Titan flight software quality enhancement

Abstract

The flight software of a launch vehicle plays an important role in the success of a space mission to inject one or more spacecraft into earth orbit. Total Quality Management of both flight software development process and product is essential to reduce cost, increase reliability, improve customer satisfaction, and enhance quality and robustness of a launch vehicle system. Both Deming and Taguchi emphasized the use of statistical tools and testing for effective management and continuous quality improvement of a product. It is demonstrated that addition of a new nodal crossing prediction algorithm into Commercial Titan flight software effectively increased the robustness of the launch vehicle system and improved the park orbit injection accuracy for the spacecraft. The purpose of this paper is to present an overview of flight software life cycle, quality enhancement and management, and use of a statistical approach to optimize the guidance parameters. * Unit Head, Guidance Analysis and Software Validation 1.0 INTRODUCTION Copyright (C) 1989 Martin Marietta Cor~oration To achieve successful space missions, the launch vehicle must be designed and tested for quality and reliability of each component. Although the quality engineering control has been instituted in every level of manufacturing of each hardware component, less attention has been paid to quality control at the system engineering level, which includes software engineering. A total system quality control encompasses the design, manufacturing, and customer feedback to provide a continuous quality improvement. Recently, the Department of Defense (DoD) has issued a Total Quality Management (TQM) initiative1 to its contractors, and their vendors for continuously improving their performance at every level by a DoD vision, which is articulated in principle, and achieved in practice through specific techniques and tools. Several quality circles such as the Shewhart cycle2 have been suggested to emphasize this continuous process of product improvement. Genichi ~ a ~ u c h i ~ divides the system quality engineering into two parts: 1) On-line quality control, and 2) Off-line quality control. Both on-line and off-line quality controls are intended for the consistency of meeting customer requirements. On-line quality control has been implemented industry-wide to ensure that the hardware meets specifications. Off-line quality n Published by the AIAA, INC. with permission. control is needed to ensure that the software design and test satisfy the requirements. Quality control of flight software plays an important role in the success of a launch vehicle mission. The purpose of this paper is to provide an overview of flight software quality enhancements and use of a statistical approach to optimize the parameters.