MMEAW: Modelling the MEchanics of Animal Whiskers

Lead Research Organisation: London South Bank University
Department Name: School of Engineering

Abstract

MMEAW is a multidisciplinary project, lying at the interface between structural engineering, robotics and comparative animal physiology. It aims to extend our understanding and knowledge of how whiskers are adapted to their function and apply that understanding to applications in engineering. MMEAW builds on previous research in this field, for example the EPSRC funded Whiskerbot project (EPSRC ref: GR/S19639/01).
The aims of MMEAW are as follows:
1) Understanding how animals exploit a range of whisker morphological parameters such as taper, curvature, twist, stiffness, anisotropy and weight, to their advantage.
2) Determining critical values of taper, twist, curvature and relationships between them e.g., ratio of weight to length (curliness), which lead to qualitative change in vibrissae mechanics. Thereby identify criteria for optimal performance.
3) Establishing a rational scheme for classifying vibrissae.
MMEAW involves two key activities. First, by taking measurements of the shape and form of animal whiskers, it will build a data base of detailed information on whisker morphologies. Working with museums, we shall gather data on a range of species - from small rodents, to large mammals and to birds. The information we are interested in includes details of the length, curvature, taper, weight, tortuosity (i.e., out of plane curvature), and cross sectional properties, such as shape, diameter and stiffness. We also want to know details of how and where each whisker connects to the animal's face, including the angle and orientation of the whisker. All that information will be stored in a data base. Since no such data base exists anywhere, it will be made available to museums internationally, where it can be aggrandized. The process of gathering data on vibrissae will last one year.
The second major activity involves the formulation of mathematical models, using the data gathered on vibrissae shape and form, and applying mechanics principles to analyse what happens to a whisker when its tip is disturbed e.g., when it brushes against different surfaces, is pressed in by a force, passes through a liquid (otters and seals) and undergoes the 'whisking motions' observed in some species (rats). MMEAW will use advanced modelling methods, based on the Cosserat Theory of rods, i.e., a rigorous mathematical theory of long slender structures. That approach will enable MMEAW to model the effects of different curvatures, tapers, tortuosity etc., within a unified and rational scheme, one that provides detailed information on the loads transmitted from the tip of the whisker to the base. The modelling and analysis will be complemented by field work (observations of animals) carried out by a member of the team with extensive specialist experience. Indeed, MMEAW involves the collaboration of a multidisciplinary team with strong track records in elastic rod theory, engineering and animal comparative physiology.
By formulating a well posed mathematical problem, MMEAW will be able to identify optimal conditions for vibrissae and extend the analysis to embrace extreme loadings and deflections, thereby offering a global perspective on how different vibrissae morphologies affect performance. That information can be used by robotics engineers and structural engineers to implement optimal designs for flexible robotic arms and antennae, indeed it carries across to any engineer developing technology that involves long slender flexible structures; whether a robot arm, a building structure (beam, column, strut), a cable buoy system, a space tether, or a medical stent.

Planned Impact

The MMEAW project will discover new things about the variety of animal whiskers. It will examine the varieties of cross sections, of curvatures and tapering and how animals exploit those to their advantage, whether that be burrowing, foraging, hunting in water, or processing information on shape, form and texture. Whilst that may be of interest to comparative physiologists and evolutionists, MMEAW is primarily motivated by engineering considerations, and connects with a long UK tradition of developing bio-inspired technology.

Indeed MMEAW has potential for impacting on the design and development of any technological device that can be described as long, slender, elastic and load bearing. That device may be a flexible robotic arm used for exploring areas where vision is restricted and/or where surface texture is important. For structural engineers, it can apply to any long slender structural load bearing component used in buildings; for example, beams, struts and columns. For marine engineers, it may be a cable buoy system deployed in deep oceans, where cable tangling is a problem. In the textiles industry, it relates to the bending and twisting of yarn. For engineers developing medical technology, it applies to devices such as flexible guide wires used for interventional radiology procedures.

