Closed-loop magnetic control of a spin-stabilized satellite

Autonomous closed-loop magnetic control is achievable for a spinning satellite in a near magnetically polar orbit for maintaining a programmed spin rate and a spin pointing-axis normal to the orbit plane. 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 between the earth sensor pulses and detect errors in spin rate and pointing elevation angles between the spin axis and the horizontal (roll). Programmed altitude corrections to these timing measurements are required for non-circular orbits. In addition, the electronics make sequenced samples of the magnetometer signals, perform the control law logic, and command the electrical connections to energize the magnetic coils. The spin control generates magnetic torque when the field is detected in the appropriate direction to provide spin torque in the direction to correct spin rate.