Features of Attitude Control of a Spacecraft, Equipped with Inertial Actuators

Abstract

The topic of the article is the problem of the correct selection of time for an optimal spacecraft turn from any initial position to the prescribed final angular position. The case, when a spacecraft is rotated with a minimal magnitude of the angular momentum, is considered. The optimal control is within the class of the regular motions. It is assumed that the dynamics of the spacecraft rotation during a turn corresponds to the well-known control method [1], which includes a maximal possible acceleration of rotation of a spacecraft, rotation with constant module of angular momentum and the maximal possible slowing down of the angular momentum. At the acceleration and braking phases the control moment is the greatest possible and is parallel to the spacecraft angular momentum; between the acceleration and braking phases the controlling moment is formed from the condition that spacecraft motion occurred strictly along the appointed trajectory of rotation defined by computational turn vector and a preset value of the modulus of the angular momentum. Formalized equations are presented, and computational expressions for definition of the optimal duration of reorientation maneuver are derived for the known mass-inertial characteristics of a spacecraft, if the attitude control is implemented with the use of the inertial actuators (system of powered gyroscopes, gyrodynes). The condition for determination of the moment of the beginning of the braking, which uses the current parameters of motion (information on the angular position of a spacecraft and measurements of the angular velocity) is presented, which increases considerably the accuracy of spacecraft movement to the required position. This paper is continuation of [1, 2].