MOVING MASS TRIM CONTROL FOR AEROSPACE VEHICLES

A moving mass trim controller is proposed to increase the accuracy of axisymmetric, ballistic vehicles. The moving mass trim controller diff ers from other moving mass schemes because it generates an angle of at tack directly from the mass motion. The nonlinear equations of motion for a ballistic vehicle with one moving point mass are derived and pro vide the basis for a detailed simulation model. The nonlinear equation s are linearized to produce a set of linear, time-varying autopilot eq uations. These autopilot equations are analyzed and used to develop th eoretical design tools for the creation of moving mass trim controller s for both fast and slow spinning vehicles. A fast spinning moving mas s trim controller is designed for a generic artillery rocket that uses principal axis misalignment to generate a trim angle of attack. A slo w spinning moving mass trim controller is designed for a generic re-en try vehicle that generates a trim angle of attack with a center of mas s offset and aerodynamic drag. The performance of both moving mass tri m controllers are evaluated with the detailed simulation.