Boundary points and arcs in constrained, time-optimal satellite reorientation maneuvers

Previous work on time-optimal satellite slewing maneuvers, with one satellite axis (sensor axis) required to obey multiple path constraints (keep-out cones centered on high-intensity astronomical sources) revealed complex motions with no part of the solution touching the constraint boundaries (boundary points) or lying along a finite arc of the constraint boundary (boundary arcs). This paper examines four cases in which the sensor axis is either forced to follow a boundary arc, or has initial and final directions that lie on the constraint boundary. Numerical solutions, generated via a Legendre pseudospectral method, show that the forced boundary arcs are sub-optimal. Precession created by the control torques, moving the sensor axis away from the constraint boundary, results in faster slewing maneuvers.