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-   -   How many seconds to climb the rope? (http://www.chiefdelphi.com/forums/showthread.php?t=154190)

norabaccam 24-01-2017 17:31

How many seconds to climb the rope?
 
My team has been working on our rope climbing mechanism, and we are curious of how many seconds of the 30-second time limit you guys think your robot will take to climb the rope :deadhorse:

liz.nelson.208 24-01-2017 17:40

Re: How many seconds to climb the rope?
 
This many: :deadhorse:

bearbot 24-01-2017 18:14

Re: How many seconds to climb the rope?
 
Right now we comfortable with 15 seconds but we're working on a faster method as right now.Our goal is between 5-10 seconds for CHS districts championship

frodobaggins05 24-01-2017 18:31

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by bearbot (Post 1635815)
Right now we comfortable with 15 seconds but we're working on a faster method as right now.Our goal is between 5-10 seconds for CHS districts championship

How did you get it to climb?

D_Price 24-01-2017 18:36

Re: How many seconds to climb the rope?
 
We are sitting right at about 9 seconds climbing but are looking to push it a little farther once everything is built into the robot.

Ari423 24-01-2017 19:10

Re: How many seconds to climb the rope?
 
Are we talking about just time spent physically moving up the rope or including time to align? It will probably take use a good 20+ seconds to line up and climb, but the actual climb should only take ~4 seconds (according to the JVN calc).

Richard Wallace 24-01-2017 19:33

Re: How many seconds to climb the rope?
 
  • The touch pad is 58 inches from the floor.
  • A robot attaching to the rope 23 inches from the floor must raise itself 35 inches to reach the touch pad.
  • The energy required to raise a 150 lb robot 35 inches is about 600 Joule.
  • One CIM motor can operate at >300 Watt output power for a few seconds.
  • => Two CIM motors can deliver 600 Joule in about one second.

If mechanical efficiency is high enough, a climbing mechanism powered by two CIM motors can complete the lift in about one second, after the attaching to the rope. Some mechanisms might be made even faster, by attaching to the rope at a greater initial height.

Time required to reach the rope and attach will be the limiting factor on how many seconds a drive coach will need to allow at the end of a match.

norabaccam 24-01-2017 19:52

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Ari423 (Post 1635847)
Are we talking about just time spent physically moving up the rope or including time to align? It will probably take use a good 20+ seconds to line up and climb, but the actual climb should only take ~4 seconds (according to the JVN calc).

Talking about the actual climb. My team was planning to climb the rope definitely under 10 seconds, and I agree that lining up may take a while.

cad321 24-01-2017 22:18

Re: How many seconds to climb the rope?
 
We're currently climbing in ~6 seconds. Hopefully a little less by the end of the build.

MrForbes 24-01-2017 23:46

Re: How many seconds to climb the rope?
 
we plan on about 5 seconds for a climb. We'll see what happens...still figuring out what the robot will weigh. I think today's test with a light robot simulator was less than 5 seconds.

OMGRobots1 25-01-2017 00:47

Re: How many seconds to climb the rope?
 
We tested on a ~40 pound robot, and it was well under 5 seconds, probably around 3. We intend to keep it under 5 seconds on the real robot.

D_Price 25-01-2017 01:47

Re: How many seconds to climb the rope?
 
I feel like that will be the golden ticket for Regionals at least. ::ouch::

Quote:

Originally Posted by OMGRobots1 (Post 1635996)
We tested on a ~40 pound robot, and it was well under 5 seconds, probably around 3. We intend to keep it under 5 seconds on the real robot.


Basel A 25-01-2017 01:55

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Richard Wallace (Post 1635855)
  • The touch pad is 58 inches from the floor.
  • A robot attaching to the rope 23 inches from the floor must raise itself 35 inches to reach the touch pad.
  • The energy required to raise a 150 lb robot 35 inches is about 600 Joule.
  • One CIM motor can operate at >300 Watt output power for a few seconds.
  • => Two CIM motors can deliver 600 Joule in about one second.

