Gain Scheduling for the Orion Launch Abort Vehicle Controller

One of NASA’s challenges for the Orion vehicle is the control system design for the Launch Abort Vehicle (LAV), which is required to abort safely at any time during the atmospheric ascent portion of ight. The focus of this paper is the gain design and tuning process for a controller that covers the wide range of vehicle ight conditions and guidance phases experienced during the full envelope of potential abort trajectories from the pad to exo-atmospheric ight. Several factors are taken into account for tuning the gains including the eectors, the environmental changes and the autopilot modes. Tuning the gains is accomplished using a linear quadratic regulator approach for a simplied linear model throughout the operational envelope in time, altitude and Mach number. The derived gains are then implemented into the full linear model for controller requirement validation. Finally, the gains are tested and evaluated in a non-linear simulation using the vehicle’s ight software to ensure performance requirements are met. An overview of the LAV controller design and a description of the linear plant models are presented. Examples of the most signicant challenges with the automation of the gain tuning process are then discussed. In conclusion, the paper explains the lessons learned throughout the process, especially with regards to automation, and examines the usefulness of the gain scheduling tool and process to non-Orion vehicles.