ATV - Simulations Development

The Automated Transfer Vehicle (ATV) is one of Europe’s contributions to the International Space Station (ISS). VEGA is developing the ATV numerical models for EADS Space Transportation.

Challenge

Throughout the development of the ATV a number of non real-time and real-time simulators are being used to validate the design, the functionality of the flight software and the functional qualification of the ATV vehicle. This qualification is performed by verifying the on-board software integrated in a complete system environment functionality (hardware-in-the-loop).

 

How VEGA helped

VEGA is developing the ATV numerical models for EADS Space Transportation. The real-time simulator MATLAB™/SIMULINK™ was chosen as the development tool to generate the so-called numerical models. The EuroSim™ was selected as the simulator platform. The development of the ATV numerical models is based on the classical ‘V’ lifecycle. The SIMULINK and EuroSim tools cover all the cycle activities.

 

In order to fulfil the needs of the real-time and non real-time simulators a number of numerical models have been developed, which:

 

  • Replace the missing 1553 RT equipment (in the case of equipment redundancy not integrated into the electrical mock up of the vehicle)
  • Stimulate the real equipment through so-called front-end equipment in order to make this equipment provide correct data when read by the Flight Software
  • Model the behaviour of the external systems interfacing with the vehicle (GPS constellation, TDRS, ISS)
  • Archive all data needed for post processing analysis

 

The only common element in all the simulators is a set of numerical models. These numerical models are used to simulate hardware-in-the-loop, replace missing hardware, or to simulate the environment.

 

For ATV the MATLAB/SIMULINK tools have been selected for the model specification, design and development, as such the tool is used throughout the whole life-cycle. Although it does not follow a particular methodology, it offers most of the benefits of a CASE tool and also supports the execution of the models within it.

 

Although MATLAB/SIMULINK is not object-orientated, it was recognised that some of the benefits of object-orientated design could be achieved by using SIMULINK in a particular way. This has been given the name: Function Orientated Design. With this design it was possible to achieve all the expected performance results, deliver on time and budget and fulfil all software requirements.

 

Project status

The Software Validation Facility and Flight Segment Facility Simulators are currently in use. Both simulators are using the developed models and show measurable results. All models run in ‘hard real-time’ and no major non-conformances could be found. The Models will be modified and reused for the Ground Segment Simulation Training Facilities.