester, in the wind and waves, and can confirm that the setup that I've used allows the Southampton to spin on axis an down through the centre line of the mast, when you throw both sticks either hard left or hard right. The turning circle has reduced from 12 odd feet down to turning in place - twin ESCs + VTail mixer for the win! :D

-Rob
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Martin [Admin]

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Re: feedback for Rewire of Southampton
« Reply #5 on: September 18, 2007, 11:12:07 PM »

So how have you got the sticks set up?
For V tail mixing, do you have both motors on the R/h stick ( elevator and ailerons) ?
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Ghost in the shell

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Re: feedback for Rewire of Southampton
« Reply #6 on: September 18, 2007, 11:16:17 PM »

martin if you have the 6EXA family, you need ELEVON mixing to do the job of mixing in throttles, as opposed to buying an off the shelf V-tail mixer. I have used that set up on my Yamato, however I may adapt it to the southampton at some stage when i change her esc's for overlanders as at full stick forwards then deflect to left/right one motor cuts out completely, which i believe to be an ESC problem, not a mixing problem as yamato does the same.

by the way it feels alien using the right stick for motor control
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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #7 on: September 19, 2007, 03:33:05 AM »

So how have you got the sticks set up?
For V tail mixing, do you have both motors on the R/h stick ( elevator and ailerons) ?


All motor control is on the lefthand stick, with just the rudder on the right hand stick.

That way you can manoeuvre in tight spaces using the left to right movements of the throttle stick plus the rudder, or you can use the throttle and rudder normally for more general point to point travelling on the water. I quite like this setup :) I'm not over enamoured with rudder/throttle mixers due to the fact that the mixer is 'always on' - Using the V-tail mixer with the throttle steer on the left stick gives you the choice of not using the mixer at all.

I did notice some throttle cut outs initially when trying to use the throttle steer at full forward throttle, but a little playing with the end points of channel 4 sorted it out to my satisfaction.

I don't like the way that my usual throttle/rudder mixer interferes with the high speed running of my Trent lifeboat, so I may well convert that to a V-tail mixer too.

I've just ordered in some cheapo V-tail mixers from HK via ebay at 4.75 a pop, I'll see what they go like - mind you the GWS unit was only 13ish quid here in the UK.

As you may have gathered, I like the V-tail mixer solution alot (!) ;D

-Rob

-Rob
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OMK

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Re: feedback for Rewire of Southampton
« Reply #8 on: September 19, 2007, 04:37:51 AM »

>>"All motor control is on the lefthand stick, with just the rudder on the right hand stick."

Rob,
This will probably sound terse, if not cheesy, but would your statement still hold true if the user was left-handed?
Only reason for asking is because I used to date a south-paw. She totally mashed my first-ever-build just because "you should have stuck the rudder in my OTHER thumb!", sort of scene.
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Martin [Admin]

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Re: feedback for Rewire of Southampton
« Reply #9 on: September 19, 2007, 09:06:34 AM »

Ah sorry, a false assumption on my part. You are using an independent V-tail mixer ( a 'magic box'  in the model ) as opposed to the inbuilt mixer in the transmitter hence the ability to mix any channels you want to. ( Most in built mixers - V & Elevon are limited to certain channels! ).
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tolnedra

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Re: feedback for Rewire of Southampton
« Reply #10 on: September 19, 2007, 10:39:48 AM »

Hi PMK

I'm left-handed, and use Action mixers in my coast guard boat and my All Khubar. When setting up I choose to use left stick for rudder, and right stick for motor control, works fine for me! It does confuse other club members at times, when they have a go with my boats!

Danny
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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #11 on: September 19, 2007, 01:23:22 PM »

>>"All motor control is on the lefthand stick, with just the rudder on the right hand stick."

Rob,
This will probably sound terse, if not cheesy, but would your statement still hold true if the user was left-handed?
Only reason for asking is because I used to date a south-paw. She totally mashed my first-ever-build just because "you should have stuck the rudder in my OTHER thumb!", sort of scene.

