309 - IAV2004 - PREPRINTS 5th IFAC/EURON Symposium on...

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MODEL PREDICTIVE CONTROL AND DYNAMIC INVERSION FOR UNMANNED AERIAL VEHICLE Z. Cheng*, D. Necsulescu*, B. Kim** * Department of Mechanical Engineering, University of Ottawa, Canada ** DRDC, Ottawa, Canada Abstract: Unmanned aerial vehicles represent a particular class of autonomous vehicles that have to maintain stability in difficult flight conditions and achieve missions under autonomous control. This paper presents a Model Predictive Control applied to a linearized system using Dynamic Inversion. Simulation results obtained using a nonlinear model of the unmanned aerial vehicle are presented. Copyright © 2002 IFAC Keywords: Control, Navigation, Linearization, Model Predictive Control, Autonomous Vehicles 1. INTRODUCTION Unmanned Aerial Vehicles (UAVs) are aircrafts that are stabilizable using feedback controllers and that are supposed to navigate as autonomously as possible. Model Predictive Control (MPC) is an interesting solution for UAV control, but requires a linearized system at this time, given that nonlinear MPC is still in an early development stage. In this paper, MPC is applied to a linearized UAV using a dynamic inversion. Simulation results obtained using a nonlinear UAV model are presented and analysed to verify suitability for UAV autonomous control. 2. UAV NONLINEAR MODEL The UAV six-degree-freedom nonlinear models of rigid body are described by force equations, moment equations and kinematic equations in various frames of references (Stevens and Lewis, 1992; McLean, 1990 and Nelson, 1998) and AeroSim blockset user guide (http://www.u-dynamics.com/aerosim/). For a set of frames of reference considered convenient for this paper, the UAV model is given by Force equations in Wind Frame 1 2 3 cos 0 sin 1 T T T w TT w T T T T Fg d V y r mV V V q Fl V V V αβ β α T g ⎧⎫ ⎡⎤ ⎪⎪ ⎢⎥ =+ + + ⎨⎬ −− ⎣⎦ ⎩⎭ (1) where cos cos sin sin cos cos sin cos sin sin sin cos w w w pp q r qp qr rp r ββ αα ++ ⎡⎤⎡ ⎢⎥⎢ =− + −+ ⎣⎦⎣ (2) and ( ) () 1 2 3 cos cos sin sin sin cos sin cos cos cos cos sin sin cos sin cos sin sin cos cos sin sin cos cos cos gg βθ φ θ φθ αθ −++ + (3) where are aerodynamic forces which are expressed by the dimensionless aerodynamic coefficients , dy l 2 0 2 0 2 2 0 1 2 1 22 1 f ea r a r f e LL Td d f d e d a d r pr Ty y a y r y y T q Tll l f l e l l T CC dV S C C CCC eAR b yV S CCC C p C r V c lV S C C a C C q V δ δδ ρ π ρβ ρδ =++ + + + + + + ⎛⎞ + + + + ⎜⎟ ⎝⎠ (4) Moment equations in the body frame 12 3 4 56 7 82 49 p cr c p q cL cN qc p rcp r cM rc p c r q c L c N =− − + =− ++ (5) where the inertial coefficients are expressed as follows: 2 34 2 78 2 9 1 where xyz x z yz zx z xz z x z yy xy xx z y x xz x z III I II cc I I I IIII I I cI == ΓΓ Γ Γ I I = After neglecting the cross-coupling in inertial coefficients, the simplified moment equations are written as IAV2004 - PREPRINTS
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309 - IAV2004 - PREPRINTS 5th IFAC/EURON Symposium on...

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