ROS 2 DDS to NGSI-LD Architecture

This document describes the active telemetry ingestion path used by ROBIN.

Baseline

ROBIN uses a DDS-first flow:

1. ROS topics are aggregated into a single telemetry message (ProcessTelemetry)

2. Orion-LD DDS module maps that topic into a Process entity attribute

3. TROE + Mintaka provide temporal history

Legacy HTTP NGSI bridge is not part of this architecture.

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Data Flow

        graph LR
  A["ROS topics"] --> B["telemetry_aggregator_node"]
  B --> C["/robin/telemetry"]
  C --> D["Orion-LD DDS module"]
  D --> E["urn:ngsi-ld:Process:ros_bridge"]
  E --> F["TROE / TimescaleDB"]
  F --> G["Mintaka"]
    

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ROS Layer

Telemetry message

• File: vulcanexus_ws/src/robin_interfaces/msg/ProcessTelemetry.msg

• Purpose: package geometry + machine + pose values into DDS-friendly primitive fields

Aggregation node

• File: vulcanexus_ws/src/robin_core_data/scripts/telemetry_aggregator_node.py

• Publishes: /robin/telemetry

• Inputs: geometry, fronius/welder data, pose topics

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Orion DDS Mapping

Configuration file: config-dds.json

The mapping connects DDS topic rt/robin/telemetry to entity urn:ngsi-ld:Process:ros_bridge with attribute urn:robin:processTelemetry.

See Configuration Reference for the full JSON and environment variable details.

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Validation Steps

# 1) Verify telemetry topic exists
ros2 topic echo /robin/telemetry

# 2) Verify Orion process entity
curl -H "NGSILD-Tenant: robin" \
  "http://localhost:1026/ngsi-ld/v1/entities/urn:ngsi-ld:Process:ros_bridge"

# 3) Verify temporal history via Mintaka
curl -H "NGSILD-Tenant: robin" \
  "http://localhost:9090/temporal/entities/urn:ngsi-ld:Process:ros_bridge?lastN=5"

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Notes

• Keep ROS and Orion DDS domains aligned (ROS_DOMAIN_ID).

• Use host networking for DDS discovery where required by deployment.

• Prefer flat numeric fields in telemetry messages for robust DDS-to-NGSI mapping.