ROS 2 API

CORA uses ROS 2 as the distributed robotic software backend. Usage is largely the same as any other ROS 2 application. The supported release is ROS 2 Jazzy LTS on Ubuntu 24.04.

Packages

The ROS 2 backend spans three repositories, each a self-contained workspace:

Repository	Contents
cora_common	Shared packages used by both real robot and simulation
cora_robot	On-board robot packages: ODrive ros2_control hardware interface, ODrive setup scripts
cora_desktop	Desktop simulation packages: Gazebo launch files and world configs

cora_common packages

Package	Purpose
`cora_bringup`	Top-level launch files for real robot and simulation
`cora_codi`	ROS 2 bridge node connecting the CoDI SDK to the hardware stack
`cora_description`	URDF, XACRO, and mesh files for the robot
`cora_gripper_1_description`	URDF and meshes for the default gripper
`cora_moveit`	MoveIt 2 Python action server (`mover_node`) and keyboard servo test
`cora_moveit_config`	MoveIt 2 SRDF, kinematics, and controller config
`cora_msgs`	Custom message and action definitions
`cora_vision`	Lifecycle camera node and ArUco marker detection

cora_robot packages

Package	Purpose
`odrive_ros2_control`	ros2_control hardware interface plugin for ODrive v3.6 over CAN
`odrive_msgs`	ODrive-specific ROS 2 messages (axis state, errors, joint status)
`odrive_base`	SocketCAN and CAN message helpers (C++ headers)
`odrive_setup`	Python scripts for ODrive configuration and calibration

ROS 2 Interfaces

Topics

Topic	Type	Publisher	Notes
`/joint_states`	`sensor_msgs/JointState`	`ros2_control_node`	Joint positions
`/tf`	`tf2_msgs/TFMessage`	`robot_state_publisher`	Full transform tree
`/tfstatic`	`tf2_msgs/TFMessage`	`static_transform_publisher`	`world` → `base_link`
`/robot_description`	`std_msgs/String`	`robot_state_publisher`	URDF string latched on startup
`/servo_node/delta_twist_cmds`	`geometry_msgs/TwistStamped`	`codi_node`	Real-time Cartesian velocity commands
`/servo_node/delta_joint_cmds`	`control_msgs/JointJog`	`codi_node`	Real-time joint velocity commands
`/servo_node/delta_pose_cmds`	`geometry_msgs/PoseStamped`	`codi_node`	Real-time Cartesian pose commands
`/arm_controller/joint_trajectory`	`trajectory_msgs/JointTrajectory`	`servo_node`	Outgoing trajectory to arm controller
`/gripper_cam/image_raw`	`sensor_msgs/Image`	`camera_node`	Raw gripper camera feed
`/gripper_cam/aruco`	`vision_msgs/MarkerArray`	`vision_node`	Detected ArUco markers

Actions

`posegoal` — `cora_msgs/action/PoseGoal`

The main motion planning action. Served by mover_node in cora_moveit, called by codi_node.

Goal

cora_msgs/TargetedPoseStamped pose_goal   # Cartesian pose + target frame
float64[] joint_goal                      # Joint positions [J1..J6] in radians
float64 gripper_goal                      # Gripper opening in metres
string predefined_pose                    # Named state from SRDF e.g. 'standby', 'straight'
string space                              # 'TS' (task space) or 'JS' (joint space)
string interface_type                     # 'position', 'velocity', 'acceleration', or 'effort'

Result

geometry_msgs/PoseStamped pose_result     # Achieved end-effector pose
float64[] joint_result                    # Achieved joint positions
string status_result                      # 'Complete' or error description
bool success

Feedback

geometry_msgs/PoseStamped pose_feedback
string status

`arm_controller/follow_joint_trajectory` — `control_msgs/action/FollowJointTrajectory`

Standard ros2_control trajectory execution action for the arm group (J1–J6). Used internally by MoveIt 2.

`gripper_fingers_controller/gripper_cmd` — `control_msgs/action/GripperCommand`

Standard parallel gripper action for the gripper_fingers group (Finger1, Finger2).

Services

MoveIt Servo

Service	Type	Notes
`servo_node/switch_command_type`	`moveit_msgs/srv/ServoCommandType`	Switch between `JOINT_JOG`, `TWIST`, and `POSE` input modes

Lifecycle nodes

Service	Type	Notes
`/vision_node/change_state`	`lifecycle_msgs/srv/ChangeState`	Activate/deactivate ArUco detection
`/camera_node/change_state`	`lifecycle_msgs/srv/ChangeState`	Activate/deactivate camera node
`/controller_node/change_state`	`lifecycle_msgs/srv/ChangeState`	Activate/deactivate controller node

MoveIt 2 (via `move_group`)

Service	Type
`/compute_ik`	`moveit_msgs/srv/GetPositionIK`
`/compute_fk`	`moveit_msgs/srv/GetPositionFK`
`/plan_kinematic_path`	`moveit_msgs/srv/GetMotionPlan`

Custom message definitions

`cora_msgs/msg/TargetedPoseStamped`

string target_frame                       # 'Gripper', 'Camera', or 'endeffector'
geometry_msgs/PoseStamped pose

SRDF — planning groups and named states

Group	Joints
`arm`	J1, J2, J3, J4, J5, J6 (chain: `baselink` → `endeffector`)
`gripper_fingers`	Finger1, Finger2

