Closed Loop Magnetic Control of Spin Rate and Pointing Normal to the Orbit for a Polar Orbiting Spin Stabilized Satellite

Abstract

Autonomous closed loop magnetic control is achievable for a spinning satellite in an orbit inclined to the earth's magnetic field to control the spin pointing axis normal to the orbit plane and also the spin rate. The system requires a spin pointing coil to generate magnetic moments parallel to the spin axis, a spin rate coil with an axis normal to the spin vector, an earth sensor, a magnetometer measuring the earth field components normal to the spin, and electronic logic and circuitry to perform timing measurements. Earth sensor pulses are used to detect errors in spin rate and pointing elevation angles between the spin axis and the horizontal. Programmed altitude corrections to these timing measurements are required for noncircular orbits. The electronics take sequenced sampled data of the magnetometer signals, perform the control law logic and command the electrical connections to energize the magnetic coils. The spin control generates magnetic torques when the field is detected in the appropriate direction to provide spin torque in the direction to correct spin rate.