Setup and Calibration

We provide instructions for setting up and calibrating JoyLo. First, install the brs_ctrl package, our controller library for the Galaxea R1 robot and JoyLo, by following the instructions here.

Fixed Alias for JoyLo Arms

This step setups a fixed alias for JoyLo arms, as apposed to dynamic names. Plug in the u2d2, run the following command to get the U2D2 serial ID.

sudo udevadm info --name=/dev/ttyUSB0 --attribute-walk | grep ATTRS{serial} | head -n 1 | cut -d '"' -f2

Note, if the ttyUSB0 device already exists, look for other ttyUSB* devices that correspond to the U2D2.

Then, add the following to /etc/udev/rules.d/99-fixed-dxl-udev.rules. Replace <YOUR_U2D2_SERIAL_ID> with the serial ID you just found.

SUBSYSTEM=="tty", ATTRS{serial}=="<YOUR_U2D2_SERIAL_ID>", ENV{ID_MM_DEVICE_IGNORE}="1", ATTR{device/latency_timer}="1", SYMLINK+="tty_joylo"

To update and refresh the rules, run the following command:

sudo udevadm control --reload && sudo udevadm trigger

Now you should see a new device /dev/tty_joylo.

Low-Latency Mode

To achieve low latency between the JoyLo and the workstation, first set baudrate for all Dynamixel motors to 3000000 using Dynamixel Wizard. Then, set Return Delay Time to 0 for all motors using Dynamixel Wizard.

JoyCon Thumbsticks Calibration

This step calibrates the thumbsticks on the JoyCon controllers. It compensates for the neutral position drifting, and identifies the maximum and minimum position values of the thumbsticks.

To calibrate, start from the brs_ctrl root directory, and run the following command:

python3 scripts/calibration/calibrate_joycons.py

Then, follow the instructions in the terminal.

Calibrate JoyLo Joints Signs

Due to the installation variations, the signs of the joint angles may be flipped. The easiest way to calibrate the signs is through the simulation. Start from the brs_ctrl root directory, and run the following command:

python3 scripts/joylo/sim_joylo.py

Notice the left_arm_joint_signs and right_arm_joint_signs variables in the script. You need to flip the signs if the joints move in the opposite direction in the simulation.

joylo_arms = JoyLoArmPositionController(
    left_motor_ids=[0, 1, 2, 3, 4, 5, 6, 7],
    right_motor_ids=[8, 9, 10, 11, 12, 13, 14, 15],
    motors_port="/dev/tty_joylo",
    left_arm_joint_signs=[-1, -1, 1, 1, 1, 1],
    right_arm_joint_signs=[-1, -1, 1, 1, -1, 1],
    left_slave_motor_ids=[1, 3],
    left_master_motor_ids=[0, 2],
    right_slave_motor_ids=[9, 11],
    right_master_motor_ids=[8, 10],
    left_arm_joint_reset_positions=neutral_left_arm_qs,
    right_arm_joint_reset_positions=neutral_right_arm_qs,
    multithread_read_joints=True,
)

For more detailed usages of JoyLo, please refer to the brs_ctrl documentation.