Device for controlling the retention of space satellites with the use of the geomagnetic field

摘要

1285919 Automatic control of satellites TOKYO SHIBAURA ELECTRIC CO Ltd 25 Sept 1969 [27 Sept 1968 (2)] 47227/69 Heading G3R The vector senses of attitude, attitude error and ambient geomagnetic field are combined to determine the necessary sense of operation of a reversing switch controlling the energization of a coil fixed to the satellite so that it corrects the error by interaction with the geomagnetic field. In Fig. 3, a sensor 303, such as a gyroscope, horizon sensor, sun sensor or star tracker carried by an earth orbiting satellite produces a signal dependent on the attitude of the spin axis of the satellite. A reference signal is produced by a gyroscopic or a sun, star or earth seeking device 302 which is set to correspond with a desired attitude of the satellite. A signal representing the difference between moments of inertia of the satellite relative to the actual and desired attitudes is derived from the above signals at 307 and applied to a computer 304 together with a signal representing the direction of the ambient geomagnetic field derived from a magnetometer 301 and the signal representing the attitude of the satellite from sensor 303. Computer 304 calculates from its inputs a function the sign of which determines the position of a reversing relay 308 controlling the energization of a coil 310 having an axis coincident with the spin axis of the satellite. As a result a current is applied alternately in one sense and the other to maintain the satellite in a desired attitude. In a modification, the coil current variations during orbit are controlled by a digital programmer which is periodically updated, e.g. once per orbit, by signals transmitted to the satellite from a computer on the ground. At the same frequency, e.g. once per orbit, signals from an attitude sensor transmitted from the satellite, and data on the orbit, location and speed of the satellite derived from a tracking radar, are applied to update simulators in the computer on the ground. Immediately after each updating of the programmer in the satellite, the computer predicts from that programme, which is stored, and the latest orbital and attitude data, the programme of coil current variations which will be transmitted at the next updating of the programmer in the satellite.