DOI: 10.5061/dryad.hqbzkh1p3
title: Kinematic data and mathematical modeling of sea star locomotion

description: It is unclear how animals with radial symmetry control locomotion without
 a brain. Using a combination of experiments, mathematical modeling, and
 robotics, we tested the extent to which this control emerges in sea stars
 from the local control of their hundreds of feet and their mechanical
 interactions with the body. We discovered that these animals (Protoreaster
 nodosus) compensate for an experimental increase in their submerged weight
 by recruiting more feet that synchronize in the power stroke of the
 locomotor cycle. Mathematical modeling replicated this response to loading
 in the absence of nervous communication and demonstrated how the body
 weight serves as a regulator of recruitment. We built a robotic sea star
 with an array of independently-controlled actuators that were also
 recruited in greater numbers under higher loads due to their collective
 mechanics. These findings demonstrate that an array of actuators in
 biological and robotic systems are capable of cooperative transport with
 dynamic adjustments to loading. This form of distributed control contrasts
 the conventional view of animal locomotion as governed by the central
 nervous system and offers inspiration for the design of engineered devices
 with arrays of actuators.
description: The dataset includes code necessary to acquire and analyze the
 kinematics of sea -star locomotion. The ressulting data files are
 included. In addition, we have included the code to mathematically model
 the mechanics of sea-star locomotion.
description: # Kinematic data and mathematical modeling of sea star locomotion
 MATLAB data and code for
 kinematic analysis and mathematical modeling. Here is a catalog of
 individual items in the repository: ## 1D model Matlab code for performing
 simulations of a one-dimensional mathematical model. The file spring.m
 performs the numerical simulation and the remaining functions allow for
 plotting and analyzing the results. ## 2D model Matlab code for performing
 simulations of the 2D model of the mechanics of a sea star. The spring.m
 function performs an individual simulation and runBatch.m runs that
 function in the variety of ways detailed in the manuscript. The remaining
 functions allow for analyzing and visualizing the results. ##
 Animal\_kinematics\_code Includes Matlab code for acquiring and analyzing
 kinematics. Specifically, we used
 [DeepLabCut](http://www.mackenziemathislab.org/deeplabcut) to collect
 kinematics of locomotion of sea stars from a side view. Automated tracking
 in matlab was used to measure whole-body motion using thresholding. The
 manual tracking was performed in matlab to measure the motion of
 individual tube feet. ## Animal\_kinematics\_data Includes the data files
 for side-view kinematics (acquired with DeepLabCut) and the individual
 foot tracking. The results of all experiments are summarized in
 Weights_experiments.xlsx. Inappropriate or unnecessary values entered as
 "null". The tube-foot kinematics are stored within the
 'F' structure, save in 'footData.mat', with units of
 meters and seconds. The 'ftL' field in the 'F'
 structure stores the kinematics with respect to the stroke plane of the
 power stroke of each foot. All coordinates contained within
 'side-view data' are in pixels, with the spatial calibration
 constant for each in Weights_experiments.xlsx. ##
 Robotics\_experiments.xlsx Includes all measurements for the robotics
 experiments. A lack of notes recorded as "null".