Add an immersive neck

Build, calibrate, and connect a two-axis camera neck for head-tracked teleoperation.

An immersive neck is an optional two-axis camera mount that follows the operator's head. Add it after the robot, headset, and at least one fixed camera work reliably.

Use Sentinel Runtime 0.13.0 or later.

Calibrate and test the neck without a camera installed. Incorrect motor IDs, limits, or direction settings can drive the mount into its stops and damage the motors or camera.

Choose a combination

Choose one camera and one motor system. All six combinations use the same Sentinel neck capability.

Camera	Feetech motors	Dynamixel motors	Compute requirement
Intel RealSense D435i	Supported	Supported	Any supported compute target
Stereolabs ZED Mini	Supported	Supported	`amd64-cu13` or `jp6.2`
Stereolabs ZED X Mini	Supported	Supported	Jetson Orin with a compatible GMSL2 capture card; use `jp6.2`

The camera changes the printed mounting bar and camera configuration. The motor system changes the controller board, motor setup software, calibration script, and neck adapter settings.

What you need

2 × Feetech STS3215-C018 servos
Compatible Feetech serial-servo controller
USB cable for the controller
Regulated 12 V motor power supply
Matching motor cables and printed neck parts
Feetech servo software

2 × ROBOTIS XC330-T288-T servos
ROBOTIS OpenRB-150 controller board
USB-C cable for the OpenRB-150
Regulated 12 V motor power supply
DYNAMIXEL TTL cables and matching printed neck parts
DYNAMIXEL Wizard 2.0

Browse the immersive neck hardware catalog and select the folder matching your motor and camera combination.

Build and configure the neck

Print the matching parts

Use the motor base and camera bar for your exact combination. Do not substitute a bar from another camera: weight, mounting holes, and cable routing differ.

Assemble the yaw motor at the bottom and the pitch motor at the top. Secure the base to a stable tripod or robot frame before applying power.

Configure the motor IDs

Both motor systems use:

Axis	Position	Motor ID
Yaw	Bottom motor	`2`
Pitch	Top motor	`1`

Use the Feetech software to configure one motor at a time. Set the bottom yaw motor to ID 2 and the top pitch motor to ID 1. Configure both for 1,000,000 baud before daisy-chaining them.

Install DYNAMIXEL Wizard 2.0 and confirm the OpenRB-150 has its USB-to-DYNAMIXEL firmware. Connect one unconfigured motor at a time so two factory-default ID 1 motors do not collide.

Set the pitch motor to ID 1, the yaw motor to ID 2, and both motors to 1,000,000 baud. Sentinel configures the operating mode it needs when the neck connects.

Connect data and motor power

Connect the controller board to the Sentinel computer over USB. Connect the servos to a regulated 12 V supply with the power disconnected, then verify polarity before switching it on.

ls -l /dev/serial/by-id/
ls -l /dev/ttyACM*

Prefer the stable /dev/serial/by-id/... path in the robot configuration. If your account cannot access the port, add it to the dialout group and sign out or reboot:

sudo usermod -aG dialout "$USER"

USB power alone is not sufficient for the motor bus. Do not connect or disconnect servo cables while motor power is on.

Calibrate both axes

Move each axis gently by hand when the script asks for its two safe extremes and neutral position.

python3 -m pip install feetech-servo-sdk
curl -O https://docs.avearobotics.com/scripts/calibrate.py
python3 calibrate.py \
  --port /dev/ttyACM0 \
  --yaw-id 2 \
  --pitch-id 1 \
  --output ~/sentinel/neck_calibration.json

python3 -m pip install dynamixel-sdk
curl -O https://docs.avearobotics.com/scripts/calibrate_dynamixel.py
python3 calibrate_dynamixel.py \
  --port /dev/ttyACM0 \
  --yaw-id 2 \
  --pitch-id 1 \
  --output ~/sentinel/neck_calibration.json

Recalibrate after changing a horn position, motor, printed part, camera bar, or mechanical stop.

Test motion without the camera

Keep the camera off the mount. Use the neck-only test configuration supplied with your setup to verify neutral, a small yaw movement, and a small pitch movement.

For the Feetech mount, you can also use the downloadable limit test:

curl -O https://docs.avearobotics.com/scripts/test_limits.py
python3 test_limits.py \
  --port /dev/ttyACM0 \
  --yaw-id 2 \
  --pitch-id 1 \
  --calibration-file ~/sentinel/neck_calibration.json

Keep one hand on the motor-power switch. Stop immediately if an axis moves opposite the requested direction, approaches a hard stop, or pulls a cable tight.

Install and verify the camera

Turn off motor power, install the matching camera bar, and route the camera cable with enough slack for full yaw and pitch travel.

Connect the D435i or ZED Mini over USB.
Connect the ZED X Mini to its GMSL2 capture card on the Jetson.
For ZED X Mini, verify zed_x_daemon and nvargus-daemon before starting Sentinel.

systemctl is-active zed_x_daemon.service
systemctl is-active nvargus-daemon.service

Both services are required only for the ZED X Mini path.

Configure Sentinel

Select the motor backend in the neck adapter. The camera configuration is independent, so the same motor block works with any of the three cameras.

neck:
  port: /dev/serial/by-id/<controller>
  baudrate: 1000000
  backend: feetech
  motor_model: sts3215
  yaw_id: 2
  pitch_id: 1
  calibration_file: /config/neck_calibration.json
  disable_torque_on_disconnect: true

neck:
  port: /dev/serial/by-id/<openrb-150>
  baudrate: 1000000
  backend: dynamixel
  motor_model: xc330-t288
  yaw_id: 2
  pitch_id: 1
  calibration_file: /config/neck_calibration.json
  disable_torque_on_disconnect: true

Point the daemon at the calibration file, then restart it and start the stack:

sudo systemctl edit sentineld
# In the override, set:
#   [Service]
#   ExecStart=
#   ExecStart=/usr/local/bin/sentineld --neck-calibration /absolute/path/to/neck_calibration.json
sudo systemctl restart sentineld
sentinel start

Contact the team at contact@avearobotics.com for the current camera and neck configuration matching your robot and hardware combination.

Verify the finished setup

Start disarmed

Confirm the neck serial port and camera open without errors before arming the neck.

Check camera output

Confirm the neck view appears at the configured resolution and frame rate without dropped-frame bursts.

Check direction

Make small head movements. Looking left must move the camera left; looking up must move it up. Correct reversed motion with invert_yaw or invert_pitch in the neck capability.

Check the full range

Move slowly through the usable range while watching motor clearance, the camera cable, and the physical stops.

Check disarm

Disarm the neck and confirm that the adapter disconnects and releases motor torque.

The neck is ready when the camera view is stable, small headset movements produce matching yaw and pitch motion, no cable tightens through the calibrated range, and disarming releases the motors.