A Simulation Model of An Autonomous Helicopter

This paper describes a simulation model that has been used for controller design and stability and performance analysis of a micro X-CELL helicopter as central element of the Autonomous Scout Rotorcraft Testbed (ASRT) developed at Georgia Institute of Technology, Atlanta, USA. The general model, simple, yet comprehensive and efficient for the task at hand, consists of the following elements: helicopter model, controller, actuators, Global Positioning System (GPS) model and atmospheric turbulence model. Each module is described with emphasis on major specific characteristics. Simulation results, both for hover and forward flight conditions, are presented to illustrate the controller performance and aircraft response to specific commands. Biography M. G. Perhinschi. Mr. Perhinschi received his Dipl. Eng. degree in Aeronautical Engineering from the Polytechnic Institute, Bucharest, Romania in 1984 and the M.S. degree in Aerospace Engineering from the Georgia Institute of Technology, Atlanta, Georgia in 1994. He was with the Aircraft Enterprise in Bucharest, Romania from 1984 to 1986 as a Design Engineer and with the Institute of Fluid Mechanics and Flight Dynamics, Bucharest, Romania from 1986 to 1993 as an Aerospace Research Engineer. He is currently with the National Aerospace Research Institute, Bucharest, Romania holding the position of Senior Researcher in the Laboratory of Flight Dynamics and Control. His major interest area includes: modelling and simulation of aerospace systems, handling qualities of both fixed and rotary wing aircraft, applications of human pilot models, autonomous vehicle control, artificial intelligence techniques applied to aerospace related problems. J. V. R. Prasad. Dr. Prasad received his B.Tech and M.S. degrees in Aeronautical Engineering from the Indian Institute of Technology, Madras, India, in 1974 and 1982, respectively, and the Ph.D. degree in Aerospace Engineering from the Georgia Institute of Technology, Atlanta, Georgia in 1985. He was with the Helicopter Design Bureau of Hindustan Aeronautics Limited, Bangalore, India, as an Aeronautical Engineer from 1975 to 1980 and as a Deputy Design Engineer from 1980 to 1982. He worked as a Research Associate in the School of Aerospace Engineering at Georgia Tech from 1985 to 1987. Since then, he has been a faculty member in the Flight Mechanics and Control area in the School of Aerospace Engineering at Georgia Tech and he currently holds the rank of an Associate Professor. His research interests include flight vehicle modeling and simulation, atmospheric turbulence modeling and simulation, and nonlinear and adaptive control with applications. He served as the Chairman of the Technical Committee on Handling Qualities of the American Helicopter Society during 1994-96. He is a Senior Member of the American Institute of Aeronautics and Astronautics and a member of the American Helicopter Society. Nomenclature a GPS error dynamics parameter A system matrix of the general model * A system matrix of the intermediate helicopter model  , int A , L A auxiliary matrices 1 A lateral cyclic of the control rotor * 1 A pseudo lateral cyclic B control matrix of the general model t B control matrix of the general model with turbulence effects * B control matrix of the intermediate model B̂ , int B , L B auxiliary matrices 1 B longitudinal cyclic angle of the control rotor * 1 B pseudo longitudinal cyclic b I blade moment of inertia with respect to the hinge k GPS accuracy c k auxiliary row vector s k auxiliary row vector p k , φ k , dY k , pX k controller gains in the lateral channel q k , θ k , dX k , pX k controller gains in the longitudinal channel r k , Ψ k , i k Ψ controller gains in the yaw channel w k , Z k , Zi k controller gains in the vertical channel A M aerodynamic moment of the blade about the hinge axis p, q, r components along body axes of the body angular velocity vector R control rotor radius s Laplace variable 1 T integration step 2 T GPS update rate u, v, w components along body axes of the body center of gravity velocity vector c u control vector of the general model g g g w , v , u wind velocity vector components t u input vector in turbulence * u control vector of the intermediate model x state vector of the general model X longitudinal position * x state vector of the intermediate helicopter model Y lateral position Z vertical position β flapping angle of the control rotor c β longitudinal flapping angle of the control rotor s β lateral flapping angle of the control rotor γ Lock number θ pitch attitude angle b θ main rotor blade pitch angle c θ main rotor collective cmd θ pitch attitude command ct θ tail rotor collective ξ limited extension coefficient of the control rotor blade φ roll attitude angle cmd φ roll attitude command b ψ blade azimuth angle Ω magnitude of the shaft rotation