Design concept for stabilising and controlling rotary wing micro air vehicles in gusts

Rotary Wing Micro Air Vehicles (RW-MAV) hold great potential in the surveillance and the reconnaissance fields as they are capable of vertical take off and landing, hover and ‘perch and stare’. However, their small size and light weight render them more sensitive to gusts, such as in an urban canyon, making them very difficult to control in such conditions. This study presents the results of a novel design concept that focuses on increasing the stability of a RW-MAV without the use of complex sensors or control laws. The results show that by using the proposed aerodynamic design (inclusion of stabilising fin) together with changing the centre of mass for longitudinal control, a micro coaxial contra-rotating helicopter weighing about 200 grams can have considerably increased stability and become easily controlled in gusty conditions. Simulation and flight test data of a small radio controlled (RC) RWMAV built at the University of Bristol are presented for endorsement of the theory. This paper first describes the difficulties in flying a RW-MAV based on flight tests of a commercial off the shelf RC indoor micro helicopter. The proposed design concept is then explained and the effects of implementing this concept on the RC indoor micro helicopter are presented. The preliminary results show that the micro helicopter can be flown in wind conditions gusting up to 10 mph. The paper then presents the simulation analysis conducted to further understand the proposed design concept and to utilise it in optimising the RW-MAV design so that it can be flown in higher gust conditions.