DOI: 10.5061/dryad.9s4mw6mm4
title: Hummingbirds rapidly respond to the removal of visible light and control a sequence of rate-commanded escape maneuvers in milliseconds

description: Hummingbirds routinely execute a variety of stunning aerobatic feats,
 which continue to challenge current notions of aerial agility and
 controlled stability in biological systems. Indeed, the control of these
 amazing maneuvers is not well understood. Here we examined how
 hummingbirds control a sequence of maneuvers within milliseconds and
 tested whether and when they use vision during this rapid process. We
 repeatedly elicited escape flights in Calliope hummingbirds and removed
 visible light during each maneuver at various instants and quantified
 their flight kinematics and responses. We show that the escape maneuvers
 were composed of rapidly-controlled sequential modules including evasion,
 reorientation, nose-down dive, forward flight, and nose-up to hover. The
 hummingbirds did not respond to the light removal during evasion and
 reorientation until a critical light-removal time; afterward, they showed
 two categories of luminance-based responses that rapidly altered
 maneuvering modules to terminate the escape. We also show that hummingbird
 maneuvers were rate-commanded and required no active braking, i.e., their
 body angular velocities were proportional to the change of wing motion
 patterns, a trait that likely alleviates the computational demand on
 flight control. This work uncovers key traits of hummingbird agility,
 which can also inform and inspire designs for next-generation agile aerial
 systems.
description: # Hummingbirds rapidly respond to the removal of visible light and control
 a sequence of rate-commanded escape maneuvers in milliseconds ##
 Description of the Data and file structure The mat file contains data from
 two birds used in the experiments (bird_1 and bird_2) --- **tSH:**
 contains the data on the relationship between light removal time instance
 and time to stop and hover. * logitRegg: logistic regression optimized
 parameters and critical light removal time instance. * linearModel: Linear
 fit model for light removal time instance and time to stop and hover for
 Category II and Category III demonstrations. * data: Raw data of light
 removal time instance and time to stop and hover.  [time in milliseconds]
 --- **hoverData:** Wing kinematics data during hovering before the start
 of escape maneuvers * LWstr: Left-wing stroke angle [degree] * LWdev:
 Left-wing deviation angle [degree] * LWstr: Left-wing pitch angle [degree]
 * RWstr: Right-wing stroke angle [degree] * RWdev: Right-wing deviation
 angle [degree] * RWstr: Right-wing pitch angle [degree] * t: normalized
 time [0,1] for wing beat cycle [time in seconds] --- **kinematics:**
 Complete bird kinematics during escape maneuver (Forward: Bird pitch down
 to forward flight, Pd-F after reorientation, Category I and III; Stopping:
 Bird pitch up to Hover, Pu-H after reorientation) * Wing: wing kinematic
 is in format (Stroke, Deviation, Pitch) [degree] * Body: variable
 represent a vector in the global frame while variable_b represent a vector
 in the body fixed frame [velocity in m/s and angular velocity in deg/s] *
 Beak: The angular velocity of the beak [degree/sec] * time: time stamps
 for each trials [seconds] * type: weather the trial is a case of Forward
 or stopping * Point: Raw 3D digitized data [m]  --- **intendedTraj:**
 Kinematic data for estimated intended trajectory during escape maneuver *
 Y_mean & Y_sd: mean and stand deviation for the estimated trajectory
 the variables in Y are defined in the description * Time_Align: The time
 stamps for the aligned kinematics [ms] * SegUp: The index of end of
 upstroke in the "Time_Align" variable * SegDown: The index of
 end of downstroke in the "Time_Align" variable * Id: The raw
 aligned and unalign kinematic data (the index of each variable is
 mentioned in "Description" variable) * Group:
 'Align_All_Cases' means both data from all the trials were used
 for the alignment * GroupName: 'All_Cases' = All the trials ---
 **WMP_analysis**: Data for Wing Motion Primitive analysis *
 wingBeatDistFromHover: Statistical distance of each wing beat from hover
 wing beat estimate [probabilistic distance] * WMPs: Wing motion primitives
 for hover(H), evasion(PuB) and reorientation(R) * wingBeatWMP: WMP
 magnitude in each wingbeat of all the demonstrations [degree] * crossCorr:
 Cross-correlation analysis data for pitching and rolling  * AngRateFit:
 Data for the relationship between WMP magnitude and angular rates
 [degree/sec]