Behind the Bumpers | 125 NUTRONs

https://youtu.be/fmK7OAET3F4 125 NUTRONs are back at it again with another well-designed, functional and ‘cute’ robot for the Charged Up game. Check out how well this robot is packaged with their awesome cube intake, multi-stage telescoping arm, gorgeous wrist and claw on Behind the Bumpers.

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Holy cow, how long is that arm?? Also, how much does the robot weigh?

The arm itself is 23” fully collapsed and has 52” of linear extension available beyond that.

The current weight is 78lbs, but we have a freshly powder coated steel belly pan to be added that adds 26lbs of ballast to the robot.

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Hi, How does the mechanism for the cable winch work?

Are you referring to the arm extension/retraction system?

No, I’m talking about the Winch used to spool the cables going out to the motors of the end effector.

The wires that go up to the manipulator go up the arm and then through 2 separate sliprings: a 4-wire slip ring for power to the 2 SparkMaxes in the End Effector and another 4 wire slip ring for the CAN connection.

The drum has a helix and is mechanically driven off the arm extension gearbox. It took some tweaking to get the ratio just right, but we did manage to get it just right. One of the other key aspects is you need to have some sort of tension mechanism in the system as a tolerance absorber and for direction changes. We just used surgical tubing on about a 8" section of cable to keep tension in the system.

Let me know if you have any other questions!
-Brando

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Can you link to the sparkmax slipring you used? I struggled to find a 4 wire slipring that could handle 40 amps on each wire

We ran our wrist and intake NEOs as 30A protected circuits.

Is a 30A protected circuit simply a 30A breaker in the PDH or is there more to it?

30A breaker, 30A current limits on the speed controller and then designing the mechanism at hand to work when ‘limited’ to 30A. Our wrist had to basically hold position constantly, but with the amount of reduction we had to make it easy to control, the 30A limit was not an issue.

The actual intake itself though required a fair amount of testing and prototyping to get the ideal balance of running it fast enough while also ensuring we could out-take a game piece. That was really the only compromise and meaningful additional work required for running them at 30A.

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To ensure efficient operation within the 30A current limit on the speed controller for your project📽, your team focused on designing a mechanism that could hold its position steadily while maintaining ease of control. While this constraint posed no issue for wrist stability, fine-tuning the intake mechanism was crucial. Extensive testing and prototyping were necessary to strike the right balance between speed:bullettrain_front: and the ability to efficiently handle game pieces. This effort proved to be the primary compromise and additional work needed to optimize performance while adhering to the 30A limit.

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