baxter_interface is the Python library for programming Baxter through the bridge. It has the same classes and methods as the baxter_interface of Rethink’s original SDK, so old Baxter code ports easily. On top of that it has simpler additions, and it makes sure your program notices when the connection to the robot fails.
from baxter_interface import Limb, RobotEnable
RobotEnable().enable()
left = Limb('left')
print(left.joint_angles())
left.move_to_neutral()No ROS set-up code is needed: all classes share one ROS 2 node that runs in the background.
The classes
Every class has a guide in the repository’s docs folder.
| Class | What it does | Guide |
|---|---|---|
RobotEnable |
switches the motors on and off, resets after a stop | tools.md |
Limb |
an arm: joint angles, the hand to a place, paths through several points | arms.md |
Head, HeadLights |
turning and nodding; the halo and the sonar lights | head.md |
Gripper |
electric and suction grippers | grippers.md |
Camera, Display |
pictures from the cameras, pictures on the screen (as OpenCV images) | cameras-and-screen.md |
Navigator, DigitalIO, AnalogIO |
buttons, scroll wheels, lights | buttons-and-lights.md |
Sonar, RangeSensor, Accelerometer |
the sensors | sensors.md |
Robot |
one of several robots, by name | two-robots.md |
MobilityBase |
the base’s state, and driving it | mobility-base.md |
MotionPlanner |
motions planned by MoveIt, around obstacles | moveit.md |
What it adds to the original
- Simple moves.
left.move_by(z=0.10)lifts the hand 10 cm, andmove_to_pose()puts it at a place in metres.move_through()moves it through several points in one motion. - Several things at once. Commands inside an
at_once()block all start together, and the block waits until every one of them is done. That also works across both robots and the base. - A faster start. Parts created inside a
setup()block connect together, instead of one after the other. - Classes for the sensors, which the original SDK only offered as raw topics.
- Events. A function of your own can run whenever a button is pressed or the base’s mode changes:
navigator.button0_changed.connect(my_function). Each one runs in its own thread, and the library makes sure two of them don’t send commands to the same arm at once. - Honest connections. Creating a part waits until the robot has answered. A command that waits for the robot stops with an error as soon as the robot goes quiet, and the arm then holds its position. So a program never carries on as if a command had arrived when it hasn’t.
The command-line tools
| Tool | What it does |
|---|---|
enable_robot |
shows the robot’s state, switches the motors on and off, resets after a stop |
robot_info |
the robot’s software version and other facts |
move_to_neutral, tuck_arms |
the arms to a safe pose, or folded up for transport |
camera_control, show_image |
the cameras, and a picture on the screen |
joint_trajectory_action_server |
lets other ROS 2 software, such as MoveIt, move the arms along paths |
smoke_test |
Rethink’s self-test of the robot’s main functions |
tare, calibrate_arm |
the robot’s own maintenance routines for the arms |
base_status |
the Mobility Base’s mode, battery, bumpers and speed |
Run them with ros2 run baxter_interface <tool>, in a terminal set up with source ~/baxter_ws/baxter.sh, or with docker compose run --rm client in front on a computer without ROS 2. smoke_test, tare and calibrate_arm ask before they start. move_to_neutral and tuck_arms move the arms straight away.
Examples
The repository has 17 short example programs: reading the robot, moving an arm and a hand, the head, the screen, buttons, cameras, grippers, sensors, waving, teach-and-repeat, the trajectory action, at_once(), the head lights, two robots, the Mobility Base and MoveIt.
Seeing and planning
- RViz shows the robot in 3D, live from the real robot. See rviz.md.
- MoveIt 2 plans motions that avoid the robot’s own body and obstacles you describe, from RViz or with
MotionPlanner. It uses the values of Rethink’s original MoveIt configuration. On the real robot it so far runs cleanly only at a tenth of full speed.