Synthesizing an algorithm to control the angular motion of spacecraft equipped with an aeromagnetic deorbiting system

Abstract

It is known that the synthesis of the relevant control law is performed and appropriate control devices are selected for specific tasks of controlling relative spacecraft motion. Flywheels, control moment gyroscopes, electromagnetic devices with permanent magnets and micro-jet engines are used as actuators in controlling the orientation and stabilizing the spacecraft. For example, flywheel motors together with electromagnets are most often used to ensure precise spacecraft stabilization in remote Earth monitoring (REM) problems. At the same time, there is a series of problems pertaining to the control over the relative motion of spacecraft where there is no need for precise spacecraft stabilization and ensuring minimal errors in orientation. These problems may include spacecraft orientation for charging solar batteries or orientation control for research and meteorological spacecraft.The study's purpose is to synthesize a law for spacecraft orientation control algorithm when using executive devices with permanent magnets (EDPM). EDPMs are the devices controlling spacecraft orientation. They consist of rotary permanent magnets, stepper motors, and capsule-screens with shutter flaps. Opening and closure of the capsule-screen flaps and rotation of permanent magnets in a certain way ensure the generation of a discrete control magnetic moment. It should be noted that EDPMs do not provide accurate spacecraft stabilization and hence they are not suitable for the REM purpose. However, EDPMs consume less on-board energy than other spacecraft orientation control systems and are useful in problems requiring less accurate stabilization.A control law was synthesized for controlling spacecraft equipped with EDPM using a nonlinear controller and a pulse-width modulator. Areas of effective EDPM application for various space-related problems including orientation and stabilization of aerodynamic elements perpendicular to the dynamic flow of the incoming atmosphere were determined. Advantages of using EDPMs in comparison with electromagnetic executive devices in the problems pertaining aerodynamic element stabilization in aerodynamic systems of deorbiting worked-out spacecraft from low Earth orbits were shown.