How Fast Can you Safely Climb?

[Ginger Power]

There are going to be some extremely fast climbers this year. How fast can you reasonably climb without putting the Pilots, the field, and your robot in danger?

For example, say a team can climb in 1 second. Their robot is going to be traveling very fast... they are going to hit the field sensor very hard... how much abuse can the field take?

[RoboChair]

Originally Posted by Ginger Power

...how much abuse can the field take?

Never enough.

Looking at you Team 900....

[Daniel_LaFleur]

Originally Posted by RoboChair

Never enough.

Looking at you Team 900....

QFT.

I'm even more concerned hen the winch doesn't stop at the top of the climb

[Joseph Smith]

I could see a team that runs into the touchpad and continues running their winch until one of two things happens:
They burn out their motors

OR

Their gearing is reduced enough that they yank the retaining knot of their rope through the davit and fall to the ground.

Teams should plan on having a way to stop climbing when they reach the top that doesn't consist of stalling motors.

[Bruceb]

ok I am not a programmer but isn't there a way to sense current draw and shut the motors off when it spikes?

[Eric Scheuing]

Originally Posted by Bruceb

ok I am not a programmer but isn't there a way to sense current draw and shut the motors off when it spikes?

The answer is yes, but you want to do this as a backup, not as a primary stop feature. I say this as a team that used this method last year, and was having anxiety attacks all season about burning out that motor.

[JesseK]

Originally Posted by Eric Scheuing

The answer is yes, but you want to do this as a backup, not as a primary stop feature. I say this as a team that used this method last year, and was having anxiety attacks all season about burning out that motor.

Different anecdote:

The only sensors 1538 added to their bot for the 2015 season were encoders. They used current sensing for limits. Even with all of its complexity, this is what their wiring looked like.

It takes time to develop current-based limits. They don't work if a team decides to try them out for the first time on the robot in week 6.

[dirtbikerxz]

Just have the drivers stop pushing the "climb" button, when the bot slams into the touchpad. Since climbers this year (most likely) will only have to be turning in one direction, a simple solution to avoiding having to stall the motors to stay up is just sticking a ratcheting socket wrench on the end of the climber shaft. That should keep the bot from coming back down without having to stall the motors.

[MrForbes]

When I read the rules, it appeared that if your robot contacts the touchpad, but then goes back down the rope enough that the touchpad is no longer activated, then you can't get the climbing bonus.

It might be that you want to spend a little time on the control system for your climbing mechanism?

[Chris is me]

Originally Posted by MrForbes

When I read the rules, it appeared that if your robot contacts the touchpad, but then goes back down the rope enough that the touchpad is no longer activated, then you can't get the climbing bonus.

It might be that you want to spend a little time on the control system for your climbing mechanism?

This isn't a universally true statement. You just need to satisfy the two criteria:

1. Touch the pad for at least 1 continuous second
2. Touch the pad during the 0.0 second mark on the clock.

I actually can't find anything in the rules that suggests that these two operations have to be done in the same instance of touching the button; I could have missed that though. Point being, if you touch the button at zero seconds, and you've already touched it for 1 second or more beforehand, you don't need to stay up there.

Any number of really simple control system things can ensure you don't immediately fall back down once you touch the button - it could be as simple as a feed-forward gain.

[Basel A]

Originally Posted by Chris is me

This isn't a universally true statement. You just need to satisfy the two criteria:

1. Touch the pad for at least 1 continuous second
2. Touch the pad during the 0.0 second mark on the clock.

I actually can't find anything in the rules that suggests that these two operations have to be done in the same instance of touching the button; I could have missed that though. Point being, if you touch the button at zero seconds, and you've already touched it for 1 second or more beforehand, you don't need to stay up there.

Any number of really simple control system things can ensure you don't immediately fall back down once you touch the button - it could be as simple as a feed-forward gain.

That would be a good question for the Q&A. I would anticipate that it does have to be the same instance but as you say, that's not specified.

As for control, the easiest way is to (a) press the touchpad using something springy like a bumper and (b) have something mechanical like a ratchet keeping you from moving downward. This combination means you can stop all power but will still be exerting some small amount of force on the touchpad.

[Ginger Power]

Originally Posted by Joseph Smith

I could see a team that runs into the touchpad and continues running their winch until one of two things happens:
They burn out their motors

OR

Their gearing is reduced enough that they yank the retaining knot of their rope through the davit and fall to the ground.

Teams should plan on having a way to stop climbing when they reach the top that doesn't consist of stalling motors.

What happens when the retaining knot is solid, the gear ratios are low, and the rope is rated to ridiculous tensile strengths? Is there a realistic possibility that something on the field could break?

What recommendations do people have so teams

1. Don't burn out climber motors
2. Don't break the field

[Joseph Smith]

Originally Posted by Ginger Power

What happens when the retaining knot is solid, the gear ratios are low, and the rope is rated to ridiculous tensile strengths? Is there a realistic possibility that something on the field could break?

What recommendations do people have so teams

1. Don't burn out climber motors
2. Don't break the field

As Bruceb noted, you could have some way to detect a spike in current that the climb motor is drawing, and use this as a trigger to stop running the motor. (I'm not a programmer, but I know that the control system lets you monitor current outputs.) Or, you could set up a system where there is a flexible plate over a limit switch, such that when it is pushed against the touch sensor the plate will bend down and trip the limit switch. This way it could apply the required force to activate the sensor, but stop you from trying to tear the airship apart.

[Chris is me]

You know, the rope and target are one of the few things on the field you can be reasonably sure you'll be able to see. Just have the operator stop hitting the "winch up" button.

[prozack19]

Originally Posted by Chris is me

You know, the rope and target are one of the few things on the field you can be reasonably sure you'll be able to see. Just have the operator stop hitting the "winch up" button.

I was literally thinking the same thing.