Named state	Group	Description
`straight`	arm	All joints at 0 rad
`standby`	arm	Folded upright position
`standby_2`	arm	Alternate standby
`open`	gripper_fingers	Finger1 = 0.035 m
`closed`	gripper_fingers	Finger1 = 0 m

Launch files

`bringup.launch.py`

Full robot launch. Starts the CoDI node after a 30 s delay to allow MoveIt to initialise.

ros2 launch cora_bringup bringup.launch.py \
  hardware_type:=Real \
  gripper_package:=cora_gripper_1_description \
  use_codi:=true

Parameter	Options	Default
`hardware_type`	`Fake`, `Real`, `Gazebo`	`Fake`
`gripper_package`	any gripper description package	`None`
`use_codi`	`true`, `false`	`true`
`launch_rsp`	`true`, `false`	`true`

`move.launch.py`

Full MoveIt 2 stack: move_group, servo_node, ros2_control_node, robot_state_publisher, RViz, and controller spawners.

ros2 launch cora_moveit move.launch.py \
  hardware_type:=Real \
  use_servo:=true \
  use_moveitpy:=true \
  gripper_package:=cora_gripper_1_description

`vision.launch.py`

Camera node and ArUco detection.

ros2 launch cora_bringup vision.launch.py

`gazebo.launch.py`

Full Gazebo simulation with bridge, spawner, and bringup.

ros2 launch cora_gazebo gazebo.launch.py \
  gripper_package:=cora_gripper_1_description

Simulation

Installation

git clone --recurse-submodules https://github.com/C-O-R-A/cora_desktop.git
cd cora_desktop
bash install.sh
source install/setup.bash

Usage

ros2 launch cora_gazebo gazebo.launch.py

MoveIt 2 and RViz launch alongside Gazebo. Use the MoveIt motion planning panel in RViz to plan and execute trajectories, or send PoseGoal action goals via CoDI.

Real Robot

ODrive Setup

Each joint uses an ODrive v3.6 board over CAN at 250 kbps. Node IDs are assigned per-joint in cora.ros2_control.xacro (J1=0, J2=1, ... J6=5, Finger1=6).

1. Bring up CAN interface

sudo ip link set can0 up type can bitrate 250000

This is automated on boot via the can0-up.service installed by install.sh.

2. Load motor config

# 6354 270KV motors
odrivetool restore-config odrive_setup/configs/closed_loop_6354.json

# 5065 140KV motors
odrivetool restore-config odrive_setup/configs/closed_loop_5065.json

3. Calibrate

python3 odrive_setup/quicksetup.py odrive_setup/configs/closed_loop_6354.json --axis 0

This automates the full calibration sequence: config restore → full calibration → set pre_calibrated flags → save and reboot.

4. Test

python3 odrive_setup/quicktest.py --axis 0 --mode velocity

Installation

git clone --recurse-submodules https://github.com/C-O-R-A/cora_robot.git
cd cora_robot
bash install.sh
source install/setup.bash

Usage

ros2 launch cora_bringup bringup.launch.py \
  hardware_type:=Real \
  gripper_package:=cora_gripper_1_description

:::warning CAN bus Make sure can0 is up before launching. The install.sh installs a can0-up.service systemd service that brings it up automatically on boot. :::

Adding a Custom Gripper

Create a package with this structure:

gripper_description/
    meshes/
    urdf/
        cora_gripper.urdf
        cora_gripper.urdf.xacro       # macro name: cora_gripper_xacro
        cora_gripper.ros2_control.xacro

The xacro macro must be named cora_gripper_xacro with params hardware_type and initial_positions_file.
Required joint names: Finger1 (prismatic, main) and Finger2 (prismatic, mimic).
Required dummy links and fixed joints: Gripper, Camera, Camera_optical with joints Gripper_frame, Camera_frame, Camera_frame_optical.
Launch with your package:

ros2 launch cora_bringup bringup.launch.py gripper_package:=your_gripper_description

Packages​

cora_common packages​

cora_robot packages​

ROS 2 Interfaces​

Topics​

Actions​

posegoal — cora_msgs/action/PoseGoal​

arm_controller/follow_joint_trajectory — control_msgs/action/FollowJointTrajectory​

gripper_fingers_controller/gripper_cmd — control_msgs/action/GripperCommand​

Services​

MoveIt Servo​

Lifecycle nodes​

MoveIt 2 (via move_group)​

Custom message definitions​

cora_msgs/msg/TargetedPoseStamped​

SRDF — planning groups and named states​

Launch files​

bringup.launch.py​

move.launch.py​

vision.launch.py​

gazebo.launch.py​

Simulation​

Installation​

Usage​

Real Robot​

ODrive Setup​

Installation​

Usage​

Adding a Custom Gripper​

Packages

cora_common packages

cora_robot packages

ROS 2 Interfaces

Topics

Actions

`posegoal` — `cora_msgs/action/PoseGoal`

`arm_controller/follow_joint_trajectory` — `control_msgs/action/FollowJointTrajectory`

`gripper_fingers_controller/gripper_cmd` — `control_msgs/action/GripperCommand`

Services

MoveIt Servo

Lifecycle nodes

MoveIt 2 (via `move_group`)

Custom message definitions

`cora_msgs/msg/TargetedPoseStamped`

SRDF — planning groups and named states

Launch files

`bringup.launch.py`

`move.launch.py`

`vision.launch.py`

`gazebo.launch.py`

Simulation

Installation

Usage

Real Robot

ODrive Setup

Installation

Usage

Adding a Custom Gripper