Trajectory tracking in the sagittal plane: Decoupled lift/thrust control via tunable impedance approach in flapping-wing MAVs

Flapping-wing micro-aerial vehicles (MAVs) are a relatively new field of research in the robotics community. Inspired by insects, their small size and unique means of force production present many challenges, from morphological construction and power supply to control methodology. Over the past couple of decades, investigating the aeromechanics of insect flight and development of prototypes have been a major focus of most researchers in this field. Those works concentrating on force manipulation and motion control often rely on modifying the properties of wing-beat profile. However, such changes affect both lift and thrust simultaneously, making it very difficult to control these forces independently. The tunable impedance (TI) approach is an alternate method of force manipulation that modifies mechanical impedance properties of the wings rather than their stroke characteristics. In this work, we show how TI can be used to achieve decoupled lift/thrust control. A motion controller developed based on this feature enables a fly-sized model to track given trajectories in the sagittal plane. Results of simulated experiments with various types of trajectories demonstrate a high degree of precision and maneuverability.