Lock and hanging

When we hang our robot, it will go up and then the motor will reverse and bring it back down. At the VA competition we saw people hanging and staying up in the air even after the judges cut the power to the robots, how do you keep it hanging. (might be a stupid question)

You need a stronger gear ratio with more torque then even if the motor has no power there is not enough strength in the joint to backup the motor

Instead of relying on a de-energized motor’s resistance to turning some folks build a simple latch.

One way to make the latch is to use a ratchet and pawl type of mechanism (http://www.fi.edu/time/Journey/Time/Escapements/clktogether.html) ([http://kmoddl.library.cornell.edu/model.php?m=247)

Your pawl can be held in place passively by gravity, rubber bands, or the springiness of a peice of flexed metal; or you can use a servo/motor to actively engage (and perhaps disengage) the pawl.

There are other types of latching mechansisms you can use. Ratchets are just one.

Using either the motor resistance approach or the a latching mechanisim of some sort, you Spotsy guys are clever enough that you should be able to carry the ball the rest of the way to the goal line from here.

Blake
PS: The second URL above takes you into Cornell’s way-cool library of “mechanisms”. Spending an hour or two browsing through there would be time well spent for anyone on an FVC or FRC team…](http://kmoddl.library.cornell.edu/model.php?m=247))

the link you gave me does not work, but thanks though.

i would definetly say to go with a big gear train with lots of torque.

~Alex~

The problem with a ratchet is that the arm is thatit must go both ways and there is a reason but I won’t say what it is. I think a much stronger gear ratio is all we need.

Fixed the URLs. The forum editor had mashed the two of them together as if they were a single URL.

Lower gear ratios will allow the de-energized motor (or one fed a 127 PWM command) to support a large mass; they will also slow down the motion of the extender.

I look forward to seeing what you choose. Will it be unveiled at the GFHS Scrimmage on the 20th?

Blake

I look forward to seeing what you choose. Will it be unveiled at the GFHS Scrimmage on the 20th?

Blake

yes our team plans on being at the scrimmage on the 20th

yes our team plans on being at the scrimmage on the 20th

We’ll try our hardest to be there, clunker or beast.:smiley: