Verification and Validation of Spacecraft Embedded Software

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• Verification and Validation of Spacecraft
  Embedded Software

Presented by Mike Rennie Director of Real-Time
Systems DEIMOS Space S.L. (Madrid, Spain)
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VV of Spacecraft Embedded SW
Contents

• Parent-Child Object Integration Tests
• Single Thread Integration Tests
• Multiple Thread Integration Tests
• Software Validation on a Real-Time Test Bench

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Parent-Child Object Integration Tests

• Incremental, bottom-up integration of
  parent-child object hierarchy
• Test cases described using UML sequence diagrams,
  showing the call from test driver to parent to
  child operations

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Single Thread Integration Tests

• Execution invoked at threads root, verifying
  that it follows the expected path and that all
  objects and operations along that path
  collaborated correctly
• Each thread tested in isolation of all the other
  concurrent threads
• Compile modules that are within the call tree of
  the thread
• Stub out all synchronization calls and rendezvous
  with other threads
• Test driver calls visible operations to control
  the execution
• Other objects needed only to compile and link the
  main programme are also stubbed
• Stubs write trace messages to standard output
• First and last statement of every operation in
  the SW-under-test is a call to a marker
  function, that gives a trace of the call sequence

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Structure of a Test Programme for Single-Thread
Integration
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• Call Tree Coverage Analysis for Single-Thread
  Integration
• Intended code coverage depicted by displaying the
  threads call tree with the operations that were
  intended to be exercised in green, stubs in grey,
  and untested calls in white

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Multiple Thread Integration Tests

• Objective to verify real-time behaviour of
  concurrent tasks co-operating together to
  implement a major functionality. In particular,
  exchange of data between control flows. Thus,
  selection of test cases relies on identifying
  communication paths between threads.

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Communication Path via a Protected Object in
HRT-HOOD
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• Software Validation on a Real-Time Test Bench
• A real-time test bench typically consists of
• Onboard computer (or emulation)
• Emulation of the communications
  (telecommand/telemetry) link between Ground and
  Spacecraft
• Simulation of the environment surrounding the
  onboard computer (actuators, sensors, space
  environment)
• Hardware-in-the-loop, i.e. real sensors and/or
  actuators
• Example (PACS)