Meeting Abstract

P2.197  Thursday, Jan. 5  Tailbot – Robot with Inertial Assisted Control by an Active Tail Inspired by Lizards CHANG-SIU, E.H.*; LIBBY, T.; FULL, R.J.; TOMIZUKA, M.; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley

Lizards, discovered to pitch correct in mid-air with their tail when subjected to slippery take-off surfaces, have inspired a novel approach to stabilizing rapid locomotion in mobile terrestrial robots. To demonstrate the benefit and feasibility of this behavior we built a 177 g wheeled robot, Tailbot, with inertial sensors, a microprocessor, motor drivers, front wheel drive, and a single degree-of-freedom active tail. Since the relative inertia of the tail is dependent on the squared value of length, the mass of the tail was designed to be less than 20% of the body mass while still allowing for a one to one ratio of relative angular stroke. By estimating the body angle from the inertial sensors and utilizing both contact forces and zero net angular momentum maneuvering, Tailbot could take advantage of closed loop feedback control. Feedback produced rapid reorientation during a fall, smooth transitions between surfaces of different slopes, and stability when faced with perturbations that would overturn a tailless robot. Specifically, Tailbot could perform a 90 degree self-righting maneuver during free fall in 138 (ms) corresponding to a drop distance of approximately one body length. A perturbation, which completely overturned a tailless robot, produced a 60 degree rotation in a passive tailed robot, but resulted in only a 30 degree rotation in our feedback controlled tailed robot. Landing transitions that were not possible with a tailless robot were made feasible by properly adjusting the reference angle to the tail controller. Capabilities of Tailbot demonstrate how an active tail can improve the stability and maneuverability of terrestrial and aerial search-and-rescue vehicles and serve as a physical model to generate new hypotheses of inertial appendage control in animals.