Showing You're Under 10ft/s

[Yan Wang]

Ken, that's if you're on the floor. The distance from the topmost platform to the bar is only 9'. So from that to the bar would have to be <=0.9s.

Also, I understand that it'd be easy to have a stopwatch on hand in the pits to time the sequence with the inspectors watching, but what about instantaneous velocities? Does FIRST only care about avg velocities? That's what I'm wondering about - because that would be highly frustrating to document [instantaneous].

[KenWittlief]

If your arm move less than ten feet in 2 seconds you are going to be ok - you can reason out the start and end speeds if you measure the average.

remember the reason behind this rule is safety - its not to hard to observe a device in action and conclude that its going to hurt someone, or that its safe.

[NoRemorse]

I don't think the rule is really meant to be about arms, but about projectiles. I could be wrong

[dlavery]

Originally Posted by NoRemorse

I don't think the rule is really meant to be about arms, but about projectiles. I could be wrong

The rule applies to ANY mechanism that engages the chin-up bar. It doesn't matter if it is an arm, projective, spear, grappling hook, or string of spaghetti.

-dave

[Travis Covington]

Originally Posted by dlavery

The rule applies to ANY mechanism that engages the chin-up bar. It doesn't matter if it is an arm, projective, spear, grappling hook, or string of spaghetti.

-dave

Now what if this bar grabbing device is an elevator, constrained at the bottom and top (with guides so it can only move upward XX feet). Does the 10fps rule apply here too? Another example would be a pneumatic device (using a piston) that extended upward toward the bar, a smaller piston (3/4" bore) definitely can move faster than 10fps, is this devices speed restricted as well?

The way I read it, I have a hard time applying the rule to objects other than projectiles. Using the spirit of the rules, I could imagine why an arm moving faster than 10fps could be dangerous, however, I do not see it being as lethal as something that is released into the air (such as a grappling hook) and could potentially hit spectators/drivers/people. Although there are some exceptions, most 'contstrained' devices pose a lesser risk than some sort of projectile.

Point me in the right direction, this might be problematic to some teams at competition (including ours).

[KenWittlief]

Dave already pointed you :c)

the end of any device designed to capture or latch onto the bar cannot move faster than 10 feet per second.

a hook or pole that extends faster than that would be dangerous to anyone standing near it when it goes off - on the field setting up the bot, or working on the machine in the pits, doing a demo for people in the pits, standing in the queue waiting for your match to start...

[Stephen Kowski]

Originally Posted by KenWittlief

a hook or pole that extends faster than that....

Originally Posted by KenWittlief

if your bot reaches up and grabs the bar in less than 1 second....

is the 10 f/s rule only considered with vertical velocity? just trying to clear this in my mind....thx

[russell]

Yeah we have an arm that pivots. Does that mean that if the tip of the arm rotates from near the floor up to the bar in more than 1 second we are OK? Because it travels more than 10 feet.

[Joe Ross]

Since there seems to be some confusion about the rule, here it is:

<G08> Mechanisms which interact with the Pull-Up Bar are limited to a maximum tip velocity (relative to the ROBOT) of 10 feet per second.

Mechanisms means anything, arm, projectile, etc. And it isn't just the vertical velocity. It is the tip velocity. For example, our arm rotates approximately 180 degrees with a 5 foot radius. It takes just over 3 seconds to do that. So, our average velocity is just over 5 ft/sec. I am hoping that is enough margin that we won't have to "prove" the speed. If you calculate that you are closer to 10ft/sec then you should be prepared to prove the speed, such as in

<R82> During inspection, teams must be able to demonstrate the operation of any robot mechanism intended to interact with the Pull-up Bar on the center structure on the field, and show that its tip velocity complies with the 10 feet/ second velocity maximum limit requirement. One way that this may be accomplished is by recording the tips motion with a camcorder with a known frame rate (to provide delta time) against a measuring tape background reference (to provide delta distance).

Yan, use common sense with the average vs instantaneous measurments. If one part of your movement is much much faster then the rest, you should be prepared to show that in that part it isn't more then 10 ft/sec. However, if by your eye you can see that it has a fairly constant speed, then average speed would be perfectly acceptable.

Of course, I am not the official answer. If you really have concerns about your method of documentation, then ask on the FIRST Q/A.

[Travis Covington]

Hmm... I do remember reading that and worrying... I guess I overlooked our individual circumstance. It is easily fixable, so no problems.

Thanks for the help.