Note, in general, engineers seeking to improve the performance of technology based on rod-like structures, tend to model them as naturally straight and with uniform circular cross sections. Whilst that is the simplest model, such rods are rarely encountered in nature. Engineers will benefit from MMEAW's research because they will learn how combinations of initial curvature, taper and twist impact on the performance of a long slender rod under a range of loading conditions. Furthermore, MMEAW will extend its analysis to specify optimal combinations of taper, curvature, length, weight etc., for particular loading sequences. MMEAW will develop user-friendly simulation software that will allow engineers to study how variations and combinations of those parameters affect the performance of a 'whisker-like' device.

There are other potential beneficiaries of MMEAW - animals themselves! In recent years, engineers have developed early warning systems for manatees, a threatened species (whose whole body is covered with whiskers). That technology was developed on the basis of research that led to understanding of how manatees use their whiskers to detect on-coming boats in the water. Indeed, knowledge and understanding of how mammals use their whiskers to gather information about their surroundings will assist in planning human activities such that they do not adversely impact on threatened species.

Publications

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Dougill G (2020) Ecomorphology reveals Euler spiral of mammalian whiskers. in Journal of morphology

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Grant RA (2018) Whisker touch sensing guides locomotion in small, quadrupedal mammals. in Proceedings. Biological sciences

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Milne AO (2020) Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal. in Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

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Muchlinski MN (2020) Good Vibrations: The Evolution of Whisking in Small Mammals. in Anatomical record (Hoboken, N.J. : 2007)

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Singh P (2018) Critical points of the clamped-pinned elastica in Acta Mechanica

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Singh P (2018) Asymptotic analysis of the clamped-pinned elastica in Archives of Mechanics

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Starostin E (2020) The Euler spiral of rat whiskers in Science Advances

 
Description We have analysed the shapes of over 500 individual vibrissae from 15 rats. This involves two separate and independent data sets. We have found a simple mathematical equation that describes the full variety of those shapes. The results have been published this year.

Science Advances 15 Jan 2020:
Vol. 6, no. 3, eaax5145
DOI: 10.1126/sciadv.aax5145

We have analysed numerous other mammal species; generalising the procedure above to account for taper as well as intrinsic curvature.
The results have been submitted to a journal.

Another paper on the mechanics of whisker sensors is ready to submit.
Exploitation Route This may be useful for
1) researchers studying relationships between growth and form
2) research into the mechanics of vibrissae (neuroscience)
3) Development of tactile robotic devices
Sectors Other

URL https://scienceadvances.altmetric.com/details/74066634/news
 
Description They have been disseminated across a number of popular science web portals. For example, YAHOO NEWS: https://uk.news.yahoo.com/found-special-maths-equation-hidden-142733182.html DAILY HUNT https://m.dailyhunt.in/news/india/english/scroll-epaper-scrol/a+mathematical+equation+hidden+in+rat+whiskers+can+be+used+to+design+railway+tracks-newsid-162994790 PHYSICS WORLD https://physicsworld.com/a/the-euler-spiral-of-rat-whiskers-a-colourful-inca-statue-a-quantum-bottleneck-in-hiring/ CONVERSATION https://theconversation.com/how-we-found-a-special-maths-equation-hidden-in-rat-whiskers-130345 There have been radio/TV and museum events too- see the report
Sector Education,Culture, Heritage, Museums and Collections
Impact Types Cultural

 
Title Data base of whiskers from a range of species 
Description Data base depicting length, curvature and taper for a range of species 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact This data base can be useful in understanding how whisker morphology varies across species, with whisker size scaled according to body size.. For example, it highlights that slender and more flexible whiskers are found on terrestrial mammals. Those whiskers will bend and deflect with relative ease around environmental objects when exploring in tight, enclosed spaces. Aquatic mammals tend to have shorter stiffer whiskers. 
 
