Build & Calibration Guide

1. Build Overview

This guide walks you through building the platform with 2× SO-101 follower arms, a neck/head assembly, an omni-wheel base on an IKEA RÅSKOG cart, and an NVIDIA Jetson compute node mounted near the neck/base region.

The 3-Bus Separation

We use three independent motor buses to simplify wiring and isolate faults during motor debugging.

Recommended Build Order

1. Print all parts
2. Assemble both SO-101 arms
3. Install wrist camera mounts and grippers
4. Assemble cart and wheel base
5. Assemble neck / top base / head
6. Configure motors (before final assembly)
7. Mount Jetson and route wiring
8. Final mechanical assembly and cable management
9. Software bring-up and bus verification

2. 3D-Printed Parts

About 90% of the structural components are 3D-printed. Download the combined 3MF and apply the Pro print settings below.

On the GitHub page that opens, click the “Raw file” button (top-right of the file viewer) to download the .3mf.

You will need: two SO-101 follower arms, the neck/head assembly, the omni-wheel base, and a wrist-camera mount per arm. Print the soft finray gripper fingers in TPU95A.

3. Print Settings

Start from your baseline PrusaSlicer profile (or a standard PLA profile), then change only the settings below. Parts were validated on a consumer printer (e.g. Bambu A1) in PLA; PETG and CF variants are optional strength upgrades.

General Print Notes

• Use PLA for first-pass prototyping and fit checks
• Prioritize part orientation for structural parts over cosmetic finish
• Dry filament in high humidity for cleaner fit-up and thread quality
• For soft finray-style fingers, use TPU95A

4. Assembly

Overall Assembly

Watch the overall assembly guide for a complete walkthrough of the build process.

A) Cart

Assemble the IKEA RÅSKOG cart first to establish the rolling structure.

• Do not finalize cable routing through the cart yet
• Leave access for motor extensions, USB data, power, and camera cable routes

B) Arms (Joints 1–5)

Assemble both SO-101 follower arms (step-by-step build video). Crucial wrist/gripper order:

1. Before attaching the gripper to joint 5, install the wrist-camera attachment to the gripper
2. Install the gripper claw/fingers
3. Use the follower gripper approach on both arms

This order avoids reopening the wrist stack later.

C) Neck (Top Base & Head)

Assemble the Top Base and Head. The head follows the same motor style and is derived from early SO-101 link patterns. The hollow neck doubles as a cable channel.

Watch the neck assembly (overall assembly video, 0:00–18:51).

D) Wheels & Wheel Base

Assemble the wheels and wheel base.

Watch the wheel assembly (overall assembly video, 18:52–32:30).

• Keep omni-wheel orientation/order exactly as documented
• Use motor cable extensions — do not rely on short direct runs
• Leave slack until top-plate routing is finalized
• Mount the top plate and connectors only after route checks

E) Integrating Components onto the Cart

Bring the arms, neck, and wheel base together on the cart for the full platform.

Watch the full integration onto the cart (overall assembly video, 32:35–39:52).

5. Motor Configuration & IDs

Configure motors before final cable management and hard mounting. Many servos ship with default ID 1, so each ID must be unique per bus and the baudrate must match the board and motors.

A) Arm Motors (SO-101)

Identify each serial port, then configure the motors one at a time — set each ID and the baudrate, and repeat for both follower arms.

B) Neck & Wheel Motors (Bus 3)

Assign each ID one at a time with the repo's set_motor_id.py tool. On Linux you may need serial permissions (sudo chmod 666 /dev/ttyACM0).

ID Planning

6. NVIDIA Jetson Placement

Mount the Jetson at the base of the neck or in the center storage shell area, depending on your printed configuration.

• Keep mass low for stability
• Keep USB ports accessible
• Minimize cable length to the three motor control boards, two wrist cameras, one head camera, and power distribution

7. Wiring (3-Bus)

Wire the three buses as below.

A) Motor Wiring

• Bus 1 — Left arm: one dedicated controller; daisy-chain follower motors; controller output to joint 1 (shoulder pan)
• Bus 2 — Right arm: one dedicated controller; same layout as left arm
• Bus 3 — Neck & wheels: one dedicated controller; use extensions for clean routing from the lower wheel plate to the upper electronics

Leave service slack near each joint (especially wrist/gripper), avoid tight bends near connectors, keep motion cables away from pinch points, and label both ends of every extension.

B) Power Wiring

• Battery mounted low and upright in the cart
• Main power line routed to a distribution point
• Separate fused outputs for left-arm bus, right-arm bus, neck/wheel bus, and the Jetson power path
• Add strain relief at the battery and distribution points

C) Camera Wiring

• Wrist cameras (×2): route each cable along its arm with full-motion slack; secure at intervals; keep compute-end connectors accessible
• Head camera: route through the hollow neck; leave pan/tilt slack at the head joint

8. Final Assembly

Complete final assembly, substituting the Jetson where older instructions reference a Raspberry Pi.

• Complete wiring and cable management before clamping the top base into the cart
• Clamp arms onto the cart corners after route verification

Final Checklist

9. Hardware Calibration & Validation

Run these checks before full-stack teleoperation or training. Test one bus at a time.

A) Bus & Joint Control Sanity Check

Ping/read all motors per bus, then confirm joints respond to keyboard input.

B) Mechanical IK Calibration

Verify the gripper reaches the expected location. Check for loose servo horns or bent brackets if accuracy is low — accuracy depends on mechanical assembly quality.

C) Motion & Camera Bring-up

• Arm joints move correctly; neck axes move correctly; wheels respond with expected direction
• Wrist camera 1, wrist camera 2, and head camera streams verified