Globe motor backdrive!!

[Greg McCoy]

Originally Posted by KevinB

Yea we have problems with Globe motor backdrive ... Setting the speed controller to break mode doesn't help.

I think that setting our Globe motor Victors to brake did help keep our arm's wrist from "drooping" back down when the control was at neutral. There might not be enough "brake" for a robot-lifting application though...

[Phil_Lutz]

We are using a bolt attached thru the winch drum.
This bolt is stopped by a metal bar which is actuated by a servo and tensioned by a spring.

Here we go.
Before applying power (speed) to our winch motor, programmatically we move a servo which moves the steel bar out of the way of the bolt. The steel bar is tensioned with a spring. When the speed is set to neutral the servo returns to it's start position and the bar blocks the bolt in the winch drum.

If we are still winching when the game is done, the spring tension pulls the bar back against the winch drum effectively doing the same thing.

Now for getting down.
We send the command (toggle switch) to the robot to winch down.
Motor actually winches up for 5 loops or about a 10th of a second rotating the winch drum bolt away from the bar ( .1 seconds is the time required by the servo to rotate from one extreme to the other). Servo pulls the bar out of the way and then we set the winch speed to unwind. It works extremely well.

Phil

[Steve Horton]

Originally Posted by Srkasner

Our team is using a globe motor to use the mast system on our robot to pull the robot off the ground after attaching to the bar. It has enough torque to pull up but it back drives awfully! Has anyone come up with a way to stop the globe motors from back driving? Thanx!

~Steve
Team 1124

Yep ! Sailboats use "stop blocks" or cleats which allow line to pass through one way, but not the other unless unlocked. Very simple.

[Phil_Lutz]

Originally Posted by Steve Horton

Yep ! Sailboats use "stop blocks" or cleats which allow line to pass through one way, but not the other unless unlocked. Very simple.

Cleats. What a great idea!

[EStokely]

<<Cleats. What a great idea!>>

We used one for our F-P powered lift. Th ecleat only failed when the rope was shreaded to the inner nylon by a faulty eyehook.

Very light weight too!