pic: Possibly Useful Contraption

[Richard Wallace]

Originally Posted by Andy Baker

This is a simple and elegant application.

At this ratio, a 90 degree arm movement would take about 8 seconds. If the torque was cut in half and the speed doubled, then a 90 degree motion would take 4 seconds. This faster speed is probably more in comparable with arm movements during recent FIRST games (04, 05).

If I recall correctly, the 2005 TechnoKat robot's arm (along with many of the winning teams) had about 120 degrees of movement in under 2 seconds.

Thanks, Andy. You make an important point that faster action might well be needed; such a requirement might push beyond the power range in which a Globe can be effective. I was thinking about possible heavy lifting or short-throw, high-load applications.

When the throw is longer and the load is lighter, a modified Globe with about 450 RPM free speed might work well in a similar configuration -- possibly using plastic sprockets and chain. In applications requiring both longer throw and high loads (such as the 2005 arm) someone might use a FP/NBD or FP/BaneBots gear-motor solution instead of the Globe. Or they might use a CIM motor fitted to an AndyMark planetary. Or if space permits they might use a pneumatic cylinder.

Of course FRC teams have used many other stock and custom gear-motor solutions. And if FIRST stays true to form, there will be even more options next year.