Active Magnetic Control Methods for Small Satellite

Abstract

A small satellite is likely to tumble as the result of separating from the rocket. It is therefore very important to capture it promptly with finite magnetic torque. Magnetic torque is orthogonal to the external magnetic field; therefore, it is impossible to generate precisely the control torque that would be required according to simple control theories. However, it is possible to define the desirable torque first and then derive from this the actual control torque. A criteria is presented for this derivation and two control algorithms are formulated, based on nonlinear design theories. One is the energy method that takes the Lyapunov function as a control criteria and uses a divided districts control algorithm to determine the desirable torque. The other one uses the variable structure control method to define the desirable torque. The results of computer simulation indicated that these algorithms have the advantages of excellent robustness and are easily designed and realized.