Robot Joint States: Preserve Name and Array Alignment
Review JointState name alignment, optional arrays, units and common acquisition time before robot joint values enter displays or calculations. This guide concerns robot integration and delivery review. The proposed observations are editorial assessment guidance, grounded in the linked original documentation and subject to the deployed version. They do not describe an on-site test of a particular machine or establish whole-system acceptance from a single interface response.
Associate state through joint names
The definition identifies joints by name and associates state arrays by position. Retain actual names and arrays rather than assuming every driver uses one fixed ordering. If a consumer requires a different internal order, define an explicit name mapping so index-only copying does not display one joint’s state as another joint’s measurement.
For this review, identify the delivered device, software and configuration revisions first. Record unsupported, disabled and untested capabilities separately. Evidence from another model is useful context, but cannot establish what the delivered combination actually provides. Keep the original input beside the settings used to interpret it.
Check equal-size or empty arrays
The definition permits empty state arrays where no corresponding quantity is supplied, while populated arrays must remain associable with names. Empty effort does not mean measured zero effort at every joint. Preserve availability rather than filling missing fields with zeros simply to make a chart rectangular and imply observations the device never supplied.
Retain the original input and the reason for the decision, rather than a successful screenshot alone. Change only the variables agreed for the comparison, and keep the before-and-after configuration. List conditions that were not exercised explicitly; they should not silently become part of the accepted operating range.
Interpret units by joint type
Revolute and prismatic joints use different position, velocity and effort units. Associate them with the robot model and driver contract. Identical field names cannot replace a joint-type review. Retain type and numeric association together so a unit conversion in one column does not leave related state or model interfaces with an unexplained interpretation.
Use the three illustrated observations as starting questions, rather than as diagnoses of an installation that has not been inspected. Check record completeness, units and identity before selecting the next observation. An unresolved result is more informative than a confident explanation assembled from missing fields or unrelated test runs.
Review the common acquisition-time contract
The definition requires states in one message to be recorded at the same time, represented by the header. If a driver combines inputs from different cycles, document alignment or estimation. Assembly time alone cannot establish simultaneous physical acquisition. Retain original sources and combination rules so consumers can judge the resulting message’s actual scope.
Let the site owner choose an approved isolated way to exercise relevant exceptions. Record normal operation, the exceptional condition and recovery separately. The purpose is to establish how the application recognises and explains untrustworthy input, without requiring production equipment to act on deliberately invalid results.
Deliver alignment and availability evidence
Deliver name mapping, array samples, units, acquisition-time meaning and missing-field treatment, identifying unreviewed joints. Recheck ordering after driver or model changes. Parsing success and smooth curves cannot establish correct association. A maintainer should be able to trace any displayed value to its named joint, original array element and recorded time.
Deliver the configuration, representative samples, result table and unresolved questions together. Agree who reviews subsequent changes. The receiving team should be able to select one conclusion and trace it back to its input and decision path without relying on the original author to reconstruct the missing steps.
Original documentation and further reading
Continue with related articles in this section, or use selection guides to prepare the next review. Apply the device-specific documentation and agreed operating conditions when implementing a test.