If mechanical efficiency is high enough, a climbing mechanism powered by two CIM motors can complete the lift in about one second, after the attaching to the rope. Some mechanisms might be made even faster, by attaching to the rope at a greater initial height.

Time required to reach the rope and attach will be the limiting factor on how many seconds a drive coach will need to allow at the end of a match.

Yep. Why climb slow when you can climb fast?

pmattin5459 25-01-2017 04:33

Re: How many seconds to climb the rope?
 
I think that the goal is less than 5 seconds for a relatively light 'bot. Alignment might take more time, depending on how well the mechanism grabs on to the rope, but there are so many different ways to attach onto a rope that it'll be relatively easy to find an optimal solution.

GeeTwo 25-01-2017 07:41

Re: How many seconds to climb the rope?
 
I saw a post where a team is using a single BAG and expects a 4 second climb. With proper gearing and level winding, the numbers make sense.

When you plan your start time, don't forget to account for the one-second hold - you need to be depressing the touchpad by T=1.

cad321 25-01-2017 07:55

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by GeeTwo (Post 1636032)
When you plan your start time, don't forget to account for the one-second hold - you need to be depressing the touchpad by T=1.

Don't forget though that this 1 second doesn't have to be entirely during teleop. As long as you start while still in teleop (even say in the last 0.1 second) you still get the 50 points as long as you've held it for that whole 1 seconds.

tr6scott 25-01-2017 08:14

Re: How many seconds to climb the rope?
 
1 Attachment(s)
Quote:

Originally Posted by cad321 (Post 1636035)
Don't forget though that this 1 second doesn't have to be entirely during teleop. As long as you start while still in teleop (even say in the last 0.1 second) you still get the 50 points as long as you've held it for that whole 1 seconds.

Correct. See 5th option from top of the graph in game manual.

qscgy 25-01-2017 08:16

Re: How many seconds to climb the rope?
 
When we set the rope properly, it takes about 7 seconds to lift 150 pounds using a Mini CIM and a 50:1 VersaPlanetary.

bobbysq 30-01-2017 20:13

Re: How many seconds to climb the rope?
 
Here's a test with a 100:1 VP and a 775pro on our 2016 robot (nearly at the weight limit)

https://www.youtube.com/watch?v=VyNp-fGKJDk

IceStorm 30-01-2017 20:27

Quote:

Originally Posted by bobbysq (Post 1638405)
Here's a test with a 100:1 VP and a 775pro on our 2016 robot (nearly at the weight limit)



https://www.youtube.com/watch?v=VyNp-fGKJDk



Did you have any other gearing or just the775pro into the 100:1 VP? That's what we're thinking of doing.


Sent from my iPhone using Tapatalk Pro

Boltman 30-01-2017 20:37

Re: How many seconds to climb the rope?
 
15

Hgree56 30-01-2017 20:38

Re: How many seconds to climb the rope?
 
Our team agreed to not go into much details, but after dozens of tests over the past week, our slowest climb was 11 seconds and our fasts was tonight at 3 seconds. We are averaging around ~4.5 seconds.

bEdhEd 30-01-2017 20:42

Re: How many seconds to climb the rope?
 
Considering that our climber is powered by two miniCIMs with a gearing of 100:1 and the possible weight of our bot, I think the students calculated something around 4 seconds. The final component still needs to get built, so we'll see if our testing shows us a potential climb of less than or greater than 4 seconds.

bobbysq 30-01-2017 20:51

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by IceStorm (Post 1638409)
Did you have any other gearing or just the775pro into the 100:1 VP? That's what we're thinking of doing.


Sent from my iPhone using Tapatalk Pro

We had no other gearing, other than a 1:1 chain that was a holdover from its days as an intake.

s_forbes 30-01-2017 21:32

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by bobbysq (Post 1638405)
Here's a test with a 100:1 VP and a 775pro on our 2016 robot (nearly at the weight limit)

https://www.youtube.com/watch?v=VyNp-fGKJDk

Thanks for posting test footage!

What is the diameter of that spool that the strap is winding around? Also it sounds like you have some kind of speed control on the motor, have you tried going 100% throttle as it climbs up?

