Spacecraft Re-Entry Control Using Cross and Radial Moving-Mass Actuators

Abstract

This study explores the control of a space capsule during the re-entry phase. Spacecraft re-entry is a critical phase of a mission because, as the spacecraft enters Earth's atmosphere, aerodynamic forces and moments can disturb the angles of attack and sideslip, potentially leading to instability. If left uncontrolled, these disturbances can cause significant damage to the spacecraft and jeopardize the safety of its passengers.To mitigate these disturbances, moving mass controllers (MMC) are employed as efficient actuators. MMCs control the spacecraft by altering its center of mass and generating internal forces. The primary advantage of MMCs over other control methods, such as aerodynamic surfaces and thrust jets, is that they do not produce turbulent aerodynamic forces, which can impair the controller's performance.A vital aspect of this research is the design and analysis of the moving mass controller mechanisms. In addition to examining the more standard cross mechanism, this study also investigates the radial mechanism. The radial mechanism offers advantages over the cross mechanism, such as increased load-carrying capacity. Under the same conditions, the radial mechanism can reduce the mass of the actuators by half. Due to the nonlinear relationships governing the radial mechanism, a nonlinear controller is necessary. This study employs a nonlinear proportional-integral-derivative (PID) controller, demonstrating high efficiency.

Keywords

• space capsule: re
• entry: suborbital: moving mass: stability: control