Title Data on rat whiskers - their curvatures, lengths and Euler Spiral fits 
Description . The RSD graphs for the Euler spiral fits. Comparison of residual mean square graphs for circular arc (red), Euler spiral (green), and quadratic curvature (blue) fits. Distribution of lengths and the curvature coefficients. Distribution of lengths L and coefficients B and A across the mystacial pad matrix. Violin plots showing distributions of the coefficients B (left) and A (right) relative to individual animals. Distribution of 30 average characteristics of shapes for each mystacial follicle. . Density of whiskers on the universal Euler spiral. Configuration of the right half of the whisker sensory shroud (interactive threedimensional image). Configuration of the right half of the whisker sensory shroud (interactive threedimensional image). . A schematic of a whisker in a planar approximation. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact The associated publication received widespread coverage on popular science websites e.g. https://theconversation.com/how-we-found-a-special-maths-equation-hidden-in-rat-whiskers-130345 https://physicsworld.com/a/the-euler-spiral-of-rat-whiskers-a-colourful-inca-statue-a-quantum-bottleneck-in-hiring/ https://thesciencebreaker.org/breaks/evolution-behaviour/the-rats-euler-whiskers 
URL https://advances.sciencemag.org/content/advances/suppl/2020/01/13/6.3.eaax5145.DC1/aax5145_SM.pdf
 
Description BBC Radio 5 Live Breakfast Show 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact An interview on BBC Radio 5 Live Breakfast Show
Year(s) Of Engagement Activity 2019
 
Description Documentary for Digital Planet on BBC World Service What can we learn from cats' whiskers? 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A documentary on BBC World Service
Year(s) Of Engagement Activity 2020
URL https://www.bbc.co.uk/programmes/p0833vv1
 
Description Life After Dark Manchester Museum, I love Research Event and Science Uncovered European Researchers Night 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Manchester Museum hosted a special late opening showcasing Manchester's finest researchers and their work for an adult audience linked to the European Researchers Night, a Europe wide initiative, in which thousands of researchers all across Europe meet the public and share their work in a social setting. This year's theme is broad: Research in the City: More than half of the world's population lives in urban areas. On one hand, our cities face a range of tough challenges, from climate change, air and water pollution, and flooding, to deprivation, social inequalities and population health. On the other hand, cities are places of innovation and enterprise, art and culture, and science and technology; where great ideas and opportunities are found.
Year(s) Of Engagement Activity 2018
URL https://events.manchester.ac.uk/event/event:mce-jjgzft8v-9ypw78/science-uncovered
 
Description Life in the Dark Natural History Museum, London Exhibition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact This Life in the Dark (2018-19) an exhibition at the Natural History Museum, London Exhibition
This was highly successful, attracting 500,000 visitors.
Year(s) Of Engagement Activity 2018,2019
URL https://www.nhm.ac.uk/visit/exhibitions/life-in-the-dark.html
 
Description Natural History Museum Podcast on how dormice use their whiskers to 'see' in the dark 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Natural History Museum podcast and live youtube channel on how dormice use their whiskers to 'see' in the dark
Year(s) Of Engagement Activity 2018
URL https://www.nhm.ac.uk/discover/dormice-use-whiskers-to-see-in-the-dark
 
Description Paul Ross Show 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact Robyn Grant talked about research on whiskers to Talk Radio
Year(s) Of Engagement Activity 2018
 
Description Platform for Investigation: Active touch sensing in humans, animals and robots 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact An event at Manchester Museum of Science and Industry with 500 attendees
Year(s) Of Engagement Activity 2020
 
Description Tumble Podcast for kids 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact Podcast for kids on Tumble, which is a science podcast for kids, to be enjoyed by the entire family. It relates stories about science discoveries, with the help of scientists, to children
Year(s) Of Engagement Activity 2019
URL https://play.acast.com/s/thetumble/the-science-of-whiskers