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Pypilot working on my Nicholson 44
#11
[attachment=752 Wrote:seandepagnier pid='12155' dateline='1580407641']How did you drive the shunt coil of the motor?   To make it reverse, current must be the same direction through one coil but not the other...    Did you use a bridge rectifier, or connect it to the clutch output (always energized) or?

The shuntcoil is driven through the clutch, always on when clutch is engaged. (Consumption is about 0,1 Amp/24V) Clutch is engaged by pin 11 on arduino with your motor.ino trough an ssr-relay. I just use three pins of the arduino, Pin11 for Clutch, Pin9-RC for the Pololu Motor driver and Pin-Gnd for comoun ground. I reverse the polarytiy amature for change of direction.
I enclose my scratch, sorry it is not verry profesional ....
greetings and save sailing
Andreas


Attached Files
.pdf   Scratch.pdf (Size: 538.33 KB / Downloads: 122)
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#12
(2020-01-30, 07:07 PM)seandepagnier Wrote: How did you drive the shunt coil of the motor?   To make it reverse, current must be the same direction through one coil but not the other...    Did you use a bridge rectifier, or is the shunt powered through the clutch?

I was asking myself the same.
There is a detailed, well written explanation of the workings of the Neco and adapting it to a new controller by Daniele Fua:

http://www.nicholson38.org/wp-content/up..._35DR8.pdf

If I understand. The series and shunt coils are always in the same direction (the shunt coil paralleled to the clutch).

The current to the armature is reversed to change the rotation or shorted to brake the unit which presumably occurs between the times when the rudder angle is changing?

"The original circuit (see Figure 1) is essentially made by two changeover relays that take care of powering and inverting the current to the Armature while keeping the current direction in the Series Coil unaffected and short-circuiting the Armature when not powered. The Shunt Coil is paralleled to the Clutch Solenoid and its polarity is kept fixed. The Shunt Coil is powered all the time the autopilot is active, even when the motor is not turning; its function is to act as electromagnetic brake when the two changeover relays short-circuit the Armature of the motor."

(2020-01-30, 01:55 PM)xfactor99 Wrote: Hi Nick,

nice to hear from you and yes we met in November, I remeber you were on the way north ....

It's a great feeling when the virtual and real worlds intersect! I was a bit thrown by the photos of snowy mountains in the background in your dropbox but recognised your dog (!) in the video...

I'd really like to construct a pilot similar to yours. I've looked in to mating up the drive unit with a new propriety control head but I'd like to go the whole way of building a system myself. I accept that there will be a lot of learning but for me that is part of the attraction.
We did the 2000 miles from Ireland without autopilot, just two of us. The long keel is a pain in marinas but great in open water!

I'm interested in how you have managed the limit switches. Given the torque of the motor unit this has been a major concern of mine since I started thinking about a conversion.
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#13
Andreas
On my existing pilot there seems to be no speed control of the motor, I have often noticed that small rudder corrections are made at full motor speed which seems to put a lot of inertial stress on the steering system as it is jerked continually left and right. Does your system allow for any speed control to ramp up and down the accelerations?

not sure what went wrong with my previous post, I intended your text to be in a quote box.
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#14
You can adjust the acceleration and deceleration limits as well as minimum and maximum motor speeds though the servo parameters for speed and slew speed.
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#15
[attachment=753 Wrote:nick.k pid='12162' dateline='1580420703']Andreas
On my existing pilot there seems to be no speed control of the motor, I have often noticed that small rudder corrections are made at full motor speed which seems to put a lot of inertial stress on the steering system as it is jerked continually left and right. Does your system allow for any speed control to ramp up and down the accelerations?

not sure what went wrong with my previous post, I intended your text to be in a quote box.