With a 100:1 reduction on a 775 and a full weight robot, you'll start to draw more than 40 amps when you're spool reaches about 2.5" in diameter (which is kind of the limiting factor with the breakers, but they won't pop immediately if you go over 40 amps). With that size of spool it should take just over 2 seconds to span the distance from the top of the robot to the davit.

As you make the spool smaller in diameter, the motor will draw less current (you're electronics system will be happier) but your climb will be slower.

Be careful not to let the magic smoke out of the motor!

pmattin5459 30-01-2017 22:44

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Boltman (Post 1638410)
15

15? What gearing and motors are you using? That seems like a rather long period of time, and you have to also leave time to catch onto the rope. I would suggest getting your time a little bit lower, perhaps under 10.

Trevor1523 30-01-2017 22:55

Re: How many seconds to climb the rope?
 
We vary between about 6 and 8 seconds, using a big ol' CIM motor. Overbuild and add complexity!

Those teams that use Bag motors to climb scare me. *shudders*

VIKotic Dave 31-01-2017 01:42

Re: How many seconds to climb the rope?
 
5920 is looking under 12 for Week 1 District.
Under 9 for Week 3 District,

Thayer McCollum 31-01-2017 09:31

Re: How many seconds to climb the rope?
 
According to our calculations, using a CIM with a 64:1 BB220 gearbox, and assuming a 150 lb robot (this includes bumpers and battery) we should be able to climb in ~4 seconds. Given that it'll take a little bit to line up I expect that we'll be able to get the 50 points if we start the attempt with 15 seconds remaining in the match.

6101 Robert 31-01-2017 09:44

Re: How many seconds to climb the rope?
 
I think why you are seeing such long climb times is that you are not properly gearing your CIM/mini-CIM motor. Remember that a motor's maximum power output (watts) is usually roughly around 50% load. Not accounting for friction and other factors, one should be able to climb in 2-3 seconds with only a mini-CIM -- at least according to our calculations.

For reference, we are using a 1 3/4" winch with a 20:1 gearbox and a mini-CIM. If this isn't fast enough, we can easily upgrade to a full CIM.

MrForbes 31-01-2017 09:48

Re: How many seconds to climb the rope?
 
I guess there are a couple different ways to look at what is "proper gearing". If you design it so the motor has to run at maximum power, then you don't have much of a safety margin. If you design it so the motor runs at maximum efficiency, then you will still be able to climb at maximum power when things go wonky...like a low battery at the end of the match, more friction than you anticipated, etc.

Chris is me 31-01-2017 10:26

Re: How many seconds to climb the rope?
 
I don't think the number of seconds from "secured the rope but haven't left the ground yet" to "up in the air pressing the button" is particularly important. The time from starting the entire rope climbing process to the end of it, somewhat.

I don't think it's the worst thing in the world to have a climber that takes a couple seconds to get up there, but ideally your entire climb cycle should be under 10 seconds at least.

Gear your climber conservatively. Max power for these motors is usually well over 40 amps and leaves little margin for error or for your breakers to not trip. You also have to consider you are climbing when your battery voltage is at its lowest.

Ari423 31-01-2017 10:55

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Chris is me (Post 1638581)
Max power for these motors is usually well over 40 amps and leaves little margin for error or for your breakers to not trip.

I'm going to go ahead and disagree with this statement. I just did the math and the only two motors that are over the 54A limit that a 40A breaker can provide indefinitely at max power are the CIM and 775pro. Both of these draw about 65A. For all other motors, you can run them at max power (i.e. 50% free speed) indefinitely on a 40A breaker. The BB-RS775 is close at 50A, but I wouldn't be worried too much because the breakers don't trip immediately, they take a few seconds, especially when the current is only slightly over the limit.

Those three exceptions aside, you can run all of the other motors at max power without really worrying about tripping breakers. Whether you actually want to depends a lot on how big of a FoS you want and what options you have as far as motor choice.

Chris is me 31-01-2017 11:10

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Ari423 (Post 1638598)
I'm going to go ahead and disagree with this statement. I just did the math and the only two motors that are over the 54A limit that a 40A breaker can provide indefinitely at max power are the CIM and 775pro. Both of these draw about 65A.

