Insect and bird size drones – micro air vehicles (MAV) that can perform autonomous flight in natural and man-made environment and hence suitable for environmental monitoring, surveillance, and assessment of hostile situations are now an active and well-integrated research area. Biological flapping-flight system design that has been validated through a long period of natural selection offers an alternative paradigm that can be scaled down in size, but normally brings lowspeed aerodynamics and flight control challenges in achieving autonomous flight. Thus mimetics in bioinspired flight systems is expected to be capable of providing with novel mechanisms and breakthrough technologies to dominate the future of MAVs. Flying insects that power and control flight by flapping wings perform excellent flight stability and manoeuvrability while steering and manoeuvring by rapidly and continuously varying their wing kinematics. Flapping wing propulsion, inspired by insects, birds and bats, possesses potential of high lift-generating capability under lowspeed flight conditions and may provide an innovative solution to the dilemma of small autonomous MAVs. In this study, with a specific focus on robustness strategies and intelligence in insect and bird flights in terms of morphology, dynamics and flight control, we present the state of the art of flying biomechanics in terms of flapping wing aerodynamics, flexible wing and wing-hinge dynamics, passive and active mechanisms in stabilization and control, as well as flapping flight in unsteady environments. We further highlight recent advances in biomimetics of insect-inspired flapping MAVs in concern with wing design and fabrication.
A new designing concept to realize multifunctional structural material systems without using sophisticated functional
materials was proposed and demonstrated in this paper. The concept can be explained as follow: There exist a couple of
competitive structural materials which normally compete with each other because of their similar and high mechanical
properties, and they tend to have another property which is different from each other or opposite among them. So if they
are combined together to make a composite, the similar property, normally high mechanical property, can be maintained,
and the other dissimilar property conflicts with each other, which will successfully generate a functional property
without using any sophisticated functional materials. According to this concept, two examples, that is, a CFRP/Al active
laminate and a Ti fiber/Al multifunctional composite were made and it was successfully demonstrated.
This paper describes development of high performance CFRP/metal active laminates and demonstrations of them in complicated forms. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature. The aluminum type active laminate was made into complicated forms, that is, a hatch, a stack, a coil and a lift types, and their actuation performances were successfully demonstrated.