Hi Nick,

Limit Switch:
The great torque of the NECO-DRIVE (=ND) is of concern when it will go to or over the rudder limits. There are serveral aproches to prevent: First at all i mounted an interupt switch into the clutch cable installed to the cocpit near the helm to disengage the ND when erver I need !!! 
Then for testing porpouses of the ND y had the chain that drives the rudder taken off.
Then I installed interrupts Limit switsche, now I have maecanical at the rudder to stopp driving when at the limit. I use this ones as I found them more reliable the the fromer reed I had (mayby because my poor istall of the reeeds) 
https://www.cetronic.es/sqlcommerce/dise...cPath=1160
I add a photo of the install.
The LS can be wired to the pololu or to the arduino .... I have them directly to the arduino.
An other aproach is to use your switches at the ND ..... or you use both both LS at the rudder and the ones at your ND
Other posibilities are: disengage on mesurement of stall current, Seans Driver and the arduino and the pololu will allow, an I thin also the Pololu G2, or using an rudder angle sensor to the arduino, and difine the limits in the Pypilot.
I think as closer you go to the ND-Cirquit as saver it becomes.
Mine go to the pins of the Pololu ....

Rebuild Neco Drive
I see you have the instructions of Daniel Fua, that is basicly what you need. I use the pololu wich makes it still easyer (See my wireing-scratch on my post before)
For me the advantage was that I can test the ND, the LS, and also speed settings on the Laptopp with the popolu software without the Autopilot electronics.
So on one side I have only the ND, settings and testing until it works, and on the other side I have the Pypilot electronic with the arduino, (I use LED´s green,red and yellow for the clutch to test it).

To join the ND and Pypilot later you need yust a 3 cables (Pin 9,11,Gnd) from the arduino to the ND.
Disadvantage is you need the Pololu ablut 60€, and as my setup I do not use current/voltage information consumption of power ect. . 
I´m sure you can get this through the Pololu or adding sensors to the arduino. But my aproach was to have a fast solution witch works reliable and go sailing ....
You will be cheaper if you make your own driver of a H-Bridge with Mosfet´s and Daniel Fua´s instructions to take care of the Compund Motor caracteristic.


Speed setting:
As Sean stated you can set speed and inicial speed and stopping speed at the Pypilot servo settings. You also can set them at the pololu ....., I tried it with the pololu/Laptopp and speed setting of 50% and the neco reacts fine but I did not go depp into this (yet) as I´m not unhappy with the movements as you could apreciate in the videos at the posts before ...

Hope this helps, have good fun
Andreas

I sent you also PM if you need direct contact ....


Attached Files Image(s)
   
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#16
Thanks Sean and Andreas for such detailed replies.

I'll start designing a pilot for my 48 and document it on a new thread. I have a pile of learning to do so any help on the way would be much appreciated!

Nick.
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#17
Photo 
I installed today my new ap-control at the hem,

   

Save sailing
Andreas
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#18
(2020-02-07, 05:25 PM)xfactor99 Wrote: I installed today my new ap-control at the hem,



Save sailing
Andreas

Hey that looks great!!
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#19
(2020-02-07, 05:25 PM)xfactor99 Wrote: I installed today my new ap-control at the hem,



Save sailing
Andreas

Looks like a very nice control-panel installation; Particulairly, the acknowledgement/labelling of "WWW.PYPILOT.ORG" in the lower right corner!

Congrats!!!
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#20
Andreas ==>

Thanks for all this information.  I too am replacing on old Robertson, and have the same NECO drive motor (only mine is 12 VDC) and the same, I assume, motor controller in the blue box mounted to the motor.  All this on our 1974 42' Solaris catamaran.

My big question is:  Do you find  that the drive motor eats up the batteries -- sucking them down on long continuous use of the autopilot?

I am considering replacing the motor with a more efficient modern one, like:

https://makermotor.com/pn01007brkt-50-rp...h-bracket/  (with appropriate sprocket for the #40 chain).

This new motor is rated at a "Rated Load: 60 Watts"

Any ideas or suggestions? 

(Obviously, the easiest thing to do is what you have done and just keep the old NECO motor....but...power usage?)

Thanks,

Kip
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