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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:
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Re: How many seconds to climb the rope?
This many: :deadhorse:
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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
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Re: How many seconds to climb the rope?
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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.
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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).
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Re: How many seconds to climb the rope?
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. |
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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.
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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.
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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.
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Re: How many seconds to climb the rope?
I feel like that will be the golden ticket for Regionals at least. ::ouch::
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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.
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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. |
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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.
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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 |
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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 |
Re: How many seconds to climb the rope?
15
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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.
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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.
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Re: How many seconds to climb the rope?
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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! |
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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* |
Re: How many seconds to climb the rope?
5920 is looking under 12 for Week 1 District.
Under 9 for Week 3 District, |
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.
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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. |
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.
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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. |
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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. |
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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. |
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Re: How many seconds to climb the rope?
Time to pony up and make it official. Go vote!
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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. |
Re: How many seconds to climb the rope?
Our robot this year is pretty darn lightweight. We plan on climbing in under 5 seconds.
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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). |
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.
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Re: How many seconds to climb the rope?
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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). |
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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). |
Re: How many seconds to climb the rope?
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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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