Minimalistic Continuum Manipulator Interface Inspired by Fish Scales

Innovation: Academia

University of Bristol

2018

Image: Kyaw Tun / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Manage Compression

When a living system is under compression, there is a force pushing on it, like a chair with a person sitting on it. When evenly applied to all sides of a living system, compression results in decreased volume. When applied on two sides, it results in deformation, such as when pushing on two sides of a balloon. This deformation can be temporary or permanent. Because living systems must retain their most efficient form, they must ensure that any deformation is temporary. Managing compression also provides an opportunity to lessen the effects of other forces. Living systems have strategies to help prevent compression or recover from it, while maintaining function. For example, African elephant adults weigh from 4,700 to 6,048 kilograms. Because they must hold all of that weight on their four feet, the tissues of their feet have features that enable compression to absorb and distribute forces.

Search this Function

Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

Search this Function

Continuum manipulator interface from University of Bristol has a highly articulated helical interface that ensures smooth joint movement.

Benefits

Reduced energy usage
Self-adjusting

Applications

Robotics
Medical treatment
Prosthetics

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure

The Challenge

Continuum manipulators are slender, soft robots that are highly dexterous and deformable. When performing complicated tasks, the reliability of interfaces between moving parts is essential. Small deformations and instabilities can cause the manipulator to fail while performing its task. During certain activities such as surgery an interface failure could be dangerous.

Innovation Details

The continuum manipulator interface is a highly articulated, 3D-printed interface made of UV curable acrylic plastic and hydroxylated wax. The wax temperature is regulated to control joint compliance using a decentralized control approach. Preliminary results have shown task passive shape and task space anisotropic stiffness control.

Biomimicry Story

Fish scales are strong, flexible, and resistant to cracking. The shell is made of fibers arranged in the Bouligand structure, a structure similar to a spiral staircase. This structure helps distribute an impact force or the bite of a predator throughout the scale’s shell, minimizing damage.

See Related Content

close up of metallic colored fish scales

Biological Strategy

Amazonian Fish Has Tough Scales to Protect From Predators

Arapaima fish scales are extremely tough because they are made of tissue arranged in the Bouligand structure

References

Journal article

Three-Dimensional-Printable Thermoactive Helical Interface With Decentralized Morphological Stiffness Control for Continuum Manipulators

IEEE Xplore

embedly preview

AskNature