Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: loki on February 01, 2010, 02:03:48 AM
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To have something that could turn a specified number of times.
For instance in sail boat automation,
can turn a wheel that pulls a string connected to a sail several times,
in a certain direction.
I'm wondering how this can be accomplished.
I'm willing to work with smaller scale items (model sails) first.
Perhaps a stepper motor will be the best for this application?
Is there a tutorial on building one?
I'm also wondering if it would be better to use a small stepper motor,
and use gears to get high torque to turn sail cord rolls,
or to make/attain a high torque stepper motor.
Adsolutions appreciated.
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the only systems i've used on full scale sailing yachts have been hydraulic.
usually there is just a pair of hydraulic winches which you can put any rope round.
i have sailed on a boat that had a hydraulic system connected to every rope. you had to go on deck to initially raise the sails but after that everything (including reefing) could be done from inside.
http://www.google.ie/search?q=hydraulic+winch+sail (http://www.google.ie/search?q=hydraulic+winch+sail)
i believe there are electric winches available as well but i've never used them.
if i was building a model sailing boat though i would use servo motors.
they would be more than capable of handling the torque involved and far easier to control than stepper motors.
dunk.
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Hi,
For R/C-models there are several like this Sail Winch Servo (http://www.rc-fever.com/hitec-analog-sail-winch-servo-110g-11kg-168s-hs785hb-p-7493.html).
But I gather you wanna make one for a real size boat?
If that's the case, go with a DC motor to save trouble and cash.
First thing to do is to establish the speed and torque needed in a worst case condition (i.e. lots and lots of wind to fight) and then add at least 50% to counter ageing and bad luck.
So...
How fast do you wanna pull the sail how high?
How hard do you have to pull manually (if that's what you do now).
12V/24V/Something else?
If I'm not entirely mistaken, winches with a hand crank can be bought for heavy sails - perhaps it would be prudent to just modify such a beast for motor drive.
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I have played with some small scale (~20') unmanned sail boats before. ( I work for a Navy R&D lab) What the contractor realized was robotic sail boats with ropes is a bad deal. They moved the motor directly into the mast, which got rid of all the ropes. This requires a motor with more torque, (and i presume some sort of braking system to hold the sail against the wind) but gets rid of all sources of entanglement and less moving parts to jam. (pulleys, etc).
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the only systems i've used on full scale sailing yachts have been hydraulic.
usually there is just a pair of hydraulic winches which you can put any rope round.
i have sailed on a boat that had a hydraulic system connected to every rope. you had to go on deck to initially raise the sails but after that everything (including reefing) could be done from inside.
http://www.google.ie/search?q=hydraulic+winch+sail (http://www.google.ie/search?q=hydraulic+winch+sail)
i believe there are electric winches available as well but i've never used them.
Would you know of a tutorial on how to make a hydraulic winch?
Or even the blue prints for one.
if i was building a model sailing boat though i would use servo motors.
they would be more than capable of handling the torque involved and far easier to control than stepper motors.
dunk.
Hi,
For R/C-models there are several like this Sail Winch Servo (http://www.rc-fever.com/hitec-analog-sail-winch-servo-110g-11kg-168s-hs785hb-p-7493.html).
But I gather you wanna make one for a real size boat?
If that's the case, go with a DC motor to save trouble and cash.
First thing to do is to establish the speed and torque needed in a worst case condition (i.e. lots and lots of wind to fight) and then add at least 50% to counter ageing and bad luck.
Can I really control how many times a DC motor turns?
So...
How fast do you wanna pull the sail how high?
it's mainly for cruising long distances,
so can be relatively slow.
and winch is stationary.
How hard do you have to pull manually (if that's what you do now).
12V/24V/Something else?
I thought watts would be more relevant.
Though I'm fine with using the minimal amount with a safety margin.
Would it be measured in joules of work?
If I'm not entirely mistaken, winches with a hand crank can be bought for heavy sails - perhaps it would be prudent to just modify such a beast for motor drive.
[/quote]
that's what I was intending.
I have played with some small scale (~20') unmanned sail boats before. ( I work for a Navy R&D lab) What the contractor realized was robotic sail boats with ropes is a bad deal. They moved the motor directly into the mast, which got rid of all the ropes.
This requires a motor with more torque, (and i presume some sort of braking system to hold the sail against the wind) but gets rid of all sources of entanglement and less moving parts to jam. (pulleys, etc).
I prefer to have a stayed mast.
Easier to prep for submerging.
am planing on using a hanging crab sail.
uses 4 ropes/winches.
planing on having manual winches in the boat,
and connecting the automatic turners when cruising.
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Would you know of a tutorial on how to make a hydraulic winch?
Or even the blue prints for one.
i don't think you'll find one online.
hydraulic motors are used in a huge range of mechanical applications though so i'm sure you'll find information on just the actuator part.
If that's the case, go with a DC motor to save trouble and cash.
waterproofing an electric version would be a challenge but you could try looking into those winches they use on 4wd vehicles for pulling them out of the mud.
Can I really control how many times a DC motor turns?
this is going to be a challenge with either a hydraulic or DC system.
in my experience when sailing in storm conditions everything you can possibly imagine breaking will.
some things you can't imagine breaking also will.
some sort of encoder would be the best solution i think.
am planing on using a hanging crab sail.
interesting.
the first boat i ever rigged had a lateen rig which is very similar.
i'm not sure i would use it for cruising though. only having a single sail is a big single point of failure.
having said that, ancient civilizations used this sail plan for 1000s of years just fine.
do you have a hull yet?
dunk.
