  A fundamental capability for On-orbit Servicing, Assembly, and Manufacturing
(OSAM) is inspection of the vehicle to be serviced, or the structure being
assembled. This research assumes autonomous slewing to maintain situational
awareness of multiple vehicles operating in close proximity where several
safety constraints must be satisfied. A variety of techniques may be used as
the primary controller. The focus of this research is developing Run Time
Assurance (RTA) filters that monitor system behavior and the output of the
primary controller to enforce safety constraint satisfaction. Specifically,
this research explores combining a subset of the constraints into an Active Set
Invariance Filter (ASIF) RTA defined using control barrier functions. This
method is minimally invasive to the primary control by minimizing deviation
from the desired control output of the primary controller, while simultaneously
enforcing all safety constraints. The RTA is designed to ensure the spacecraft
maintains attitude requirements for communication and data transfer with a
ground station during scheduled communication windows, adheres to conical
attitude keep out zones, limits thermally unfavorable attitude duration,
maintains attitude requirements for sufficient power generation, ensures
maneuvers are below threshold to cause structural damage, ensures maximum
angular velocity is below limits to maintain ability to respond quickly to new
slewing commands, and conserves actuator use to prevent wear when possible.
Slack variables are introduced into the ASIF controller to prioritize safety
constraints when a solution to all safety constraints is infeasible. Monte
Carlo simulation results as well as plots of example cases are shown and
evaluated for a three degree of freedom spacecraft with reaction wheel attitude
control.
