ROS 2 architecture
Joint names, units, and frames: small contracts with large consequences
By NOVEMIQ · Engineering explainer
Robot software components must agree on the meaning of state. Correctly delivered numbers can still be wrong for an application if units, joint names, or coordinate conventions differ.
- 01Named joint
- 02Defined quantity
- 03Known reference
- 04Consumer agreement
Understand the boundary
At each interface, document the semantic meaning of a value as well as its type. Confirm whether the consumer expects joint position, velocity, or another state, and how that state maps to the robot model.
What to review
Use an interface review to catch mismatched naming and conversions before motion testing. Include the origin of each measurement and its timestamp. Avoid silently repairing inconsistent data in several downstream components.
Put it into practice
For an illustrative arm integration, trace one measured joint value from hardware readout to the application display. Document each transformation. Repeat with commanded values in the opposite direction before validating coordinated behavior.
Technical reference
ros2_control hardware interfaces. Consult documentation for your selected software version before implementation.
Continue reading
- What robotics software engineering services should deliver
- Before benchmarking robot motion, define the experiment
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