AlohaMini2 Assembly Guide

AlohaMini2 is the reinforced successor to AlohaMini1. It uses AM-ARM200 arms instead of SO-ARM100/101, upgrades the lift servo from STS-3215 to high-torque STS-3095, and strengthens the chassis for higher base loads. All printed parts are designed to fit a standard Bambu P2S printer.

This guide covers the AlohaMini2 Mobile Base 2 assembly. Prepare the follower and leader arms in advance using the AM-ARM200 Assembly Guide.

Servo ID Setup

Assign servo IDs before installing the servos. Configure one servo at a time to avoid ID conflicts.

Servo	ID	Location
Rear-left wheel	10	Chassis
Front wheel	9	Chassis
Rear-right wheel	8	Chassis
Lift axis	11	Shoulder block

Using lerobot_alohamini

The recommended command is provided by the lerobot_alohamini repository. Clone that repository, install its dependencies, and run the command from the repository root:

git clone https://github.com/liyiteng/lerobot_alohamini.git
cd lerobot_alohamini

Example:

python examples/debug/motors.py configure_motor_id \
  --id 1 \
  --set_id 8 \
  --port /dev/ttyACM0

You can also use the Feetech FD Debug Tool through the Waveshare bus servo controller. Use baud rate 1000000, scan the connected servo, write the target ID, then disconnect it before configuring the next servo.

1. Build the Chassis

Remove all print supports from the chassis parts, especially the wheel pockets, cable channels, and dowel-pin slots.

Apply epoxy to the mating surfaces.

Insert OB_Chassis_Locking_Wedge.stl into the locking-pin slot. The three chassis locking pins are tapered; install them in the correct direction so they can wedge the tower base tightly after assembly.

Apply epoxy to the OB_Chassis_Frame_Joiner.stl joiner, then press the chassis parts together until they are fully seated.

Install the three wheel servos in the chassis.

After assigning servo IDs, place the servos in the chassis in the orientation shown below.

Connect servo 8 to servo 9, servo 9 to servo 10, and servo 10 to servo 11. Because servos 10 and 11 are far apart, use at least a 90 cm 3-pin servo cable; a 140 cm cable is recommended. Fasten the servos with the screws supplied with the servos.

2. Install the Omni Wheels

Pre-install four M3x10 screws into each wheel-to-servo connector. Press the connector onto the servo output disc, confirm that all four mounting holes are aligned, then tighten the screws through the access opening.

Install each omni wheel with its axle, 12x18x4 mm bearings, washers, and bearing cover.

The chassis assembly is now complete. At this point, you can use the debug command in the lerobot_alohamini repository to drive the base directly for a first test.

python examples/debug/wheels.py --port /dev/ttyACM0  # W/S/A/D drive test

3. Build and Mount the Lift Tower

Build the tower in this order:

O_POST4_Connector_Base.stl -> O_Main_Assembly_Post4.stl -> OB_Main_Assembly_Post3.stl -> OB_Main_Assembly_Post2.stl -> OB_Main_Assembly_Post1.stl

Apply epoxy to each contact surface, stack the parts in order, and wipe away excess adhesive before it cures.

Place the chassis with servo 9 facing you. The lift rack should also face you. Press the tower's hex base into the chassis socket, flip the assembly over, and tap evenly around the six side faces until the flange sits fully flush with the chassis.

Route the wheel servo cable through the center hole and side cable channels, then return the base upright.

4. Build the Shoulder Lift Block

Press the eight 4x13x5 mm track bearings into the shoulder bearing block. All bearings should sit flush and rotate freely.

Pre-install four M3x10 screws into the lift gear, then insert the 12x25 mm shaft from the right side. Rotate the gear until the screw tips drop into the servo output disc holes, then tighten the screws through the side access windows.

Bond the shoulder T-frame with epoxy and let it fully cure before loading the arms.

Slide the shoulder T-frame onto the tower rails. It should travel smoothly without binding.

5. Install the Cameras

Install the two top cameras into the printed top camera mounts. Remove each camera back cover, place the printed mount/back-cover part between the camera body and cover, and fasten it with two M2x12 screws.

Install the chest camera in the front bracket using the same back-cover mounting method.

6. Mount the Follower Arms and Route Cables

Fasten the left and right follower arms to the shoulder T-frame using the long M3 socket screws and M3 nuts. One arm mounts on each side.

Feed the arm and camera cables through the cable ports in the lift tower.

Connect the 3-pin cable from lift servo 11 to the servo driver board on the left arm. Leave enough slack for the shoulder to move through its full vertical travel.

Side	Cable bundle
Left	Arm power, arm Type-C, wrist camera USB, chest camera USB, lift servo cable
Right	Arm power, arm Type-C, wrist camera USB

Slide protective cable sleeves over the routed bundles.

7. Install Display, Compute, and Power

Fasten the display to its printed bracket with four M3x6 screws, slide the bracket into the rear dovetail slot, and connect the short micro-HDMI cable plus Type-C power cable.

Mount the Raspberry Pi 5, buck converter, battery packs, and counterweight in the rear support.

Wire power as follows:

Power path	Connection
Arm power	Battery 1 -> 2-to-1 splitter -> left and right arm DC cables
Compute power	Battery 2 -> buck converter -> Raspberry Pi Type-C power port

8. Functional Test

Before running the full robot, test each moving subsystem:

python examples/debug/wheels.py --port /dev/ttyACM0  # W/S/A/D drive test
python examples/debug/axis.py --port /dev/ttyACM0    # U/J lift test