Winch
 

Has anyone thought about how to winch themselves up to the bar. I was thinking about taking apart a boat trailoring winch and using cable. Any ideas?

Re: Winch
 

Yep. Looks like this is a popular idea. I know we have been considering it. Here is a thread with a discussion about how winches work and some opinions of them.

http://www.chiefdelphi.com/forums/sh...ighlight=winch

Re: Winch
 

ive desinged a winch
its a Plug&Play winch that reals 15" Per second with a max lift load of 486 Lbs

Re: Winch
 

I don't want to thrash, insult, or even knock the idea of a winch (trust me we would be using one...), but given the 10ft/s rule, how do you plan to address the case of missing the bar with your winch (I'm assuming you're throwing it or somethng of that nature)?

Re: Winch
 

the winch looks nice tytus... seems like you are suggesting to use chiphua motor which is also known as atwood. there are lot of teams out there who would use the chiphua for drive train... a lot of team out there had drill and chiphua using for drive train last year, and they might do it again. what would you suggest using some other motor such as window or globe... its probably gonna take a while for the winch to move... but there is going to be a lot of torque...

Re: Winch
 

were talking about winches not about how your getting the cable up on the bar Save that for elsewhere

Re: Winch
 

Actually I think he's using the van door motor. Notice the gearbox at the end. This is better than using the CIM because the van door motor uses a worm gear, which means it cannot be backdriven(at least theoretically) so you don't have to worry too much about it falling after power is cut at the end of the match.

Re: Winch
 

Nice looking winch. Thanks for posting it, we might use it.

Have you considered cutting a helical groove in the drum to keep the cables from crossing and tangling? This is common for many automotive applications (window lift mechanisms, power sunroofs, etc.)

How will you anchor the ends of the cable into the drum?

Looks like the power van door motor in your design which is a non-backdriveable worm gear, meaning it requires no brake to keep you hangin. An appropriate application. :)

Re: Winch
 

its just a hole in the drum
If you have more questions about my winch Im me or e-mail me. Keep the back and fourth klutter off the forums.

Re: Winch
 

i apologize.. i was about to edit the whole post when you replied back... i didnt really pay a lot of attention to the whole post from tytus... and i looked at the winch mechanism from the bottom view... and i am pretty sure that anybody will make that mistake thinking its a atwood... if they have just seen it from the bottom view.... once again... i apologize...

Re: Winch
 

As an offshoot of the winch idea and as a way to save weight I would suggest researching lightweight stronger than anything rope. Particularly the type used on sailboats that is designed to hold incredible loads. Check it out:
http://www.layline.com/llf/llpages/h...riga/page2.htm

Just an example:
1/8" diameter
.6 lbs/100 feet
2200 lbs break load

Re: Winch
 

I was thinking the same thing. Infact, I have been researching boat trailor winches that are designed for rope. I figure I would strip them down.

Re: Winch
 

Use some other mechanism, such as a arm to put the hook up

Re: Winch
 

a great big old helium balloon! :)

Re: Winch
 

You would think so, but unfortunately I believe that's not the case with this particular worm drive gear; I seem to remember using it for a lift one time, only to find out it would backdrive when the power was cut - it had an oddball pitch angle so that it could be backdriven (a safety feature since it's used for closing van doors). I know they've changed the particular van door motor we get in the kit since a few years back - can anybody confirm if this motor can be backdriven?

Re: Winch
 

I can tell you that the van door motor will back drive. Plus you need to gear this motor better than you have it.

Here is a picture of us hanging
http://www.valleytech.k12.ma.us/robo...s/roboti87.jpg

That motor was being gear for a 24t to 48t. So if you think that buy just putting a drum on it would work let me save you some time.


The tyco motors into a gear box would be the best bet for this. 15,000 rpm reduced 200:1 would give you a good starting motor and if you put two of them together you would have a fast strong winch. you could say you could climb up at a rate of 6 pi = around 18" per second. which is 1 1/2 foot per second within 6 seconds you will be at 9 feet.

Make sure your winch can pull you and one other robot. by using the pass competitions someone might be holding you down

Re: Winch
 

The van door motors Can be backdriven it is just verv difficult

Re: Winch
 

how difficult? will it support the 130 lbs when the power is cut? That's really all I need to know..... :)

Re: Winch
 

The van door motor can be backdriven rather easily. I was able to do it with my bare hands, I doubt it will be able to hold up a 130lb robot. Another thing to look into is an electronic brake. I'm not completely familiar with the electronics, but I'm pretty sure the speed controllers have a jumper on them that will enable a "brake" of sorts. It electronically prevents the motor from being back-driven. I can't say if it will be able to hold 130lbs, but the two combined (van door motor + electronic brake) might be able to do the job.

[edit] The electronic brake remains enabled as long as the robot has power, so it will work after the robot is disabled at the end of the match.

Re: Winch
 

a pneumatic arm w/ winch attached to that could be an idea....

Re: Winch
 

the Van door motor and the speed control brake will not hold 130lbs This has been tested many times.

There is a easy fixs to all that and it is not hard to do.

