Using pseudospectral method to search for propellant-optimal trajectories of the International Space Station attitude control maneuvers

The paper discusses the problem of searching for propellant-optimal trajectories of the International Space Station (ISS) attitude control maneuvers involving spatial turns through large angles using attitude control jet thrusters. Development of such algorithms for controlling the ISS angular motion is currently a crucial task for Russian developers of the onboard software. In order to generate the optimal trajectory for the attitude control maneuver, the paper proposes to use the Lobatto pseudospectral method. This method allows stating the optimal control problem as a nonlinear mathematical programming problem which can be solved using the method of sequential quadratic programming. Simulation results demonstrated significant savings of attitude control thrusters propellant and life during station attitude control maneuvers in comparison with the algorithms that are currently used in the motion control system of the ISS Russian Segment.