Software Architecture of Sequentially Rotating Rigid Spacecraft Components Using the Backsubstitution Method

Spacecraft simulations and subsequent analyses are critical to verifying performance requirements in any mission development. With increasingly more complex spacecraft configurations, finding the fully coupled equations of motion and developing an integrated dynamics and flight software simulation architecture that configures such complex dynamics is difficult and often spacecraft-specific. Rotating appendages are a particularly interesting subcategory because they represent many common components, from spinning attitude control devices and flexible solar panels to robotic arms used to service and dock spacecraft. This work builds on the backsubstitution method (BSM), which introduced a modular and fast-to-execute framework to represent the equations of motion, assuming that the spacecraft comprises multiple effectors attached to a rigid hub. A novel modular software architecture enables the BSM simulation of any sequentially connected rotating appendages and the equations of motion that represent spacecraft with these components (or effectors). The rigid bodies can be connected by any sequence of single-axis rotations with any mass distribution or spin axis, vastly expanding the possible BSM spacecraft configurations and allowing for the simulation of complex effectors attached to a rigid hub under a common framework. Numerical examples of a flexible panel and a robotic arm illustrate the effectiveness of this modeling approach.