Development of a Gun-Launched Rotary-Wing Micro Air Vehicle

Abstract

This paper describes the development of a compact and re-configurable rotary-wing micro air vehicle (MAV) that is capable of sustained hover and could potentially be launched from a 40 mm grenade launcher in the future. Launching the vehicle as a projectile up to the point of operation could significantly improve the mission range for these energy-constrained platforms. The MAV design used coaxial rotors with forldable blades, a thrust-vectoring mechanism for pitch and roll control, and a strict constraint on the outer diameter, which was relaxed to 52 mm for this study. Yaw control was accomplished by using a specialized counter-rotating motor that is composed of two independently controlled motors. Passive unfolding of the coaxial rotor blades utilizing centrifugal force was demonstrated. The vehicle attitude was stabilized in hover using a closed-loop proportional-derivative controller implemented on a 1.7 gram custom autopilot. Through systematic trimming and tuning of the feedback gains, the vehicle was able to achieve stable hover. When the vehicle was subjected to large impulsive itch and roll perturbations, the feedback controller was able to successfully reject the disturbance and retgurn the vehicle to a stable hover within a second. In parallel, an analogue of the flying vehicle or a "dummy" was built and launched using a pneumatic canon to understand the dynamics of the vehicle during the projectile phase without risking the actual flying vehicle. The launch demonstrated that with the right center of gravity location, the present vehicle configuration could be stable during the projectile flight even without fins.