Re: Winch
 

We've established that. If anyone actually wants to discuss how to build a winch, continue. If you're just going to post about how "the Van Door motors won't hold a robot" like the last 8 or so posters have, please don't, or I'll lock this thread.

Re: Winch
 

C'mon Jeff - discussing how to design / build a winch includes discussing how NOT to do it, especially if it's backed up by experience. If you want to know how a winch works, got to howstuffworks.com; if you're looking for more details on designing and building one within the constraints of the FIRST competition (including which motors to use) you look in these threads. I made the point that the van door might not be the best choice but I didn't have any recent experience or solid memory, so some people chimed in who did. A forum is just that - a forum for people to share ideas and experience. I hardly think the last few replies were beating a dead horse.

Re: Winch
 

If you want a way to use a winch try this


Take your drivetrain and put 2 motors per side to run it. When you are done moving use the same power to lift your robot.


A nice fast strong lifter


Have fun

Re: Winch
 

Gary, I very much agree that how NOT to build something is a good element of discussion. I did, however, feel it was starting to get off track, because people were starting with the "chiming in" replies that we're trying to prevent. It was intended to just be a friendly reminder to keep the discussion moving, so I don't have to lock a good thread because 10 more people decide they need to mention that a van door motor alone can't hold a robot. Anyways.... it's moving along again, so carry on.

Re: Winch
 

This doesn't quite make sense to me... are you saying power the winch via the same motors that are driving the main wheels?

Tytus made a good point that this is not the place to discuss methodology of attaching a winch to a surface. However, note: The bar is 9' from the platform and probably 5' from the average robot's winch "launch" point.
Vmax = 10 f/s
or
Vmax = 5 f / .5 s

I don't think it will be too much of a problem to "launch" a latch by a vertical means in over .5 seconds. Yes, I understand that a vertical launch is different from an arc'd launch, but you get the idea. 10 f/s is pretty darn fast.

Re: Winch
 

I would not launch anything, I would use a arm to deploy the cable. then bring the arm back in.

But back to the motors. You can tie in the drive motors to run the winch. this way you save on motors and get to have a very powerful winch. This can be done in many ways. I was just showing poeple ideas on what motors they could use to pull there robot up and anybody elses robot that wants a free ride up.


Less motors move power you can't go wrong.

Re: Winch
 

The van door can lift a robot .... we've actually built a "winch" that can pull up a 130 lb robot...and trust me it CAN be backdriven!

Re: Winch
 

Sounds like time for a little Physics lesson.

Power = work/time = torque*rotational speed = volts*amps

work = force*distance

We know the force we want, 130lbs minimum. If you're worried about another robot climbing on top or otherwise holding you down then double it.

How far do you want to go? if lifting from the floor you need to go at least a foot. To be safe I'd say two feet. So the work that needs to be done is 260 ft/lbs or 351 joules. Your robot is so feature packed that the only motor available is the lowly Globe. According to Dr Joe, the Globe puts out a maximum of 50 watts with the gear box.

To find out the minimum time it will take, we rearange the power equation above:

time = work/power or 351 J/50 W, 1 W = 1 J/s

so the time to lift 2' at maximum power is approximately 7 seconds. That is for 2 feet, one foot will take half that and more than do the job in most cases and you decide that is acceptable. The next step is to decide how big you winch drum needs to be.

Dr Joe also lists the stall torque for the globe at 19 Newton Meters. A weight of 130 lbs corresponds to 578 N. Now because of the way electric motors work, you probably don't want to run at anywhere near stall. I like to design things to run at 1/4 stall torque for a number of reasons I won't go into. To make things easy let's assume 4.75 Nm as the usable torque from the Globe.

The maximum drum radius (in meters) is then simply the usable torque divided by the force we want in Newtons. In this case 4.75 Nm/ 578 N = 0.0082m or 8.2 mm. A little further conversion gives a drum diameter of 0.647 inches. To get it to a standard size let's use 5/8" or 0.625". Since the drum is a little smaller we get a little more force which gives some margin. 0.625" = 0.0158 m and the force available is 600 N

Now to back check. At 1/4 stall torque the poor little Globe is going to be running at about 75rpm or 1.25 rev/sec. In 7 seconds it will go 8.75 revolutions. Each revolution pulls in pi*0.625" of drum so the amount of cable pulled in is

L = 8.75*pi*0.625" = 17.2"=0.44m

Checking the current draw:

600 N * 0.44 m/ 7s = 38 W

Amps = power/volts = 38 W/ 12 v = 3.2 A

Not quite the 2' we wanted, but we did reduce the shaft diameter somewhat which will reduce the speed at which the cable comes in. Since we are operating far below stall torque, there is probably plenty of excess to ensure this actually works. Also, the motor will be operating well below its maximum output. The current required is pretty low as well which will keep your electrical guys happy.

You could repeat the calculations with whatever motor your heart desires and the only things that will change are the time to lift and the drum size. It doesn't matter how much torque you have, just how long you're willing to take to get there. I picked the Globe to be a little on the rediculous side, but looking at the numbers, I might have to go redesign our winch. It'll probably save us a couple of pounds. Of course there's the cost of a few extra seconds, the strategy guys will have to figure out if we can afford that....

