Six-DoF UAV simulation using wind tunnel test data and its cruise mode autopilot design

In this paper an autopilot system is designed for cruise mode of a fixed wing unmanned aerial vehicle (UAV). The biggest challenge is to maneuver UAV at lower altitudes while overcoming strong coupling between longitudinal and lateral mode. The six-DoF simulation model of the UAV plant under consideration is a non-linear one, to control it for cruise mode it is trimmed at cruise conditions for decoupling of plant model. The control design is divided into two phase, in first phase PID controllers are designed for individual parameter hold related to the cruise flight envelope. In the next phase a decoupled single control with the capabilities of controlling all the parameters for cruise mode is designed. Parallel control loop structure are designed to generate the throttle and elevator control command which indeed control forward speed and altitude of the UAV during cruise. This paper will thus discuss the steps by step procedures in setting up the non-linear flight model/plant, trimming method, flight dynamics, designing control laws and plant validation using simulation software. The mathematical modelling and simulation of UAV aerodynamic wind tunnel test data are adopted from Indian Institute of Science, Bangalore.