Good point!

I develop/implement/utilise control systems that are user or tx/rx system agnostic(!).

Eh? I do alot of fitting out work of control systems for fellow club members/friends/associates. These people may indeed be lefthanded, and probably already have their own preferred tx/rx system too. (Current project design/implement a control system for a new, as yet unbuilt, 1/16th Severn Lifeboat).

Going back to your enquiry, most righthanders (not all!) use a mode 2 setup - throttle on the left, alot of lefthanders tend to spec, or own a system with  throttle on the right (mode 1) - the separate V-tail mixer solution works well because you can use it on either side of the transmitter (left or right stick).

So, not cheesy at all, and an issue I'm all too familiar with! :)

-Rob
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timflan

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Re: feedback for Rewire of Southampton
« Reply #12 on: December 26, 2007, 07:55:38 AM »

OH! I think I finally get it! I was thinking the mixer took the rudder input and used it to modify the power applied to the motors. I just figured out that I was wrong, from this thread. Thanks, Rob, in particular.

So let me get this straight:
The right joystick controls the rudder in the conventional way.
The left joystick works in the conventional manner if you move it forward or backward.
If you move the left joystick to the right, the starboard motor reverses and the port motor advances, pivoting the boat to the right.
If you move the left joystick to the left, the port motor reverses and the starboard motor advences, pivoting the boat to the left.

Questions:
What happens if you move the left joystick forward AND right? Backward AND right?
If you move the left joystick to the right and give reverse rudder (right joystick to the left), will the boat crab to the right?

Thanks!
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FullLeatherJacket

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Re: feedback for Rewire of Southampton
« Reply #13 on: December 26, 2007, 09:28:32 AM »

OH! I think I finally get it! I was thinking the mixer took the rudder input and used it to modify the power applied to the motors.

Yep! That's exactly what it does. The "LH stick sideways" movement doesn't figure in the equation - most folk will use that one for a bow-thruster. This should help explain things:



As Danny T says, you can reverse the sticks if you're left-handed, but obviously not on a two-channel Tx as shown.

If you want to spin the model on its own axis then, with either of the current ACTion mixers, you apply a smidgen of throttle and slam the rudder stick hard over. This spins up the inboard motor into full reverse while the outboard one goes at full ahead.

Note that other on-board mixers may work in a slightly different way when it comes to how much reverse motor is applied to the inboard motor, but they all have the same stick arangement (as far as I'm aware). Suit yourselves, eh?

Ghostie - your problem is almost certainly that the ESCs are programmed to failsafe (shut down) if they see any signal outside a certain pulse-width range (say 0.9ms - 2.2ms), whereas the software which controls the mixing in your tranny will put out a signal of maybe 2.4ms at "full everything". The reason is that servos aren't anything like as fussy as speed controllers and will simply rotate just that little bit further. Can you adjust the servo end-point on your computerised gizmo to restrict the maximum throw when you plug test servos into the mixed channels? That might help.

Just another bit of evidence that most radio manufacturers don't properly cater for boat-modellers?

FLJ


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Robert Davies

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Re: feedback for Rewire of Southampton
« Reply #14 on: December 26, 2007, 03:20:25 PM »

OH! I think I finally get it! I was thinking the mixer took the rudder input and used it to modify the power applied to the motors. I just figured out that I was wrong, from this thread. Thanks, Rob, in particular.

You're welcome! I think.....

Quote
So let me get this straight:
The right joystick controls the rudder in the conventional way.
The left joystick works in the conventional manner if you move it forward or backward.
If you move the left joystick to the right, the starboard motor reverses and the port motor advances, pivoting the boat to the right.
If you move the left joystick to the left, the port motor reverses and the starboard motor advences, pivoting the boat to the left.

After some imaginary stick twiddling on my part, yup that's right.

