1. Soft Pneumatic Adaptive Finger Grasper
Daniel Nakhaee-Zadeh Gutierrez
Supervisors: Ali Alazmani, Peter Culmer
Introduction & Aim
Materials & Methods Results
Discussion & Conclusions
At the start, a literature review was
perform about the on-going
research and available products in
the market. This created the basis
for the initial design and inspiration
for future applications.
Modelling soft robotics is a highly
complex process since the
behaviour of hyper elastic materials
depends on many parameters in
the design. A 3D model was created
using Solid Works. The model was
tested using finite element analysis
(FEA) in Abaqus. This helps to
identify the performance and
weaknesses of the model and
materials. From the results of the
analysis multiple iterations of the
design were created and tested
before developing the final model.
The moulds for the final design
were modelled and fabricated using
a 3D printer. The soft finger was
produce using an investment
manufacturing technique,
consisting on a wax core, to make
the air chamber and a polymeric
material to create the matrix and
structure of the actuator. Finally,
the wax core was melted and
extracted leaving a hollow cavity.
The internship has been a showcase of the great benefits of research collaboration, as it involved research projects from
mechatronics, computing and engineering. The grasper design and modelling has served as a design study for the possibilities
of soft robotic systems in many applications. At the same time it has been a great environment to develop the design and
engineering skills learnt in the past years. However, the analysis of the deformation and dynamics of the hyper-elastic
materials still is a big limitation in the design of this kind of actuators. At the same type, the fabrication process available for
creating this type of technology isn’t mature enough to replicate the actuators consistently and there are still issues with the
curing process of the polymers.
This project is still on going and the implementation of the whole system hasn’t been done yet. Future work will involve
creating an accurate computer model of the polymer materials and analyse the behaviour of the fabricated soft fingers
studying study their applications. Furthermore, the usability of the grasper can be increased by adding different tools to the
end tip, improving surface contact and adding the sensing capabilities.
Mechanical Engineering Summer Internships 2016
Traditional hard robotics have shown multiple limitations when dealing with more delicate and
minimal environments, such as the human body. Soft robotics can replace traditional robotics in this
situations. The aim of the project was to develop and design a soft pneumatic finger that can grasp
and move objects in a 3D space by adapting to the different shapes and characteristics of the
samples. At the same time, the objective was to implement soft sensing components in the finger, so
the force and pressure on the grasped objects can be optimized. This product could have many
applications in industrial processes like handling delicate edibles or in the medical field as arms for
keyhole surgery.
Inspiration and Literature
Modelling and Design
Mould and Fabrication
During the project a series of finger actuators were created
using multiple materials. The fabrication process involved
multiple trials to ensure a correct alienation of the different
mould parts. Also, multiple process were used to improve the
surface characteristics of the mould such as polymer coatings.
Moreover, a tensile test was performed to the material to
understand its behaviour and eventually create a accurate
model.
A small scale soft grasper (Figure 5 and 6) was produced to test
the design dynamics and deformation using Dragon Skin 00-20,
an optimal and biocompatible polymer. This grasper showed
great performance such as rapid actuation and relaxation and
variable angle of bending. However, this design had a very thick
constraining layer, that limited the range of movements. Finally,
an optimized larger version of the actuator was also designed
for future fabrication and testing.
Figure 2. Soft robotic assistive hand device
Figure 3. Abaqus meshing of the soft finger
Figure 4. 3D CAD of the soft finger moulds
Figure 6. Soft finger in idle and deformed position.
Figure1. Soft Robotic Inc. hand gripper
Pressurised Air
Air Chamber
Constraining Layer
Figure 5. Functioning structure of the soft finger.
Interaction forces between the Walls