Applications of Bio-inspired Suction in Robotics

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Suction is an adhesion strategy with a long history, which can be traced back to 1500 B.C.
From medicine, e.g., the cupping therapy and surgical tools, to industry, artificial suction
cups are widely used nowadays. Although the origin of artificial suction cups cannot be
confirmed to be inspired by biological suckers, there is no doubt that natural biological suckers,
e.g. octopus suckers, inspired the development of modern artificial suction cups. From the 1860s
when the modern artificial suction cup was invented, it became one of the most popular industrial
grippers in automated manufacturing and assembly, and also plays important roles in daily
life, transportation and medicine. The wide use of suction cups comes from the low cost, easy
fabrication and high energy efficiency of suction adhesion in contrast to other adhesion strategies.
Therefore, studying the underlying principle and developing next-generation suction cups is of
great significance.
However, up-to-date artificial suction cups are still far from realizing the extraordinary
suction abilities of natural suction organs. To be clear, “suction cups” only refers to artificial ones,
and “suckers” refers to biological ones. On the one hand, artificial suction cups lack the adaptive
suction ability of biological suckers. Although air ejectors can help artificial suction cups grip
irregular and rough objects, they consume too significant energy and are a burden with respect
to size, weight and cost. In contrast, octopus suckers utilize their unique structure, which is a
result of millions of years of evolution, to achieve highly adaptive but still energy-efficient suction.
On the other hand, there are still some functionalities of biological suckers that have not been
explored by artificial suction cups, for example, the suction-involved sliding ability of gastropods.
It can be expected that biological suckers will continue to inspire and encourage the development
of artificial suction cups in the following decades.
In this thesis, we focus on improving the suction adaptation and expanding suction grippers’
functionality. By studying the structure and working principle of biological suckers, in particular,
octopus suckers and gastropod suction abdomens, we propose several octopus-inspired and
gastropod-inspired advanced suction mechanisms. We first propose an octopus-inspired shapeconformable suction (SCS) mechanism, which enables suction cups to adhere to irregularly shaped
surfaces by compressing a multi-layer soft structure. Based on the shape-conformable suction
mechanism, suction cups successfully grip irregular objects, such as highly curved bottles and
uneven toothpaste tubes. We then propose an octopus-inspired mucus-enhanced suction (MES)
mechanism, which enables suction cups to adaptively adhere to rough surfaces by introducing
mucus into the suction interface. Based on the mucus-enhanced suction mechanism, suction
cups successfully grip 120-grit rough sandpapers. Combining the shape-conformable suction
and mucus-enhanced suction mechanisms, we propose the multiscale suction (MSS) mechanism,
which enables suction cups to adhere to highly curved, rough and dry surfaces, e.g., a stone.
We finally propose a gastropod-inspired sliding suction (SS) mechanism, which enables suction
cups to adhere to the substrate with the freedom of translational and rotational sliding. Based
i
on the sliding suction mechanism, suction cups achieve dexterous and controllable sliding on
walls and ceilings with extremely high energy efficiency and high payload capacity. The success
of our work shows significant potential in a variety of areas. In industry, our work provides
advanced adaptive suction grippers for fruit harvesting, seafood delivery and product packaging.
In medicine, the mucus-enhanced suction mechanism provides a liquid-environment-compatible
anchoring method for in vivo medical tools. The sliding-suction-based climbing robots have great
potential for autonomous transportation, cleaning and inspections on difficult-to-access surfaces,
such as wind turbine blades, hulls of ships and windows of buildings. Lastly, our research also
narrows the gap between biology and robotics, and may be helpful in understanding the structure,
working principle and evolution of biological suckers.
Date of Award19 Mar 2024
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorJonathan M Rossiter (Supervisor) & Hermes Gadelha (Supervisor)

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