Dynamic Modelling and Analysis of a Vectored Thrust Aerial Vehicle Wei Yuan, Hiranya Jayakody and Jay Katupitiya School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Australia {w.yuan@unsw,j.katupitiya@unsw,hiranya.jayakody@student}.unsw.edu.au Abstract This paper presents the dynamic modelling of a Vectored Thrust Aerial Vehicle (VTAV) powered by ducted fans, some of which can be vectored. First, a comprehensive nonlin- ear dynamic model of the system is devel- oped. The model is then linearized around the hover equilibrium and the characteristics of the linearized model is analyzed. The per- formance of the linearized model is compared with the nonlinear model for various test con- ditions in order to identify the important pa- rameters that need to be taken into consid- eration in developing a robust controller for the VTAV. 1 Introduction Research in to Micro Aerial Vehicles (MAV) has in- creased significantly in the past several decades due to their applicability in various civil and military appli- cations. Features such as Vertical Take Off and Land- ing (VTOL) capability has further enhanced the use of MAVs in congested environments where the vehicle has little space for take-off and landing[Marconi et al., 2011]. MAVs are developed based on open propellers [Liu et al., 2009] such as coaxial helicopters and quad ro- tors, as well as ducted fanned systems [Naldi et al., 2010]. Among the two categories ducted fan based aerial vehicles have many advantages that deserve a greater attention than has been to date. Ducted fans provide safe operation in cluttered environments where the objects in the proximity of the vehicle are pro- tected from the propeller and vice versa. Further, the ducted fanned systems exhibit better overall efficiency at low speeds, due to the reduction of blade tip losses as well as predefined uniform cross section. Other ad- vantages unique to the design presented in this paper are discussed below. The majority of the research aimed at ducted fanned systems are based on single ducted fan platforms such as iStar9, HoverEye, AROD, GTSpy with a fuse- lage and control surfaces mounted beneath the ducted Figure 1: Vectored Thrust Aerial Vehicle (VTAV) propeller [Johnson and Turbe, 2006] [Pflimlin et al., 2010]. However these types of single ducted fan sys- tems show large pitch and roll movements during for- ward flight [Omar et al., 2008] which is highly undesir- able in applications like terrain mapping using a sen- sor payload. Furthermore, these types of vehicles are unable to carry a large payload due to their design lim- itations. Quad-rotor platforms on the other hand pro- vides payload carrying capacity yet need to undergo roll and pitch movements for forward and sideways flight [Bai et al., 2011]. Designs similar to the aerial vehicle discussed in this paper which includes multi- ple ducted fans with vectoring are rare. Due to its vectoring capability, this MAV is known as a Vectored Thrust Aerial Vehicle (VTAV) [Kumon et al., 2010]. The VTAV overcomes the above mentioned disadvan- tages of the existing MAVs through its unique design. The VTAV which has a triangular shape consists of three ducted fans as shown in Figure 1. The rear two ducted fans can be vectored or turned about an axis common to both ducted fans. The independent vec- toring of these two fans allows the yaw motion and forward flight with minimal or no pitch movement. As will be seen, the dynamic model demonstrates unsta- ble equilibrium and is significantly simpler than the dynamic model of a helicopter. The fact that the sys- tem is in unstable equilibrium also allows us to develop control systems that will provide greater maneuver- ability than would have been possible with quad-rotor Proceedings of Australasian Conference on Robotics and Automation, 3-5 Dec 2012, Victoria University of Wellington, New Zealand.