Quote
Questions:
What happens if you move the left joystick forward AND right? Backward AND right?

See FLJ's reply to Ghost above - For partial stick movements pretty much as you'd expect - However the effect is better achieved with just the conventional rudder system on the right stick.

Quote
If you move the left joystick to the right and give reverse rudder (right joystick to the left), will the boat crab to the right?

Questions... Always with the questions ;)

In theory - yes - In practice - not so much....

My head hurts too much to even begin to explain why at this time on Boxing Day! :)

Quote
Thanks!

You're welcome.... Such a polite young man.....


-Rob
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timflan

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Re: feedback for Rewire of Southampton
« Reply #15 on: December 26, 2007, 06:51:25 PM »

FLJ, thanks for the helpful diagram. Hmmm. It seems like FLJ is talking about a different arrangement from the one Rob describes here:

All motor control is on the lefthand stick, with just the rudder on the right hand stick.

That way you can manoeuvre in tight spaces using the left to right movements of the throttle stick plus the rudder, or you can use the throttle and rudder normally for more general point to point travelling on the water. I quite like this setup :) I'm not over enamoured with rudder/throttle mixers due to the fact that the mixer is 'always on' - Using the V-tail mixer with the throttle steer on the left stick gives you the choice of not using the mixer at all.

I would like rudder control and motor control to be independent from one-another. Even if the boat won't crab very well, I'd like to be able to play with it and figure it out as best I can.

OK, so here's what I IMAGINE happens with Rob's arrangement. For the moment, we'll ignore the rudder position, since it's independent.

[throttle stick position]: [result]
centered: all stop
forward: all forward
back: all reverse
right: port forward, starboard reverse
left: starboard forward, port reverse
  (ok, here's where it gets tricky...)
forward & right: port engine forward, starboard engine stop
forward & left: starboard engine forward, port engine stop
  (and now the really tricky part...)
backward & right: starboard engine reverse, port engine stop. Boat reverses and nose turns right.
  (OR...)
backward & right: port engine reverse, starboard engine stop

Let's line these up as if we had the stick all the way to the right and were sweeping it from forward to back...just to see if one makes more sense than the other. Either could be perfectly intuitive, once you got the hang of it.

The "Right Means Right!" model:
forward & right: port engine forward, starboard engine stop
right: port forward, starboard reverse
backward & right: starboard engine reverse, port engine stop. Boat reverses and nose turns right.

  (OR...)

The "Just Like A Rudder" model:
forward & right: port engine forward, starboard engine stop
right: port forward, starboard reverse
backward & right: port engine reverse, starboard engine stop

"Just Like A Rudder" model seems attractive, but the port engine has to go from full forward to full reverse within a very short throw space. I doubt a simple mixer does this. After giving it some thought, I wonder if "Right Means Right" isn't the behavior you actually get, Rob?

OK, better get to work on something lucrative to pay for the computer radio I'll need to do what I want...
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timflan

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Re: feedback for Rewire of Southampton
« Reply #16 on: December 31, 2007, 06:48:00 PM »

OK, I'm pretty sure I've figured it out. It's the "Right Means Right" model, and it's used routinely on RC tanks for independent control of the motors using a single joystick. Independent motor control is the only way they can maneuver, of course. Concepts such as "rudder" and "steer" don't enter into it.

In a simple car or boat, turning the steering mechanism right causes the vehicle to point its nose to the right in forward, but to the left in reverse. On a tank, turning right means you want to turn right, regardless of whether you're moving forward, backward, or stationary.

I THINK I've got this right. Somebody please set me straight if I'm still confused...it's pretty likely, actually.

I've also learned that there are dedicated tank mixers designed to mix input for ESCs, rather than servos. Shouldn't really matter, but might as well get the one that does the thing I need done. Especially if it happens to be waterproof, as is this one:

http://www.mtroniks.net/mtroniks_products.asp?CategoryID=11&SubCategoryID=38
(about halfway down the page)
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