This document discusses how to reduce safety certification costs for unmanned aircraft systems using a certifiable version of the Data Distribution Service (DDS) middleware. It describes how DDS can provide open standards-based communication for UAS networks. The key points are that RTI has developed Connext DDS Cert, a small-footprint, deterministic implementation of DDS that is certifiable to DO-178C Level A. Its minimal lines of code and reusable certification evidence allow users to cut $2M or more from certification costs compared to traditional approaches.

1. Your systems.
Working as one.
How to Cut $2M of Your Safety
Certification Costs
Edwin de Jong, PhD

2. Modern Unmanned Aircraft Systems
• Network of
– Multiple Unmanned Aerial Vehicles (UAVs)
– Multiple Ground Control Stations (GCS’s)
– Configurable payloads and smart sensors
• Multiple and changing mission
objectives
• Challenge:
– Make data and capabilities of smart sensors
accessible to every relevant participant
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3. UAS Communication Infrastructure
Vehicle LAN
Data Link
Ground Station LAN
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4. Baseline Capabilities for UAS
Communication Infrastructure
• Open standards based
– Commonality and interoperability
• True peer-to-peer architecture
– No single point of failure or vulnerability
• Portable to any communication media
– RF, optical links, high-speed interconnects
• Available for heterogeneous environments
– Embedded, low-power, small foot-print, RTOS, ARINC 653
– Mainstream OS’s (Windows, Linux) and CPUs (Intel)
• Certifiable component (DO-178C)
– Integration of UAVs in national airspace
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5. Peer‐To‐Peer Real‐Time DataBus
OMG Data Distribution Service
Control
App
Commands
Sensor
Sensor Data
ActuatorSensor
Sensor Data
Display
App
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6. Data‐Centric Integration
Distributed Data Model and System State
Source
(Key)
Latitude Longitude Altitude
RADAR1 37.4 -122.0 500.0
UAV2 40.7 -74.0 250.0
LPD3 50.2 -0.7 0.0
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7. Hundreds Of Applications Rely on DDS
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8. DO‐178C
• A guideline
• Used by FAA as basis
for certification
– Aircraft are “certified”
– Software code
developed under
DO‐178 provides “certification evidence”
• Increasingly adopted for military aircraft
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9. DO‐178 Safety Levels
Level Failure Condition
Typical % of
avionics code
A
Catastrophic
(may be total loss of aircraft)
15%
B
Hazardous/Severe
(serious injuries)
35%
C
Major
(minor injuries)
30%
D
Minor
(inconvenience)
15%
E No effect 5%
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10. Certification Costs
• DO‐178 costs $50‐$100
per ELOC
• Process objectives must
be met
• All must be documented
• Code must be clean
– Testable
– No dead code
– Deterministic
Level Process
Objectives
Code Coverage
A 71
Level B and 100% of
MCDC
B 69
Level C plus 100% of
DC
C 62
Level D plus 100%
of SC
D 26
100% of
Requirements
E 0 None
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11. Tenets Of Safety‐Critical Software
• Reduce code size
• Consider testability in design
• Design code to be deterministic
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12. Communication‐Middleware Implications
• Specific implementation with
fewer capabilities
– Reduced ELOC
• Predictable
– No dynamic memory allocation
– Applications preconfigured
• Limited size of distributed system
– Suiting most avionics systems
– Larger size system integration through bridge
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13. Reducing Middleware Size
• Use efficient data structures
– Optimized for smaller‐scale systems
– Simpler data structures allow middleware to
remain small even as new functionality is added
• Balance capabilities versus size
– Include capabilities relevant in safety‐critical
systems only
– Focus on core capabilities
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14. Safety‐Certifiable Communication Platform
• Scalable product line
for constrained
environments
• Certifiable component
– DO‐178C Level A
– ~25K ELOC
• Follows OMG DDS specification
• FACE compliant interface in development
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15. Certifiable DDS – Core Capabilities
• Support for multiple
domains
• Domain Participant
Factory
– Create/delete Domain
Participants
• Domain Participant
– Create topics (keyed and
keyless)
– Create publications
– Create subscriptions
– Delete contained entities
• Subscription
– Polling
– Notification
– Read/take
• Publication
– Write with or without
timestamp
– Dispose
– Liveliness
• Thread-safe
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16. Memory Model
Application
Network
DDS middleware
Data Cache
Discovery
Database
Grows as
more data
produced
Grows as
more nodes
join
Configure resource limits before creating entities
No memory growth
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17. Quality of Service (QoS) Support
• Communication protocols
– Best effort
– Reliable with periodic and piggyback heartbeats
• Optional durability
– Last value kept in‐memory by publisher
• Send/receive cache resource configuration
• Publication and subscription deadline
• Ownership and strength
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18. DDS Discovery
Peer 1 (up)
Peer 2 (down)
Initial peers:
Peer 1
Peer 2
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19. DDS Discovery – Stage 2
Peer 1 (up)
Peer 2 (down)
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20. Discovery for Safety‐Critical Systems
Unknown number of participants connecting
Unknown number of remote endpoints
Know which participants are up
Simple protocol
Stage 1: dynamic participant discovery
Stage 2: static loading of endpoints
Quasi‐static discovery
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21. Certification Evidence
• Plan for Software Aspects of
Certification (PSAC)
• Software Development Plan (SDP)
– Requirements standards
– Design standards
– Code standards
• Software Verification Plan (SVP)
• Software Configuration
Management Plan (SCM)
• Software Quality Assurance Plan
• Software Requirements Data
• Design Description
• Traceability
• SQA Records
• SCM Records
• Software Configuration Index
• Software Verification Cases and
Procedures
• Software Verification Results
• Software Accomplishment
Summary
Certification evidence can be re‐used across programs
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22. Savings from DDS Certification Evidence
30,000 ELOC 20,000 ELOC 10,000 ELOC
Level A $3,000,000 $2,000,000 $1,000,000
Level B $2,550,000 $1,700,000 $850,000
Level C $1,800,000 $1,200,000 $600,000
• DDS certification evidence available at fraction
of cost
• Availability at start of project also reduces risk
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23. Summary
• Certifiable DDS designed for safety‐critical
applications now available
– Connext DDS Cert
– Standards compliant
– Small footprint
• Code is certifiable to DO‐178 Level A
– Minimal lines of code
– Deterministic
• Certification evidence is reusable
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24. Your systems.
Working as one.
Download
Connext
Free Trial
NOW
www.rti.com/downloads

25. Thank you