Rapid Hover-to-Forward-Flight Transitions for a Thrust-Vectored Aircraft

Abstract

The use of differential atness for computation of a nominal trajectory for fast transition between ight modes of autonomous vehicles is investigated. Differential atness of an approximate model of the longitudinal dynamics of a thrust-vectored aircraft is used to achieve fast switching between ight modes. We conclude that steering to the trimmed state of the full model is of crucial importance for good performance. Simulations and experimental data for a thrust-vectored ight-control experiment at Caltech are provided to validate the approach.Nomenclature C x = horizontal aerodynamic coef cient C y = vertical aerodynamic coef cient C µ = rotational aerodynamic coef cient N c = mean aerodynamic chord, m D = aerodynamic drag, N J = inertia, kg ¢ m 2 L = aerodynamic lift, N M = aerodynamic moment, Nm m g = gravitational mass, kg m x = inertial mass in x direction, kg m z = inertial mass in z direction, kg Q = pitch rate, rad/s r = distance from center of mass to point where thrust acts, m S = wing surface, m 2 T 1 = forward thrust, N T 2 = downward thrust, N U = forward body velocity, m/s V = absolute velocity, m/s W = downward body velocity, m/s x = spatial horizontal coordinate, m/s, or state of a system x f = x coordinate of the center of oscillation z = spatial vertical coordinate, m/s, or at output z f = z coordinate of the center of oscillation ® = angle of attack, rad ± = elevator, deg 2 = angle of aircraft with the vertical: µ ¡ ¼=2, rad µ = pitch angle, rad ½ = density, kg/m 3

Online Control Customization via Optimization‐Based Control

“…, u (p) ) such that all feasible solutions of the underdetermined differential equation (1) can be written as Differentially flat systems were originally studied by Fliess et al [9]. See [24] for a description of the role of flatness in control of mechanical systems and [33] for more information on flatness applied to flight control systems.…”

“…In this way, we reduce the problem of generating a feasible trajectory for the system to a classical algebraic problem in interpolation. Similarly, problems in trajectory generation can also be converted to problems involving curves z(·) and algebraic methods can be used to provide real-time solutions [33,34].…”

High Confidence Reconfigurable Distributed Control

“…In Primbs et al [26], aspects of a stability-guaranteeing, global control Lyapunov function were used, via state and control constraints, to develop a stabilizing receding horizon scheme. Many of the nice characteristics of the CLF controller together with better cost performance were realized.…”

Longitudinal dynamics, optimization and control of aircraft transition maneuver using aerodynamic vectoring

“…The seminal work for the transition phenomena on UAV platforms can be attributed to Nieuwstadt and Murray [5]. During the study [14] In recent studies, Green and Oh [22][23][24] The utilization of flaps and slats is shown to improve the transition performance by reducing altitude gain but with penalty on the transition time During the wind-tunnel testing by Moschetta et.…”

“…The aerodynamic properties discussed up to this point are steady or quasisteady in nature and has been used for evaluating agile maneuvers in most investigations [5,29,33,43]. In a quasi-steady approach, any change in angle of attack of the aircraft results in instantaneous change in aerodynamic properties.…”