Spiral Lifecycle Increment Modeling for New Hybrid Processes

Abstract

The spiral lifecycle is being extended to address new challenges for Software-Intensive Systems of Systems (SISOS), such as coping with rapid change while simultaneously assuring high dependability. A hybrid plan-driven and agile process has been outlined to address these conflicting challenges with the need to rapidly field incremental capabilities. A system dynamics model has been developed to assess the incremental hybrid process and support project decision-making. It estimates cost and schedule for multiple increments of a hybrid process that uses three specialized teams. It considers changes due to external volatility and feedback from user-driven change requests, and dynamically re-estimates and allocates resources in response to the volatility. Deferral policies and team sizes can be experimented with, and it includes tradeoff functions between cost and the timing of changes within and across increments, length of deferral delays, and others. Both the hybrid process and simulation model are being evolved on a very large scale incremental project and other potential pilots.