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Would you know of a tutorial on how to make a hydraulic winch?
Or even the blue prints for one.
i don't think you'll find one online.
hydraulic motors are used in a huge range of mechanical applications though so i'm sure you'll find information on just the actuator part.
if you could link to something I'd be grateful.
If that's the case, go with a DC motor to save trouble and cash.
waterproofing an electric version would be a challenge but you could try looking into those winches they use on 4wd vehicles for pulling them out of the mud.
Can I really control how many times a DC motor turns?
this is going to be a challenge with either a hydraulic or DC system.
in my experience when sailing in storm conditions everything you can possibly imagine breaking will.
some things you can't imagine breaking also will.
some sort of encoder would be the best solution i think.
encoder? the only kinds of encoders i'm familiar are for language translation,
like encoding mp3's from wav's.
am planing on using a hanging crab sail.
interesting.
the first boat i ever rigged had a lateen rig which is very similar.
i'm not sure i would use it for cruising though. only having a single sail is a big single point of failure.
having said that, ancient civilizations used this sail plan for 1000s of years just fine.
[/quote]
I was thinking of having a ketch sail in the back.
that would need three ropes.
one of the ropes on each sail,
I was intending to use to get the boom closer to the mast,
loosening the sail, much like reefing it,
so making it better for higher winds like storm conditions.
I'm assuming it will work,
I haven't tried.
Someone mentioned automatic reefing.
though I'd be happy for it begin working even in just calm weather,
just to create more free time for boat occupants.
do you have a hull yet?
I'm still on the modeling phase,
in the process of completing a wooden model,
here's a link to the boat design with pictures of drawing and models,
http://lokiworld.org/wordpress/?p=558 (http://lokiworld.org/wordpress/?p=558)
It's designed to be easy to build,
and good for all weather,
including winter,
since current locus is Canada.
In this lifetime I'm a hereditary computer programmer,
but have sailing and boating experience from some past lives.
admitedly the schooners of yesteryear don't much resemble nowaday boats,
but it's still hoist the sails and we'll get underway.
I like seasteading it's the new physical frontier.
I figure I'll have more time and freedom for working on various projects.
It seems like people on land get smuggled away by secret services if they make any significant discoveries.
In that sense it's safer to seastead.
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if you could link to something I'd be grateful.
i don't know where you'd go about buying one but this is the sort of thing:
http://en.wikipedia.org/wiki/Hydraulic_motor (http://en.wikipedia.org/wiki/Hydraulic_motor)
machinery i've used that contains them includes those 6 wheel drive Argocats http://www.argocat.com/argo.html (http://www.argocat.com/argo.html)
as well as those cherry-picker machines that are used on building sites http://www.cherrypicker.ie/ (http://www.cherrypicker.ie/).
all those devices have a central hydraulic pump and a hydraulic motor on each wheel.
maybe if you can find a servicing center for that machinery you'll find someone who knows about small sized hydraulic motors...
alternatively, i know there are a few mechanical engineers on this forum. maybe one of them will comment....
encoder? the only kinds of encoders i'm familiar are for language translation,
like encoding mp3's from wav's.
this should explain it:
http://www.societyofrobots.com/sensors_encoder.shtml (http://www.societyofrobots.com/sensors_encoder.shtml)
basically, you want some sort of sensor for measuring how many times your winch has turned.
anyway, good luck with the project.
sounds like you've a long way to go.
dunk.
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Hi,
If that's the case, go with a DC motor to save trouble and cash.
waterproofing an electric version would be a challenge but you could try looking into those winches they use on 4wd vehicles for pulling them out of the mud.
Is something escaping me? Would a hydraulics system not need an electric motor for making the pressure?
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If that's the case, go with a DC motor to save trouble and cash.
waterproofing an electric version would be a challenge but you could try looking into those winches they use on 4wd vehicles for pulling them out of the mud.
Is something escaping me? Would a hydraulics system not need an electric motor for making the pressure?
yes, you'd need some sort of compressor but it wouldn't live on deck.
but yes, i take your point. it's going to be a challenge waterproofing anything that lives on deck. it's a horribly abrasive environment.
that applies to a hydraulic motor as well.
i *presume* hydraulic motors are by their nature more salt water resistant than electric motors but corrosion will still be an issue.
maybe there are factory sealed electric motor/gear box modules available on the market?
that would be an option worth exploring.
both electric and hydraulic anchor winches are commonly available.
i've never installed one. i wonder what sort of motor they use?
a completely different argument would be that these motors (whatever type) are going to be relatively inexpensive compared to the overall value of the yacht.
as the safety of the yacht will depend on them i would argue strongly to look into the commercially available options as well.
i used to do a lot of heavy weather yacht deliveries.
systems that typically broke on boats i was moving are electrics, engines, rigging and sails. in that order.
by building your own winches you are mixing the first and third item on my list to control the fourth....
but these are all just my hunches and guesses.
i have used precisely 1 boat with any sort of automated system for sheeting and that was for a single trip around 15 years ago.
i think you need to find out about the commercially available options and use those to base your designs on.
keep us informed though.
i might be biased but it sounds like a fascinating subject to me.
dunk.