Bat Bot (B2), an Articulated-Winged Bat Robot
Alireza Ramezani∗
Xichen Shi†
Soon-Jo Chung∗
Seth Hutchinson∗
Abstract
In recent years, few works [1] have applied rigorous mathematics to design sophisticated flapping motions similar to bats. However, the morphological and kinematic features of flying vertebrates are still the underappreciated
aspects of locomotor control designs for Unmanned Aerial Vehicles (UAVs).
In this work we introduce Bat Bot, in short B2, shown in Fig. 1-(a), which is a biologically inspired articulatedwinged micro aerial vehicle that is capable of mimicking a variety of motions and maneuvers, including but not
limited to steady level flight without a conventional tail, rapid turning, inverse perching and hovering. To achieve
such goals, biologic bats were examined to determine certain key morphological features of B2. Because of the
inefficiency of electric actuators compared to the biologic muscles of these mammals, certain compromises have
to be made to enable B2 for self-sustained flight.
(a) B2
(b)
(c)
Fig. 1: (a) B2, articulated-winged bat robot. (b,c) The wing articulation in bat, [2].
For a comparable performance to real bats, B2 is designed to have a wingspan of 40 cm, and a gross weight
of 60 ± 20 g, which approximately will resemble Rousettus aegyptiacus, [3]. Although real bats are reported to
have more than 35 degrees of freedom (DoF) on each wing, B2 will incorporate 3-DoF – flapping, feathering,
and extension – on each forelimb, and 2-DoF – pitch and lead-lag – on each hindlimb. Overall mechanism with
5-DoF per wing can flap at approximately 10 Hz and can modulate the wingspan, sweep\ pitch angle, and wing
cambering. Turning to the actuators, B2 has a synchronous flapping mechanism which is driven by a 5 gr brushless motor and a 3D-printed planetary gear box with a 1:36 gear reduction ratio. Two micro servo actuators are
allocated for each humerus for the feathering and extension motions. Additionally two servo actuators modulate
the angle of each hindlimbs dorsoventrally and mediolatterally. B2 is a self-sustaining platform meaning it has a
computing unit in order to evaluate the control flight algorithm. In addition, the robot has an inertial measurement
unit (IMU) to evaluate the quaternions and has several hall effect – magnetic field – encoders to measure the
wing flapping angles.
R EFERENCES
[1] Soon-Jo Chung and Michael Dorothy. Neurobiologically inspired control of engineered flapping flight. Journal of guidance, control,
and dynamics, 33(2):440–453, 2010.
[2] Xiaodong Tian, Jose Iriarte-Diaz, Kevin Middleton, Ricardo Galvao, Emily Israeli, Abigail Roemer, Allyce Sullivan, Arnold Song,
Sharon Swartz, and Kenneth Breuer. Direct measurements of the kinematics and dynamics of bat flight. Bioinspiration & Biomimetics,
1(4):S10, 2006.
[3] Ulla M Norberg. Functional osteology and myology of the wing of the dog-faced bat rousettus aegyptiacus (´e. geoffroy)(mammalia,
chiroptera). Zeitschrift f¨ur Morphologie der Tiere, 73(1):1–44, 1972.
∗ Coordinated
† Aerospace
Science Laboratory, University of Illinois,Urbana, IL, 61801
Engineering Department, University of Illinois,Urbana, IL, 61801