Assessment of a Space Shuttle trajectory evaluation system (DOLILU II).

摘要

DOLILU II is a ground control system that generates space shuttle's launch trajectories, first stage guidance commands and verifies whether the generated trajectories are safe for the flight. It is a safety critical system and a high degree of confidence in its safety and reliability must be gained through assessment. We addressed three issues related to its safety and reliability assessment. We developed a reliability assessment framework for DOLILU II system. We proposed techniques to speed up test case execution and designed methodologies for the generation of input conditions needed to test the system.; We used a Bayesian statistical framework for reliability assessment. Bayesian statistics uses knowledge about the system to be incorporated into the reliability model before testing. DOLILU II has been operational for nearly five years. We use this information when developing the reliability model. This information is introduced in the form of prior beliefs.; DOLILU II system requires an average time of 30 minutes for each test run. This translates into a large time period required for testing to demonstrate that DOLILU II exhibits the required failure rate. Vertical slicing, a semantic transformation technique, is used to prove the possibility of parallel execution and enhance each test case execution.; DOLILU II is an on-demand system. Many test trajectories are needed for its assessment. Regression methods were used to develop models for the generation of input data.