Suborbital vehicle re-entry dynamic inversion controller design and control allocation research

Abstract

To solve the re-entry control problem of suborbital vehicle, which has a large dynamic range and uncertainty, a dynamic inversion control system based on time-scale and linear feedback was presented. There is no gain scheduling required in this controller, and it can adapt to the nonlinear, strong-coupled plant characteristics and large-scale changes of the environment. This controller also decreases the dependency on the aerodynamics and structure parameters in different flight conditions. In order to use different kind of actuators efficiently, a double layer control allocation method was proposed. The first layer allocates the controlling moments to the reaction control system (RCS) and aerosurface control system (ACS) depending upon the phases of flight. The second layer allocates them to the different jets in case of RCS and actuators in case of ACS (aileron, elevator and rudder) in order to generate the moments in the desired direction. It was proved by 6 degree of freedom (DOF) nonlinear simulation that the control system can accurately track guidance commands in the presence of significant aerodynamic uncertainties.