16-299: Elegoo Tumbller balancing robot assembly.

Atkeson's Elegoo Tumbller balancing robot assembly.

This information is intended to augment the assembly tutorial/manual that comes with the robot.
WTF!

Unboxing.

The battery, old controller board, MPU6050 IMU, and ultrasound device have been removed from the box. Get a charged battery and new controller board from the TA. The battery has been charged, but you should charge the battery again just to make sure it is charged.
Keep the parts in the little plastic bags until you need that part. Especially the screws. Only take what you need for the current step from the bags, or you will have a hard time figuring out which screw is which.

Get your battery charging first thing.

A USB cable is included.

The charging port.

I don't know if the switch should be on or off while charging. I put it to off.

The light is on or flashing (green) while charging, and goes off when fully charged. A red light means the battery needs to be charged.

Mount the motors.

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It doesn't seem to matter which side of the blue plate is up.

Only use 4 screws (top and bottom) for each motor.

Put the hubs on.

There are reports on the web of these hubs coming loose, and when the control system starts to oscillate this is where it happens, so adding (blue) loctite or the equivalent to the lock screws and even the axle may be a good idea in this part of the assembly.
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The shaft has a flat. Align one screw to the flat, and screw that screw in first, so the coupling aligns with the flat.

Put the tires on.

The screws are also M4x6 from bag 3.

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Put the stand on.

Install the motor wires

In this photo the connector is partially inserted. Note that the ridges on the connector on the wires matches the indentation on the motor connector, and these ridges should be visible to you.

In this photo the connector is fully inserted.

Note that the motor wires are threaded through the nearest slot in the blue metal base plate.

Get a new controller board from the TA

The processor and red power electronics board are already installed.

Mount the controller board.

Screw four short brass standoffs to the blue metal base plate (make sure the holes you use match the holes in the controller board).

Move the wires out of the way.

Note that the rows of pins on the controller board face the back of the robot.

Connect the motors to the controller board.

The connectors are "keyed" the same way as the motor connectors, with the ridges on the motor cable connector visible. I try to push the extra wire under the controller board to keep it out of the way. The screwdriver is useful for this.

Here the extra wires are nicely tucked under the controller board.

Mount the standoffs for the top plates

This photo has an older version of the controller board. I forgot to photograph the same picture with the new controller board. Whoops.

Mount the battery on its plate.

Mount the battery plate on the robot.

The battery goes on top of the plate, with the wire on the side with the battery connector (see next photo). Make sure the battery is turned off.

Here the battery plug is partially inserted in the POWER_IN connector on the controller board. Note the ridges on the connector which indicate how it should be inserted (also note the colors of the wires, which are another clue). Fully insert the cable into the connector. Note the artistic wrapping of the battery cable around the standoff, to avoid loose wires flapping around when the robot moves.

Lock down the battery plate by screwing in the mid-size standoffs. You can now get some gratification by turning the battery on and seeing the processor and battery lights come on. That is enough gratification for now. Turn the battery off.

Mount the top plate.

Test the USB cable.

Plug a USB cable into your laptop and the processor board. The processor should light up, as well as the battery lights. Very gratifying.

The Arduino USB connectors are fragile, and can easily be broken off the board. Please be gentle inserting and removing the USB cable. If you want to be really safe, never unplug the USB cable at the Arduino and use a second USB cable to charge the battery.

Now plug a USB cable into the battery and make sure the charging light turns on. Also very gratifying.

Strain relief the USB cable.

Unplug the USB cable and wrap the USB cable around a standoff and secure it with a wire tie. The USB connector on the processor board can easily be ripped off, which is a fatal injury, so let's avoid that. The USB cable needs to be able to reach both the processor board and the battery connectors.

Training wheels

I add "training poles" when I am debugging a new balancing controller. The training poles are chopsticks from a local Chinese restaurant (or the NSH Atrium).

I attach wire ties LOOSELY and then thread a chopstick on the INSIDE of the motor support.

Ignore the hair on the wheel axle, this is actually a "used" robot in the photo.

Then tighten and cut off the wire ties. I position the chopsticks so that the plastic stand piece is just off the ground, since that plastic piece often comes loose or breaks.

Check your work.

Extra parts.

Put them in a bag and give them to the TA.
WTF!