Robot climbing times

[Jared Russell]

Originally Posted by ENeyman

Most of the time, 341 would shoot the two preloads before getting the two from the bridge. However, when against another robot who went for the bridge in auton (27, 233), they would go to the bridge first, intentionally taking the penalty.

Also, 365 would take the additional ball in auton too.

To be clear, we always hoped not to take the penalty when we did this. A lot of the time, one or more balls would not happen to roll into our intake and we'd leave the bridge loaded with 3 balls. But sometimes all of them did. We were never carded for doing it, but on a couple of occasions people expressed some displeasure that we were setting up the bot to incur a foul.

What choice did we have though? Risk a 3 point penalty and then score 6 points with the extra ball (EV +3)? Or don't go for the bridge at all, and give our opponents 12 free points (EV -12)?

IMO, a game mechanic that makes it mathematically advantageous to just eat the penalty is (a) designed to be exploited and/or (b) poorly thought out.

[ToddF]

Running some quick numbers to put a lower bound on time:

Assume the simplest possible lifting method, winching yourself from the floor to the 90 inch bar straight vertically (yes, I know this is illegal). Power the winch by two CIM motors left over after using 4 in your drivetrain. To get max power from the motors, they run at 1/2 speed, producing 1/2 the stall torque.

For a CIM, stall torque is 21.5 in-lb and free speed is 5310 rpm.

Torque/Force used to select gear ratio:
Two CIMS running at max power produce 21.5 in-lb.
Assume a 1" diameter rod (smallest practical size, ish) to reel the cord onto.
At 1:1 gear ratio, line tension would be 43 lb.
For a 150 lb robot, need ~3.5:1 gear ratio.
Select motor pinions with 12 teeth engaging a winch gear of 40 teeth gives a robot weight of 143.3 lb

Gear ratio used to find lifting speed:
The CIMS are running at half speed = 2655 rpm
After the gear reduction, the winch speed is 796.5 rpm.
Multiplying by the rod circumferance and converting from minutes to seconds gives 41.7 inches/second.

So, with the most optimal lifting mechanism, operating at the optimal conditions, not accounting for acceleration and deceleration, lifting 80 inches, would take about 2 seconds.

[Andy A.]

Originally Posted by pandamonium

As long as it is under 2 minutes does time really matter?

Consistency... now that matters.

another factor is if the mechanism auto climbs or requires driver interaction.

4 seconds??? trolling???

Consistency absolutely matters, but time not spent climbing is time that can be spent scoring disks, transporting disks for an alliance partner, playing defense, or whatever else isn't related to climbing.

[Siri]

Originally Posted by ToddF

...Power the winch by two CIM motors left over after using 4 in your drivetrain...

Stupid questiin I guess -- What happens if you try the Simbotics-in-Breakaway route and use all 6 CIMS? Or do you just blow a breaker?

[45Auto]

For a CIM, stall torque is 21.5 in-lb

That is correct, for a CIM pulling 133 amps.

What kind of 40 amp circuit breakers are you using?

[Jared Russell]

Originally Posted by 45Auto

That is correct, for a CIM pulling 133 amps.

What kind of 40 amp circuit breakers are you using?

Which number matters for your application depends on how long you will be drawing the maximum current during the lift. You can pull 133 amps for a couple seconds without issue.

[ptkunapuli478]

Im assuming that you are accounting for the fact that you will be awarding the opposing alliance 6 points for carrying two more discs than the allotted 4

[JamesCH95]

Originally Posted by Siri

Stupid questiin I guess -- What happens if you try the Simbotics-in-Breakaway route and use all 6 CIMS? Or do you just blow a breaker?

The realistic power requirements to climb aren't that crazy for the motors we have available. Just for grins I calculated that using max power from two CIMs (~674W) a 150lb robot could be lifted 60in in 1.5s. Assuming a 50% drive loss that's still only 3s. So, unless you botch the gearing from 6 CIMs, I doubt there will be any issues.

I don't think that the power requirements are the challenge of climbing. The actual mechanism will be the challenging part (to state the obvious).

[Taylor]

Originally Posted by gabrielau23

Ridiculous. The only way I could see something even remotely close to this is if you dedicated your robot to climbing, in which case you made your robot a box on wheels and on which your bumpers and battery weigh more than the robot itself.

You say this like it's a bad thing.
2012 saw many alliance captains that could only balance on the bridge.

30 points in this game is nothing to sneeze at, and neither is the feat of designing a robot to do precisely the strategy you're belittling.

[mikegrundvig]

No one has posted a climbing idea like what one of our mentors proposed so I'll keep it under our hat for now until we get it prototyped. With that said, it's just dead clever. It would provide for a self-aligning, automatic climber that could get to the top in seconds. The math says just a couple of seconds, though I'm skeptical of that. I feel safe in saying if it works anything like intended, it will be less than 10 seconds for sure.

-Mike

[JesseK]

Originally Posted by IKE

If we assume that the 4 seconds is a goal:
150 Lb robot = 667 N
60 Inch=1.5 meters estimated change in CG height
Time = 4 sec
667N*1.5m/4 sec = 250 Watts.

Assuming 50-75% efficient mechanism your power draw would be:
333-500 Watts.
That is a lot of power draw, but not unheard of.

Add in the use of hybrid mechanisms (use pneumatics, motors & constant-force springs through the use of creative cabling) and the instantaneous electrical power requirement is greatly reduced.

[PVCpirate]

As far as holding extra game pieces goes, having an extra ball roll into the intake while shooting other balls is not very obvious, and could easily be missed by the refs. However, driving to the intake and having the human player feed 6 frisbees into the robot one at a time, then taking 30 seconds to climb up the pyramid with them will be extremely obvious. A robot that does this will definitely have the two fouls called against them, and doing it in several matches would likely draw a card at some point.

[TheOtherGuy]

Originally Posted by IKE

If we assume that the 4 seconds is a goal:
150 Lb robot = 667 N
60 Inch=1.5 meters estimated change in CG height
Time = 4 sec
667N*1.5m/4 sec = 250 Watts.

Assuming 50-75% efficient mechanism your power draw would be:
333-500 Watts.
That is a lot of power draw, but not unheard of.

I see that power all the time - in the drivetrain. Hmm...

[Siri]

Originally Posted by PVCpirate

As far as holding extra game pieces goes, having an extra ball roll into the intake while shooting other balls is not very obvious, and could easily be missed by the refs. However, driving to the intake and having the human player feed 6 frisbees into the robot one at a time, then taking 30 seconds to climb up the pyramid with them will be extremely obvious. A robot that does this will definitely have the two fouls called against them, and doing it in several matches would likely draw a card at some point.

Trust me, we saw it last year. Deliberate 4+ ball possession in autonomous was called at least twice at every event I coached or reffed, and sometimes more on the same team. The lack of carding last year* was not related to overlooking the illegal actions. It was no different than deliberately taking a Lane violation penalty in 2011 in order to complete a logo. As Jared said, it just makes sense.

*This post is not intended to provide direct insight into referee rulings for 2013. Hopefully the Q&A will inform this. If not, remember history, but (as always) execute entirely at your own risk.

[Paul Copioli]

Originally Posted by sanddrag

I disagree. It's completely possible. Not easy, but definitely possible.

OK, I am going to call it right now. No way is anyone under 5 seconds. In 2010, some of the best robots took 2 - 3 seconds using power take-off from the drive train.

All I can say is ... Nessy 2013 is the 4 second legal climb.