BTW whether a worm drive can be backdriven or not depends on the pitch angle of the worm. If it is >5deg then it will backdrive. Unfortunately this is the case with the van door motor, as I learned through hard experience.

Re: Winch
 

This is a really cheap design, but I made this in about 5 minutes in 3D studio max, just a real basic design, when I have time, i might make it more detailed.

Re: Winch
 

I heard people talking about how the motors can be backdriven. This is just a quick easy way to keep the spool from backdriving. the pins on top of the spool have one flat side and the stop would basically act as a ratchet so you can spin one way but not the other. The brake would have to be hinged at the red part in the back.

Re: Winch
 

Just as another example, in case you want something that winds better than 1/8" stuff, Small parts has some pretty strong Spectra Cord. 0.060" Dia, 861 lbs tensile strength. Pretty nice stuff, I think.

Re: Winch
 

1 word for cable material: 3/16" galvanized aircraft cable :) 2,500lbs test.

Re: Winch
 

Question: can chippawas be back driven? I'm an ignorant fool about this kinda stuff but I'm wondering 'cause I think I have an idea.

Re: Winch
 

In a word, yes. The Chip's can be backdriven, and it's not terribly hard to do so, especially when the power is off.

Re: Winch
 

Clarification Post: Please do not follow-up on this
Sorry I didn't clarify, my point about the Vmax was intended towards Jeremy_Mc's coment earlier in the thread.

Re: Winch
 

i just tested whe vandoor motor with a 1.5" spool on it. with no power i just leand back with the cable in hand and iot was backdriving

Re: Winch
 

When I started thinking about how I was going to pick up the robot this year, I also thaught winch, and at first I thaught van door motor, but yes, that darn backdriving thing killed that, So, I looked at some of the other motors in the kit, and I decided on using the globe motors, now each globe produces 150 in-lbs of torque, not too shabby, but cant have a side load, not a real big issue, as long as you have good bearings, and a tight assembly with little slop. it runs at about 100 rpm's no load, and that gets cut by a little more than half when there is this much load on it. now, you could get away with just one globe motor, and say a 2 inch dia. spool, would give you 150 lbs of lifting force, but it would be slow, you could increase the spool size, but then you loose force, again it would be slow, and one thing is, you don't want to sacrifice twenty seconds to just lifting the bot. so, like everything I've designed this year, im using two motors, and a drum, which will provide over 300 lbs of lifting force, and I can tell you it will take less than 5 seconds to live the robot two feet off the ground.

example:
torque(in-lbs)=force(lbs)*radius(in)
300in-lbs = 300lbs * 1in.

power(hp) = force(lbs) * radius(in) * rpm / 63025

If we know the hp rating of the globes, which we do, and it is just over .2hp, (.21hp), you can find out the rpms of the motor under a specific load.

yes, it really is that easy. but if you do use the globes, make sure whatever your turning is supported right, and with bearings, so that the motor dosnt see any side load, because no good can from that.

Re: Winch
 

Globe motors are good for lifting the robot but we use it not on the winch but as a lifter to get over the 6" side. We use the globe as it came and gear that down to 12:1 we only needed to turn the last sprocket 1/4 turn. so it takes 1.8 second to lift our robot 8 inches off the ground

http://www.valleytech.k12.ma.us/robo..._24wheels2.JPG


The winch we are using the Tyco motors and gear them down to 200:1. we are making our own gearbox and putting both Tyco motors into them.

We go up at a rate of 18" per second. pretty fast with power. This way if we have to go from the carpet we should be there quickly.

Re: Winch
 

it was kinda funny but dangerous at the same time last thurs, we were testing out winch w/ one of the guys standing on a platform he mounted to winch to, a combined weight of about 160lbs, a 500 pound test aircraft snapped like fishing line. Anyone else think we got jipped on 15' of cable?

Team 60 wench
 

We have designed a winch that is "attached" to one of the gear boxes. We will have then have a low (power) and high speed wench. I will post some pictures of it when we are done. I believe we are using stainless, boat cable. It's breaking point is at 1,200 lbs. We shall see if it all works in the next couple of days.

Shawn

Re: Winch
 

Here are two views of our winch

http://www.chiefdelphi.com/forums/pi...&quiet=Verbose

http://www.chiefdelphi.com/forums/pi...&quiet=Verbose

Re: Winch
 

All great ideas but what about using the drill motors for the winch?

Re: Winch
 

We have a winch built using the Tiagene Motor. We tested it out and our robot hangs almost completely level. It works WONDERFULLY. It has about a 500 lifting capacity, but CAUTION to other teams using this motor as a winch: Despite the fact that the motor utilizes a worm gear and lead screw and cannot be technically backdriven the drive shaft can and does slip inside of the worm gear. The shaft is not keyed and does slip causing the motor to backdrive. We are not using cable as most other team have discussed since it has to be stacked by a special sliding guide. Instead we are using winch strap which work better than cable. It has a 27,000LB. breaking load and stacks itself.