ABSTRACT
All designs in Chapter 9 calculate the desired torques which are used to control the spacecraft attitude. These desired torques are supplied by using several different actuators or their combinations. Chapter 10 discusses different actuators. Section 10.1 introduces reaction wheels and momentum wheels. Section 10.2 describes the control moment gyros (CMG) and variable speed control moment gyros (VSCMG). Section 10.4 discusses magnetic torque rods. Section 10.5 considers thrusters. It is worthwhile to note that only reaction wheels and momentum wheels can provide all desired torques with only the restriction of saturation. Control moment gyros have singular points where CMG cannot provide desired torque. Magnetic torque rods can provide torques in two-dimensional space while the desired torques are most likely in three dimensionals space. Torques provided by thrusters depend on thruster configuration. Therefore, Chapters 11–15 present some design methods that are developed specifically for spacecraft control systems that use these specific actuators.