54A is on the very outer edge of the current breaker tolerance band; I would not rely on your mechanism being able to consistently pull exactly 54 amps. If you have a slightly out of spec breaker, or your mechanism has marginally more load than you expect (various ineffiencies, etc), you'll have a bad time, especially since that doesn't even factor in voltage drop. It is reckless to give people the general advice that they should expect and plan for their motors to draw 54 amps under design load.

With that all said, the other motors with max power drawn at more than 40 amps include the mini-CIM, BB-775, BB-550, etc. Basically, any motor you should be climbing with.

The other danger with gearing at exactly mass power is that once you tip over that critical point, you're getting less and less efficient performance out of your motor as your load increases.

You also don't want to run fan-cooled motors at 50% stall generally; it's not great for them to run that hot. Be conservative here; you're not going to win the World Championship with a climb that's 300ms faster than your opponent if your motors smoke.

There's some benefit to climbing quickly, to a point, but this isn't a race, and you just want to complete it reasonably quickly. You can easily get there with 1 CIM / 775pro geared conservatively for less than 40 amps under load - add a second if you really want those sub-2s climbs; don't overwork 1 motor.

bobbysq 31-01-2017 11:19

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by s_forbes (Post 1638429)
What is the diameter of that spool that the strap is winding around? Also it sounds like you have some kind of speed control on the motor, have you tried going 100% throttle as it climbs up?

With a 100:1 reduction on a 775 and a full weight robot, you'll start to draw more than 40 amps when you're spool reaches about 2.5" in diameter (which is kind of the limiting factor with the breakers, but they won't pop immediately if you go over 40 amps). With that size of spool it should take just over 2 seconds to span the distance from the top of the robot to the davit.

I believe we weren't gunning it, but we were going maybe 80%-90% speed. The tube was a PVC pipe around 1.5" in diameter. Our test rig actually used an ATC fuse box, so it only had a 30A breaker and we were surprisingly able to stall it for a little while. The full robot will probably use a 40 amp breaker though.

JesseK 31-01-2017 11:21

Re: How many seconds to climb the rope?
 
Time to pony up and make it official. Go vote!

Ari423 31-01-2017 11:38

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Chris is me (Post 1638609)
54A is on the very outer edge of the current breaker tolerance band; I would not rely on your mechanism being able to consistently pull exactly 54 amps. If you have a slightly out of spec breaker, or your mechanism has marginally more load than you expect (various ineffiencies, etc), you'll have a bad time, especially since that doesn't even factor in voltage drop. It is reckless to give people the general advice that they should expect and plan for their motors to draw 54 amps under design load.

With that all said, the other motors with max power drawn at more than 40 amps include the mini-CIM, BB-775, BB-550, etc. Basically, any motor you should be climbing with.

The other danger with gearing at exactly mass power is that once you tip over that critical point, you're getting less and less efficient performance out of your motor as your load increases.

You also don't want to run fan-cooled motors at 50% stall generally; it's not great for them to run that hot. Be conservative here; you're not going to win the World Championship with a climb that's 300ms faster than your opponent if your motors smoke.

There's some benefit to climbing quickly, to a point, but this isn't a race, and you just want to complete it reasonably quickly. You can easily get there with 1 CIM / 775pro geared conservatively for less than 40 amps under load - add a second if you really want those sub-2s climbs; don't overwork 1 motor.

When I'm designing mechanisms I like to use all of the edge case values and incorporate my FoS into the load. For that (especially with climbs not taking longer than 6s) I would use 54A and make sure to include a significant FoS in my load. If you do it differently, that's fine.

I agree with pretty much everything you are saying; my team's climber is powered by 2 BAGs which gives us plenty of power and the ability to add more if needed by switching to a different dual-motor VP input. That being said, while I agree a blanket statement saying you can run all the other motors at max power probably wasn't the best idea, a blanket statement that you shouldn't run any of them at max power isn't really called for either. I'd be interested in seeing data about running fan-cooled motors at half speed. There are a lot of factors here that need to be considered on a case by case basis imo.

