Funnel Flight Controller for a TDR 6-DoF Simulation Model

Abstract

A Throttleable Ducted Rocket (TDR) is a ramjet-type engine using a solid propellant for which the fuel mass flow rate can be controlled. Since the propellant has an oxygen deficient formulation, fuel rich combustion products are produced within the gas generator which are exhausted into the ram combustor and are afterburned with air. Modeling is an extremely important tool for proper TDR design. For the TDR, this model has to represent the internal aerodynamics – including the two combustion processes within the gas generator and the ram combustor – accurately. The simulation of in-flight performance has been an important area throughout the history of missile development. The use of formal methods for analysis and predictability is essential, since it is impractical to cover all of the operational regime of an air-breathing propulsion system by ground tests and flight tests of the complete missile are extremely expensive. This paper investigates the trajectory prediction for a guided and thrust controlled ramjet missile. In this paper, a trajectory simulation model using a 6-DoF model was developed and applied for a typical TDR. A detailed description of the 6-DoF method is provided. An effort has been made to take into account the aerodynamic, gravitational and inertial coupling dynamics. This paper starts with a description of the general design of a TDR and the motor model. A brief introduction to the motor control algorithms is then provided. This is followed by a description of the mathematical 6-DoF trajectory simulation model including a flight controller – a so-called 4-dimensional performance funnel. For all models, a funnel controller method is used as an automatic optimization and control tool. In this paper, it is shown how the 6-DoF model of the TDR is used in a simulation for a military enemy trajectory track.