RTEMS Improvement – Real Time Operating System (RTOS) for UAVs


RTEMS Improvement, Real-Time Executive for Multiprocessor Systems, is a free open source real-time operating system (RTOS) designed for embedded systems. The RTEMS system presented here has been adapted to implement a basic certifiable Health Monitoring System (HMS) focused principally on applications in UAV Ground Control Stations. The results showed RTEMS could be a cost-effective solution for almost any kind of safety-critical embedded Software application in Aeronautics, Railway and Automotive applications.


The different parts of the technology offer can be defined as follows:

  • The Stimulation block is the STANAG message generator, stimulating UAV real telemetry.
  • The critical block is the core HMS application. It is a modified RTEMS Improvement running on LEON3 architecture. The system processes the telemetry and generates ARINC-661 compliant packets.
  • The HMI block consists of the visualization of Telemetry data, based on a standard ARINC-661 Definition File, updated in real time with incoming data from RTEMS.

Innovations and advantages of the offer

RTEMS Improvement is a certified Real-Time Operating System (RTOS), which has been used widely in Space projects. This is a qualified version that does not include BSD Net Stack or Drivers for peripherals. A demonstrator has been constructed to:

  • Assess the viability of RTEMS for UAV critical systems
  • Simulate an Air-to-Ground application

The application chosen was a Health Monitoring System (HMS). The demonstrator implemented a basic certifiable HMS for a UAV Ground Control Station.  In order to get a realistic, close-to-market environment, the HMS application was designed to be driven by flight-proven telemetry transmitted from an industrial UAV.

Airbus Defence and Space provided a simulation record of ATLANTE aircraft STANAG telemetry, ensuring that the software was fully aligned with a real‐life, medium‐sized unmanned aircraft application.

The RTEMS Improvement does not include drivers for any peripheral or the BSD TCP/IP stack, which required that the ETHERNET driver and UDP/IP stack were created from scratch.

The RTEMS Improvement has been confirmed as a cost-effective RTOS alternative for critical UAV applications, with the advantages of:

  • Low cost
  • Small memory footprint
  • Modular implementation

Lack of Ethernet and TCP/IP stack support is an issue that has to be overcome with custom solutions, but this is also the case for more expensive systems. The final tests in ATLANTE were successfully conducted in October 2014, building on the foundation of the HMS test, which fully validated the potential integration.


Space-qualified RTEMS system

  • Currently adapted for use as a Health Monitoring system for UAV ground control system.
  • Low cost system

Potential applications:

  • Raliway Signalling safety-critical Operating System
  • Avionics embedded system (FCS, Cargo Management, Comms Management) Operating System
  • Automotive ADAS Operating System

Comments on the technology by the broker

This technology is an adaptation of the space qualified RTEMS Improvement system and was developed under ESA contract.  Orbital Aerospace has also contributed to the Ultra Violet Atmospheric Sounder (UVAS) mission as part of the Complementary Science Payload (CSP) on board the SEOSAT satellite. Its partnership in this project involved the design of the Spectrometer Electric Box (SEB). The system on-board application software was designed to run on the RTEMS operating system, using LEON2 processor architecture.

Description of Space Heritage

RTEMS Improvement, Real-Time Executive for Multiprocessor Systems, is a free open source real-time operating system (RTOS) designed for embedded systems. It has been widely used in Space projects:

  • NASA Mars Reconnaissance Orbiter's Electra Radio (Software-Defined Radio) runs RTEMS on SPARC V7 processors
  • ESA Herschel Space Telescope runs RTEMS on SPARC V7 processors.
  • ESA Lisa Pathfinder Data Management Unit (DMU) runs RTEMS on two redundant ERC32SC SPARC processors.

RTEMS Improvement was developed by Edisoft (Portugal) under ESA/ESTEC Contract number 21141/07/NL/JD.

Computer Hardware & Software
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Could this technology benefit your business? Please contact Richard Seddon Tecnalia (Spain)
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