Projectile Ascent Trajectory Using Moving Mass Control

Abstract

The current best technology to reach orbit is rocketry - but there may be under-explored solutions that provide cheaper, less complex, and more environmentally- friendly access to space. Impulse launchers have the potential to achieve these three criteria. This study seeks to control such an ascent vehicle - originating from a linear impulse launcher - using a moving mass as the sole source of actuation. The system non-linearities necessitate the use of gain scheduling to account for the vast changes in Mach number and altitude. A gain-scheduled PID control look-up table is constructed under a list of time and frequency domain stability criteria. Two potential ascent trajectories are explored: an aggressive approach which minimizes vehicle mass and ascent time, and an orbit-conscious approach which minimizes the velocity correction requirement to enter orbit. Simulations provide a proof of concept for vehicles achieving orbital velocities at the Karman Line when launched at Mach 30. However, limitations in effectiveness at high altitudes prevent the vehicle from entering orbit with a moving mass alone.