Do the Dynamixel Servos Need to Be Centered Before Assembly, and What Is the Robot’s Neutral Pose?

[quickdokong]

Hi,

I am currently assembling the Microban robot and have a question about the initial positions of the Dynamixel XL330-M288-T servos.

The Assembly Guide explains how to configure each servo’s ID, baud rate, Return Delay Time, PWM Slope, and Shutdown value. However, I could not find any instructions about setting the servos to specific positions before attaching the horns and assembling the joints.

Do the servos need to be moved to their center position—for example, position 2048—before mechanical assembly?

Alternatively, can they be installed in any position, with the software handling the joint offsets and neutral pose automatically?

I am particularly concerned about the first time I run make run, because the Usage Guide says that torque will be enabled and the robot will ramp to its neutral pose.

Could you please clarify:

1. Is there a required initial position for each servo before assembly?
2. Should the Homing Offset remain at its factory default?
3. Should all joints be assembled with the servos at position 2048, or do different joints require different installation positions?
4. What exactly does the robot’s “neutral pose” look like? Is there a picture, diagram, or list of target joint angles for reference?
5. Is there a recommended procedure for safely checking the servo positions and mechanical assembly before the first make run?

Thank you!

[MarcDcls]

Hi! Glad to see a new Microban is being built! Good questions.

Initial position & joint assembly
Yes, the motors must be set to 0 (which is position 2048 in the Dynamixel Wizard) before assembly. However, if you have already set up the IDs and baud rates, you don't need to plug them back into the Wizard just for this. You can simply look at the servo horn: there is a single notch that points directly up (towards the LED) when the motor is at 0. Be careful not to confuse it with the double notch on the opposite side.

To guide you during the mechanical assembly, you can refer to the Onshape assembly where all the motors are shown exactly at their 0 position.

Homing Offset
The Homing Offset must remain at its factory default value (0).

The Neutral Pose
The neutral pose is the standard standing posture. It corresponds roughly to 0 on all DOFs, with a few small 5 to 10° offsets for aesthetic reasons. The exact configuration is defined as NEUTRAL_POSE in src/constants.py. This is also the posture you will see if you launch the simulation or the viewer (make sim or make viewer).

Safely checking positions before the first run
If you want to safely check the motor positions before executing make run, you can SSH into the robot and run rustypot_wizard. It is already included in the provided robot image and acts as an onboard equivalent to the Dynamixel Wizard, so you can move the motors one by one. If needed, you can find its repository here: rustypot_wizard.

Hope this helps for the final assembly steps 😉