Wing Transmission for a Micromechanical Flying Insect

Flapping wings provide unmatched maneuverability for flying micro-robots. Recent advances in modelling insect aerodynamics show that adequate wing rotation at the end of the stroke is essential for generating adequate flight forces. We developed a thorax structure using four bar frames combined with an extensible fan-fold wing to provide adequate wing stroke and rotation. Flow measurements on a scale model of the beating wing show promising aerodynamics. Calculations using a simple resonant mechanical circuit model show that piezoelectric actuators can generate suificleat power, force and stroke to drive the wings at 150 Hz. 1 I n t r o d u c t i o n Flapping flight for micro-robots is not only an intriguing mode of locomotion, but provides maneuverability not obtainable with fixed or rotary wing aircraft. Insects can fly with a payload equal to their body mass, and have peak accelerations approaching lOm/s 2 [May 1991]. Although they require relatively still air, flying micro-robots can fly over terrain which would he impassable for a legged micro-robot. Following the initial vision of Flynn [1987], pioneering work in micro-robotic flight was started by Shimoyama [Shimoyama et al 1993; Kubo et al 1994; Miki and Shimoyama 1998] and more recently, milli-robotic flapping flight by [Cox, Garcia, and Goldfarb, 1998]. This paper considers the kinematic and power requirements for a micro-robotic flying device using beating wings, and presents an initial design of a thorax for the device. As shown in Figure 1, we will be using flexural 4 bar elements to provide sufficient wing stroke, and a compliant wing which can deform to provide rotation. A summary of the MFI component dimensions is given in Table 1. Further work is *This work was funded by O N R M U R I N00014-98-1-0671, O N R D U R I P N00014-99-1-0720 and D A R P A . 0 -7803 -5886 -4 /00 /$ 10 .00© 2000 IEEE 15 t . of In t eg ra t ive Bio logy f Cal i forn ia 94720-1770 Figure 1: Conceptual drawing of micromechanical flying insect. MFI c o m p o n e n t size to ta l m a s s 4-bar f r ames l inks 5,5,4, 0.7 m m 20 m g (2 per wing) 1 m m box b e a m base f rame ( m m ) 10 × 4 × 1 m m 8 m g piezo a c t u a t o r 0.25 × 5 x 0.2 m E 15 m g (2 per f rame) ( total 8 ac tua to r s ) wings 5 × l0 × .01 m m 3 m g (polyester) to ta l s t r u c t u r e 43 m g Table 1: Components of final size MFI. Structure will be made from 10~m thick 302 stainless. required with models and prototypes before solving the critical issues of control, sensing, or power supply. As a design target for the micromechanical flying insect (MFI), we are using the blowfly Calliphora, which has a mass of 100 mg, wing length of 11 mm, wing beat frequency of 150 Hz, and actuator power of about 8 mW. At this size scale, the current best understanding of non-steady state aerodynamics comes from experimental observations of real insects and kinematically similar mockups [Ellington et al 1996; Dickinson and GStz 1996].