Gravity 31-01-2017 12:15

Re: How many seconds to climb the rope?
 
Our robot this year is pretty darn lightweight. We plan on climbing in under 5 seconds.

Chris is me 31-01-2017 12:33

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by Ari423 (Post 1638621)
That being said, while I agree a blanket statement saying you can run all the other motors at max power probably wasn't the best idea, a blanket statement that you shouldn't run any of them at max power isn't really called for either. I'd be interested in seeing data about running fan-cooled motors at half speed. There are a lot of factors here that need to be considered on a case by case basis imo.

One blanket statement results in people tripping breakers or damaging motors. The other results in reliable mechanisms that err on the side of too conservative. I don't think they're really equivalent.

BAGs are an interesting case here; they should be more durable than fan cooled motors and stall at like 75 amps or so. I just assumed people would go for more mechanical power if they are interested in optimal solutions (you can do a 775pro / CIM / mini at less-than-max power that outperforms a BAG even on a less ideal point on its motor curve).

qscgy 31-01-2017 21:44

Re: How many seconds to climb the rope?
 
The mean of the poll responses seems to be 3-6 seconds. Now I feel bad about our 8 second climb. Of course, from what I've seen, most climbers have CIMs. We are using a single Mini CIM with a 50:1 VersaPlanetary, although we have space to put 2 in a 2-CIM VersaPlanetary mounting if those few seconds look like they will make a significant difference.

JesseK 31-01-2017 23:32

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by qscgy (Post 1638860)
The mean of the poll responses seems to be 3-6 seconds. Now I feel bad about our 8 second climb. Of course, from what I've seen, most climbers have CIMs. We are using a single Mini CIM with a 50:1 VersaPlanetary, although we have space to put 2 in a 2-CIM VersaPlanetary mounting if those few seconds look like they will make a significant difference.

There are many factors that go into climber design, including how much space and power you can allocate it. If it goes up every match in 8 seconds, I'm sure you'll find a valuable home on an alliance.

If climb time is still a concern, then you may be able to replace the MiniCIM with a 775Pro through a VP CIM-ile and adjust your gearing slightly.

Yet in our testing, it is time to line up and time for the rope to catch that actually takes the longest. From liftoff to touchpad ours is under 2 seconds. Yet from rope touch to rope engagement it's about another 2 seconds. There are still a couple of things we can do to minimize it further, but our target is under 4 seconds (place gear at 5 seconds remaining).

Chris is me 01-02-2017 09:52

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by qscgy (Post 1638860)
The mean of the poll responses seems to be 3-6 seconds. Now I feel bad about our 8 second climb. Of course, from what I've seen, most climbers have CIMs. We are using a single Mini CIM with a 50:1 VersaPlanetary, although we have space to put 2 in a 2-CIM VersaPlanetary mounting if those few seconds look like they will make a significant difference.

I just want to let you know that if you're referring to the 2-motor VersaPlanetary adapter, that adapter is not compatible with the mini-CIM as the motor is much larger than what the adapter is designed for. If you are actually referring to the BAG motor instead of the mini-CIM, then the adapter will work with that.

I don't think a fast climb is incredibly important at all levels of play this year; a consistent climb is far more valuable if that's the tradeoff you're making. Since you're using a VP, you can always try a smaller reduction later if you want, such as 40:1, and see if the motor still does a good job lifting with that amount of torque. (I don't know if it will, I'm just throwing it out there).

Hgree56 01-02-2017 10:31

Re: How many seconds to climb the rope?
 
Quote:

Originally Posted by qscgy (Post 1638860)
Of course, from what I've seen, most climbers have CIMs. We are using a single Mini CIM with a 50:1 VersaPlanetary, although we have space to put 2 in a 2-CIM VersaPlanetary mounting if those few seconds look like they will make a significant difference.

Our team is using miniCIMs also. Granted, we are using three, but it's a 10.71:1 gear box. We are getting a ~4.5 second climb consistently.

scott.smith 01-02-2017 10:53

Re: How many seconds to climb the rope?
 
We are using a PTO, so we are looking at 1 second for climb once it grabs on.


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