Differential Flatness Method Based on Pre-set Guidance and Control Subsystem Design for a Surface to Surface Flying Vehicle (TECHNICAL NOTE)


Space Research Institute, Malek Ashtar University of Technology


The purpose of this paper is to design a guidance and control system and evaluate the performance of a sample surface‑to‑surface flying object based on preset guidance with a new prospective. In this study, the main presented idea is usage of unique property of governor differential equations in order to design and develop a controlled system. Thereupon a set of system output variables have been examined by specific tests as candidate of flattened variables. It is proved that the dynamism of the studying system has a property of differential flatness. This property as a basement for observing all of the system dynamic variables could be a perfect option to remove lack of observability of nonlinear systems. According to the information gained in the procedure of flatness demonstrating, there was a similarity between the control command generating in feedback linearization and flat systems tests. This similarity led to the application of the flat systems technique for the mentioned control method. The guidance and control system suggested in this paper is able to follow a set of specific reference trajectories in order to target different ranges. This ability without recalculating controller gains could be done only by having the rate of rotate of flying object in middle phase of maneuver. To validate the proposed FBC for the studied problem, another usual control method has been investigated. For this purpose, the linear quadratic regulator as straight forward control method in optimal control field has been applied. This feature reveals full compatibility between controller block and reference trajectory generator block.