Dynamics and Control of a Heavy Lift Airship Hovering in a Turbulent Cross Wind

Abstract

Dynamics and control characteristics of a quadrotor heavy lift airship with a sling load are determined while the vehicle is hovering in a turbulent cross wind. Results are presented which show the significance of the dynamic coupling between the vehicle and payload in their response to wind disturbances and control inputs. Typical characteristics of a closed-loop control system and its ability to limit the excursions of the vehicle and payload during loading or unloading are also examined.//* Nomenclature = system dynamics matrices = system control matrix = feedback gain matrix -feedback gain proportional to vehicle velocity = feedback gain proportional to vehicle displacement = feedback gain proportional to payload velocity = feedback gain proportional to payload displacement = acceleration due to gravity, ft/s 2 = sling load aerodynamic drag constant = scale of turbulence, ft = length of the payload suspension cable, ft = mass of the vehicle, slug = mass of the payload, slug = static lift, Ib = disturbance matrix = control variable = mean wind velocity, ft/s = total velocity of the sling load, ft/s = lateral velocity of the vehicle along its y body axis, ft/s = turbulence velocity, ft/s = lateral velocity of the payload relative to the vehicle along the y body axis of the vehicle, ft/s = gross weight of the vehicle, Ib = gross weight of the sling load, Ib = state vector = derivative of the state vector with respect to time = lateral control force derivative, Ib/rad = vehicle lateral aerodynamic force derivative with respect to its lateral velocity, Ib/ft/s = vehicle lateral aerodynamic force derivative with respect to its lateral acceleration, slug = lateral displacement of the vehicle along its y body axis, ft = lateral displacement of the payload relative to the vehicle along the y body axis of the vehicle, ft = lateral displacement of the payload relative to the ground, ft = prefix used for small perturbation = damping ratio =root mean square value of fluctuating wind velocity in the y direction of vehicle body axes, ft/s = power spectrum of wind turbulence, ft 3 /s 2 = circular frequency, rad/s = natural frequency, rad/s = spatial frequency (= a;/ V), rad/ft

Positioning control for an unmanned airship using sliding mode control based on fuzzy approximation

“…where 4,5,6). By adopting the abovementioned sliding surface and approaching law, the control inputs are designed as follows…”

“…Schmidt proposed a controller followed a conventional loop-shaping approach compatible with the characteristic dynamics of a large high-altitude airship. 5 Nagabhushan and Tomlinson 6 presented a feedback control approach for a quad-rotor heavy lift airship with a sling load, and investigated the dynamics and control characteristics of the airship while it is hovering. Control approaches proposed by Schmidt 5 and Nagabhushan and Tomlinson 6 have limitations because they were developed based on the linear model, neglecting nonlinearity and coupling effects between the longitudinal and lateral motion.…”

“…5 Nagabhushan and Tomlinson 6 presented a feedback control approach for a quad-rotor heavy lift airship with a sling load, and investigated the dynamics and control characteristics of the airship while it is hovering. Control approaches proposed by Schmidt 5 and Nagabhushan and Tomlinson 6 have limitations because they were developed based on the linear model, neglecting nonlinearity and coupling effects between the longitudinal and lateral motion. Azinheira and Moutinho 7 and Hygounenc and Soueres 8 developed the airship controller based on the backstepping technique, which allows considering the kinematic and dynamic requirement separately.…”

Autonomous Flight in Hover and Near-Hover for Thrust-Controlled Unmanned Airships

“…Tackling this issue requires the careful design of automatic flight controllers, which on unmanned airships act towards artificial stabilization and guidance as well. Much literature has been devoted in relatively recent times to the application of diverse control techniques to forward flight and terminal maneuvers of airships featuring aerodynamic control [17][18][19][20][21] or to the industrially adopted solution of thrust vector control (TVC) [22,23]. Some attention has also been devoted to station keeping tasks in a steady wind condition for a few specific configurations [24][25][26].…”