Many robots will be using the worm gear drives to control arms and claws. Since these cannot be back driven manually how do we put the robot back into a transportable configuration after a match? In the shop we connect the arm motors to a portable battery and run it back to position manually. Would this be legal under the safety rule <R17> that say the robot cannot be powered up after a match?
Team 2272
We had a Similar Issue with our 2007 Robot, and we did one of two things. We either carried our robot off the field in it’s open configuration (ramps down) and waited until we were off the field to tether it up or right as the match came to a close we would close the robot up. Depending on your design an how your matches go, either of these could work for you.
If you really wanted to use an auxiliary battery and are concerned with R17 then I would suggest consulting the Q&A for a definitive answer.
I think the most appropriate thing to do would be to add a mechanical crank attachment point. Bring the motor shaft, or some other back-driveable point, out to a spot you can connect to when the robot is powered down. For bonus points, make it able to be driven by a portable drill or battery-powered screwdriver.
Using a standalone battery to power that motor down is a good way to do it… but you won’t have time for it on the field. In fact, we used a boat winch to pull our robot up to the bar last year, and used a separate battery to reset back in our pits after each match. Of course, we were able to safely remove the robot from the field without needing to do this.
So, I would think you need a different way to lower your arm to safely remove the robot from the field - perhaps some sort of clutch that could disengage the arm from the motor/worm gear, allowing you to lower it (and then re-engage the clutch before your next match)?
Any idea on how to access the worm gear on the denso motors to insert a crank?
I don’t believe it’s possible within the rules because of the integral gearbox. I would insert a way to decouple the motor from the output if you need to backdrive or reset on the field without control.
We have a similar issue - if we use the denso motor to grip the game pieces tightly, how do we release the game pieces at the end of the match? There is no way they will let us walk off the field with a tube.
As I read <R17>, it says we cannot activate the robot power system. A 9V battery across the denso isn’t enought to move the motor, but it is enough to let you manually backdrive it.
Does anyone know if attaching a 9V battery to the robot after the match would be allowed?
It’s illegal. There are numerous rules that would come into play, but here are the two that stick out most.
<R17> Field power to the ROBOTS will not be re-enabled after a MATCH. ROBOTS must be
designed to permit removal of GAME PIECES from the ROBOT, and removal of the ROBOT
from other FIELD elements and/or other ROBOTS without requiring activation of the ROBOT
power system.
This rule has been in every manual that I can remember. When designing your robot you must keep this in mind. If you cannot remove game pieces from your robot in an un-powered state then you are in violation of this rule.
<R48> All electrical loads (motors, actuators, compressors) must be supplied by an approved power
regulating device (speed controller, relay module, or Digital Sidecar PWM port) that is
controlled by the cRIO-FRC on the ROBOT.
R48 would make your 9V battery illegal.