Day 47 – Comp Bot Assembly 2: SMH Vex (02/19/2020)

Authors: Andrew Georgioff,  Ritik Mishra

Applying Loctite to Falcons

We fixed a minor issue with our competition robot drivetrain Falcons. There is a small performance issue with Falcons where the internal screws that hold the shaft to the motor come loose, turn into screw dust, and permanently destroy the motor and lock the shaft from spinning.  Other teams on Chief Delphi have confirmed that this is a problem. Although this is only a minor problem that Vex could have plausibly overseen during Falcon testing, we strive for perfection on our team. To prevent this from happening to us, we secured the screws using Loctite. This took a while since it is a process to disassemble and reassemble a Falcon, even though some of the screws came in the mail pre-loosened. One concern that we have is that the loctite will come loose if the motors heat up too much, but at least they will stay good for a while longer.

Code Testing

We experimented with changing several motor speeds in code today to optimize mechanical performance. Some tests included

  • Running the bottom roller at 50% vs 100% speed without the top roller installed
    • 100% speed would throw the ball on top of the electronics, 50% worked pretty fine
    • The lack of a top roller meant that balls would occasionally get stuck between the third intake roller and the bottom squeezer roller
  • Running the hopper asymmetrically in the same direction (75% & 25%) vs opposite direction (75% & -25%)
    • We found that running one side of the hopper backwards prevented balls from easily getting out from between the the third intake roller and bottom squeeze roller. 

We also fixed the problem in the autonomous where the robot wouldn’t drive off of the initiation line. This problem was caused by the fact that the autonomous command was not cancelling out the teleop command, which was telling the robot to not do anything since the joysticks are untouched in autonomous.

Gearbox Covers

They exist for the comp bot now 🙂

Above: A picture of a spraypainted comp bot gearbox cover installed on the gearbox

Comp Bot Assembly

We did a few things today

  • One of the two airpods is on the robot. We are waiting to put the other one on until we get all the belts and rollers and everything else that would otherwise require disassembly of the airpods.
  • The shooter motors now have belt pulleys installed, and the spacer/wheel stack on the shooter axle is mostly complete
  • The hopper is ready to get installed onto the robot after we get the hopper plates manufactured and drivetrain completed (it is a large pain to install drive axles/gearboxes with the hopper in the way).

One of these days, we will need to remove the black shooter hood from the practice bot to put onto the comp bot

Quote of the Day: What is this size? It’s larger than everything and smaller than everything – Isaac AJ, senior engineering captain looking for an Allen wrench while fixing Falcons