3rd level climb even possible?

[Peter Matteson]

Originally Posted by F22Rapture

How would you implement a pneumatic climber? I could definitely see using pneumatics to actuate claws, but aren't they mostly useful for pushing and not pulling, as the majority of the movement in the climb would be?

They can be used to drive linkages that lift the entire robot.

This really isn't that tough to design, the biggest issue is the weight of the cylinders and the volume of air needed to drive the system, However I haven't put too much thought into it yet but I'm sure it can be done.

[pfreivald]

Originally Posted by Peter Matteson

They can be used to drive linkages that lift the entire robot.

This really isn't that tough to design, the biggest issue is the weight of the cylinders and the volume of air needed to drive the system, However I haven't put too much thought into it yet but I'm sure it can be done.

My math on the air charge needed makes a linear pneumatic system untenable. Combined with other mechanisms it becomes much more viable.

[SciBorg Dave]

Is the 30 point climb worth the effort. I think we will see teams do the 30 point climb on the first weekend of the regionals. I also think we will see teams fall from 3 to 5 feet and distroy their robot for the weekend. It is easy to do a 10 point climb with the only problem to worry about is a robot falling on you from above. I think the climb is not the game changer, the changer is getting the 6 disc in the top of the pyramid (30 points). I do not think that the 30 point climb is worth the effort if it DOES NOT takes away from your shooting abilities.

[ablatner]

Looking back at 2010, battery power really isn't a problem.

[pfreivald]

Originally Posted by ablatner

Looking back at 2010, battery power really isn't a problem.

Are you sure? Two feet isn't six.

[Grim Tuesday]

Originally Posted by pfreivald

Are you sure? Two feet isn't six.

Not only battery power but I'm especially worried about teams who plan to use pneumatic power. There are only so many tanks you can strap onto your robot.

[pfreivald]

Originally Posted by Grim Tuesday

Not only battery power but I'm especially worried about teams who plan to use pneumatic power. There are only so many tanks you can strap onto your robot.

Unassisted pneumatics are not a viable solution, to be sure.

[StevenB]

Run out of battery power? No way.
Let's do some math:

150 lbs ~= 70 kg
Assume you want to raise your robot 2 meters (78 inches)
PE = m*g*h = 70 kg * 9.8 m/s^2 * 2 = 1400 Joules

The battery has an 18 Amp-hour capacity (although you don't this much out of it in practice).

18 Ah * 12 V = 18 * 12 * 3600 Volts*Amps*seconds = 78 kJ

So climbing would use just under 2% of your battery power.

Or, looked at another way, let's assume your robot has a maximum speed of 4 meters per second (13 feet/second). To accelerate to top speed requires

KE = 1/2 * m * v^2 = 1/2 * 70 kg * (4 m/s) ^ 2 = 560 Joules

So, if we pretend that all our mechanisms are frictionless and 100% efficient, sprinting from one side of the field to the other three times is very roughly equivalent to climbing the tower.

Originally Posted by F22Rapture

I could definitely see using pneumatics to actuate claws, but aren't they mostly useful for pushing and not pulling, as the majority of the movement in the climb would be?

No. In fact, I've heard it argued that you should always use pneumatics to pull, rather than push, because that way you don't put the rod into compression and risk bending it.

[pfreivald]

Originally Posted by StevenB

Run out of battery power? No way.

After an entire match of compressor running, pushing/shoving, shooting, etc, etc?

Entirely possible to not have the oomph necessary to do what was designed to be done at "12V"*, especially if the design doesn't compensate for the drop in available voltage after ~90 seconds or so of a match.


*Likely more, as 12V batteries aren't, well, 12V.

[StevenB]

Yes, it's possible to kill your battery, and designing your climbing system for a fresh battery is unwise. But it's pretty rare that robots can't still drive across the field by the end of the match. Power-wise, climbing isn't actually any worse than driving around.

[dellagd]

Originally Posted by StevenB

Yes, it's possible to kill your battery, and designing your climbing system for a fresh battery is unwise. But it's pretty rare that robots can't still drive across the field by the end of the match. Power-wise, climbing isn't actually any worse than driving around.

Yep. We're climbing to the third with only two FP motors right now (I think they're illegal, but its just for the prototype as of now)

[karomata]

It is very possible, but also very hard. That's why its worth 30 points, so that teams will actually attempt it.

[Daniel_LaFleur]

Originally Posted by StevenB

No. In fact, I've heard it argued that you should always use pneumatics to pull, rather than push, because that way you don't put the rod into compression and risk bending it.

Steven,

Keeping the rod in tension rather than compression is a good idea, but you should actually do the bending calculations before ruling out pushing with a cylinder. Most cylindars are designed so that their rods can handle max force the cylindar can produce in compression. Rods are typically destroyed by side loads.

Also cylinders usually have more push force than pull force due to the area taken up by the rod.