Mount and Wire Two Arms

The full step-by-step hardware setup guide with photos and torque specifications is at hardware/dk1/setup. This unit walks you through the key decisions and checks that matter most for bimanual operation — read this alongside that guide.

Workspace Geometry

Bimanual workspace setup is the most consequential physical decision you will make. Get it wrong and you'll fight joint limits throughout the entire path. Get it right and teleoperation will feel natural from the first session.

Key constraints for the DK1:

• Arm separation: Mount the two follower arms 45–55cm apart (center-to-center of base plates). Closer limits reach without inter-arm collision avoidance. Further apart limits the workspace overlap needed for handoff tasks.
• Symmetrical mounting: Both bases should be at the same height and depth from the table edge. Use a straight edge to verify alignment — even 1cm of offset introduces a systematic bias in your training data.
• Table rigidity: A rigid steel or hardwood table is required. Both arms exert significant torque during operation. A folding or plastic table will flex and introduce inconsistency between demonstrations that is impossible to train out.
• Leader arm position: Mount the leader arm at a comfortable operating height in front of you, with clear sightlines to the follower workspace. You should be able to see both follower arms and the task surface without turning your head.

Hardware Setup Steps

1. Mount the follower arms

   Bolt both follower arm base plates to the table using the M6 hardware included in the kit. Torque to 8 N·m — snug but not stripped. Verify neither base plate rocks. Measure arm separation and adjust if needed before tightening fully.

2. Mount the leader controller arm

   The leader arm uses a clamp mount and does not need to be bolted down — it should move freely. Position it so you can comfortably reach all joint limits with both hands. The leader arm is your teleoperation interface for the rest of this path, so ergonomics matter.

3. Connect power to both follower arms

   Plug in both power supplies and confirm the status LEDs on each arm's base show solid amber (standby, unpowered servos). Do not connect USB yet. Verify power supply labels match your wall voltage before plugging in.

4. Connect USB from each arm to your computer

   Connect all three USB-C cables: follower arm A, follower arm B, and the leader arm. Confirm your OS detects three serial devices. Run ls /dev/ttyUSB* — you should see ttyUSB0, ttyUSB1, and ttyUSB2. Note which physical arm maps to which device path — you will need this in Unit 2.

5. Position cameras for bimanual workspace coverage

   Camera placement for bimanual is more demanding than single-arm. You need: (1) a wide-angle workspace camera with both arms and the full task surface visible — mount this 60–80cm above the table, pointing straight down or slightly angled; (2) a wrist camera on the primary follower arm's end-effector mount. Verify both cameras appear as /dev/video* devices. Cable management matters — route cables so they cannot enter the follower arm workspace.

6. Mark the workspace boundary with tape

   Before powering on servos, manually move each follower arm through its full range and mark the outer boundary of the reachable workspace with tape on the table. The intersection of both arms' workspaces — where both can reach simultaneously — is your bimanual task zone. Mark this inner overlap zone clearly. All task objects will be placed here.

7. Power-on and joint state check via web UI

   Open a browser to http://localhost:8080/dk1 after starting the DK1 hardware server (covered in Unit 2's SDK install). For now, verify both arms respond to the "enable servos" command in the web UI and that joint state readings update in real time. Both arms should report idle joint states with no error flags.

Calibration Reference

The leader arm is the calibration reference for the entire system. After mounting, verify that the leader arm's zero position — all joints at 0° — maps cleanly to a neutral, centered posture on both follower arms. This calibration check happens in Unit 2 once the SDK is installed. For now, ensure the leader arm can be manually moved to a neutral pose without binding.