Time-optimal multi-axis attitude maneuvers of rigid spacecraft using collocation and nonlinear programming

Spacecraft attitude control is an important aspect of satellite technology; in particular, time-optimal maneuvers are critical in military applications, communications satellites, and for scientific flyby missions. Although the problem is fairly easy to formulate, it has proved nearly impossible to solve, either numerically or analytically except in a few simplified cases. The thesis begins with a comprehensive survey of the literature of the last thirty years, from early attempts to solve the time-optimal reorientation problem to the latest approaches applied to flexible spacecraft. The background and details of a particular solution method, collocation and nonlinear programming, are discussed in detail. The discussion concludes with application and usage notes for using this method to solve time-optimal attitude maneuver problems. Applying the method of collocation and nonlinear programming to these maneuvers yields the solution of several classes of problems which have not been solvable by other means. This method has several advantages over traditional methods of solution: it is straightforward to formulate, it is easy to use and to modify, requires low computation times, and is extraordinarily robust with respect to the initial guess used to obtain a solution. The results obtained using this method are compared to known solutions, and show excellent agreement with them. Solutions for several additional spacecraft configurations and different maneuvers are presented, including rest-to-rest reorientations, detumble, and spin-up motions. The thesis concludes with a brief discussion of future developments for the method and the types of problems to which it might be applied.