Wing Warping Control of Flexible Membrane Wing Under Gusty Conditions

Flying in gusty winds with a mini-UAV has always been a challenge as the moment of inertia and weight of the vehicle is typically low. In order to improve the flight quality of the mini-UAV, a flexible membrane wing has been fabricated with added desirable features. This wing is able to dampen the high-frequency gusts via the adaptive washout and also fold along the fuselage for quick storage and deployment. However, the actuation of the wing for roll control is difficult if these two properties are not to be compromised. A novel method of wing warping for roll control with a tendon-sheath has been investigated. The nonlinearities of the tendon-sheath mechanism require extra control strategies for accurate wing warping control. The nonlinear characteristics of the wing warping via tendon-sheath has been examined, and a suitable model is designed and implemented in a controller to compensate for the nonlinearity. The performance and robustness of the system is subsequently tested in gusty conditioned wind tunnel with satisfactory results.