Ok, let’s talk about something usefull (sorry, I could’t resist)
I got some of this servos https://www.olimex.com/Products/RobotParts/ServoMotors/MS-R-1.3-9/ which basically are endless winch (they run clockwise and anticlockwise, with the speed depending on the position of the trasmitter stick) with a torque like a mini-servo often used on the footy.
Since the weigth is less than a tipical Hitec HS85MG, I am thinking to use one of it on my next footy (the futinett by ClaudioD).
Aside the obvious problem with the endless motion, which imply that it need a greater degree of attention when sailing, there are some other problems I cannot see ?
The idea is to have a swing rig controlled witha system similar to the one used on the IOM (with a rubber band)
The torque should not be a problem, since with a 1 cm (diameter) drum, I still have almost all the nominal torque. Since it is a winch, I not have problem with the travel, which anyway is more than I need.
Only a thought … The biggest fear I would have is being able to stop the winch when needed - and keep it from “over-rotating” which could cause damage to rig - and possibly the hull. If using a programmable winch and transmitter that can set end-points, that issue might not be a problem.
The winch should (and it does) stop when the stick in in the center position.
The servo is not programmable, since it is build to achive continuos rotation, it is used to built robot (I suppose for the wheels)
The problem of over-rotating will be always present but probably a work around can be a failsafe method in which something breaks in a controlled way, so ok, the winch don’t stop, the failsafe breaks and the boat does not suffer too many damages, if any.
Can be this a solution ?
It is a solution, but if something is designed to break, and it happens on the water or during a race, you then have the possibility of a “Non-Finish” !! Your rig “could” be this item, but if the sail/mast fails, then you have an issue getting to shore.
If the boat is (say) 10 meters away, can you really see or count revolutions before something breaks? I am not sure how many times I have moved the stick the wrong way then I had intended when sailing. Oooops ! :shake:
You are right. My plan is to have the breaking point in a position where it cannot damage the sail/mast/hull. Somewhere on the stay, for example.
If the boat is (say) 10 meters away, can you really see or count revolutions before something breaks? I am not sure how many times I have moved the stick the wrong way then I had intended when sailing. Oooops ! :shake:
Ok, you have a point
Let’s see… perhaps this can be solved using a closed loop, so a swing rig (or any other rig, I suppose) is always in the correct position, which give a feedback how many revolutions were done.
This, however, has the disavantage that it is harder to design a programmed breaking point.
In the case of the old worm gear driven (linear, Archimedes screw) winch systems, a limit switch stopped the servo at each extreme.
With a closed loop system a loop in the line could similarly pull on a switch at each extreme to reverse the direction.
I am not sure of the electrics of this but should be possible with a servo polarity switch?
The servo is low torque so would likely be pushed in moderate winds even with a balanced rig. I use a Tower Pro SG90 similar servo with a McRig and a Stollery Power Lever which is ok if you remember to unload the sail before winching in over about 5 knots.
I have seen a project like this on a French Forum some years ago. It was used to operate a genoa and work with motors, not servos (it was some type of IACC derivate class, perhaps the ACC20, I am not sure).
I like your idea, but if I understand it well, you should have something more complicated than a switch, since when you reach one extreme (let’s assume rotating clockwise), you should prevent only additional clockwise rotation, but not the anti-clockwise rotation (and vice versa)
Also if this is doable with and Arduino or something similar, you add another component to the boat, which need power and can break.
I’d prefer a pure mechanical failsafe, since it seems simpler to me. But you had a great idea.
The servo is low torque so would likely be pushed in moderate winds even with a balanced rig. I use a Tower Pro SG90 similar servo with a McRig and a Stollery Power Lever which is ok if you remember to unload the sail before winching in over about 5 knots.
Probably you are right, but with a very little drum I am planning, I should ease the problem.
The only way to be sure is to try, I suppose
Hey y’all;
Been gone for several years. Even though last reply was pushing a year ago, this is a topic of interest, and the winch thing is a bit intimidating, so have subscribed to thread. After shoving cat out of the way so I can type.
Forrest
(sorry, I could’t resist)
