Active Tail Configurations for Enhanced Body Reorientation Performance.

During dynamic locomotion, animals employ tails to help control the orientation of their bodies. This type of control is pervasive throughout locomotion strategies. Roboticists endeavor to close the gap between robots and their biological counterparts by developing various active tails. This work explores these active tails and establishes a design strategy to enhance reorientation performances. A dynamic model to describe the transmitted torques at the body from the single-axis active tail is suggested. The design parameters, which define the transmitted torques, are analyzed through the dynamic model to understand their contributions. The effects of aerodynamics on the active tail's performance are also explored. The active tails are categorized according to inertial tail designs (unbalanced distal mass or mass-balanced about a rotating point), aerodynamic configurations (inertial, aerodynamic, aerodynamic with external airflow), and operating strategies (partial oscillation, symmetric oscillation, asymmetric-oscillation or full rotations). The reorientation performance of 24 possible active tail combinations is explored and design strategies to select the proper combinations according to the target system's conditions are provided. This work can help in guiding the advanced active tail designs for future agile mobile robots.