2,534 research outputs found
Geometry-based customization of bending modalities for 3D-printed soft pneumatic actuators
In this work, we propose a novel type of 3D-printed soft pneumatic actuator that allows geometry-based customization of bending modalities. While motion in the 3D-space has been achieved for several types of soft actuators, only 2D-bending has been previously modelled and characterized within the scope of 3D-printed soft pneumatic actuators. We developed the first type of 3D-printed soft pneumatic actuator which, by means of the unique feature of customizable cubes at an angle with the longitudinal axis of the structure, is capable of helical motion. Thus, we characterize its mechanical behavior and formulate mathematical and FEA models to validate the experimental results. Variation to the pattern of the inclination angle along the actuator is then demonstrated to allow for complex 3D-bending modalities and the main applications in the fields of object manipulation and wearable robotics are finally discussed
Design and Fabrication of Soft 3D Printed Actuators: Expanding Soft Robotics Applications
Soft pneumatic actuators are ideal for soft robotic applications due to their innate compliance and high power-weight ratios. Presently, the majority of soft pneumatic actuators are used to create bending motions, with very few able to produce significant linear movements. Fewer can actively produce strains in multiple directions. The further development of these actuators is limited by their fabrication methods, specifically the lack of suitable stretchable materials for 3D printing.
In this thesis, a new highly elastic resin for digital light projection 3D printers, designated ElastAMBER, is developed and evaluated, which shows improvements over previously synthesised elastic resins. It is prepared from a di-functional polyether urethane acrylate oligomer and a blend of two different diluent monomers. ElastAMBER exhibits a viscosity of 1000 mPa.s at 40 °C, allowing easy printing at near room temperatures. The 3D-printed components present an elastomeric behaviour with a maximum extension ratio of 4.02 ± 0.06, an ultimate tensile strength of (1.23 ± 0.09) MPa, low hysteresis, and negligible viscoelastic relaxation
Development of novel micropneumatic grippers for biomanipulation
Microbjects with dimensions from 1 μm to 1 mm have been developed
recently for different aspects and purposes. Consequently, the development of
handling and manipulation tools to fulfil this need is urgently required.
Micromanipulation techniques could be generally categorized according to
their actuation method such as electrostatic, thermal, shape memory alloy,
piezoelectric, magnetic, and fluidic actuation. Each of which has its advantage
and disadvantage. The fluidic actuation has been overlooked in MEMS despite
its satisfactory output in the micro-scale.
This thesis presents different families of pneumatically driven, low cost,
compatible with biological environment, scalable, and controllable
microgrippers. The first family demonstrated a polymeric microgripper that
was laser cut and actuated pneumatically. It was tested to manipulate microparticles
down to 200 microns. To overcome the assembly challenges that
arise in this family, the second family was proposed.
The second family was a micro-cantilever based microgripper, where the
device was assembled layer by layer to form a 3D structure. The microcantilevers
were fabricated using photo-etching technique, and demonstrated
the applicability to manipulate micro-particles down to 200 microns using
automated pick-and-place procedure. In addition, this family was used as a
tactile-detector as well. Due to the angular gripping scheme followed by the
above mentioned families, gripping smaller objects becomes a challenging
task. A third family following a parallel gripping scheme was proposed
allowing the gripping of smaller objects to be visible. It comprises a compliant
structure microgripper actuated pneumatically and fabricated using picosecond
laser technology, and demonstrated the capability of gripping microobject
as small as 100 μm microbeads. An FEA modelling was employed to
validate the experimental and analytical results, and excellent matching was
achieved
A Review of Smart Materials in Tactile Actuators for Information Delivery
As the largest organ in the human body, the skin provides the important
sensory channel for humans to receive external stimulations based on touch. By
the information perceived through touch, people can feel and guess the
properties of objects, like weight, temperature, textures, and motion, etc. In
fact, those properties are nerve stimuli to our brain received by different
kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can
stimulate these receptors and cause different information to be conveyed
through the nerves. Technologies for actuators to provide mechanical,
electrical or thermal stimuli have been developed. These include static or
vibrational actuation, electrostatic stimulation, focused ultrasound, and more.
Smart materials, such as piezoelectric materials, carbon nanotubes, and shape
memory alloys, play important roles in providing actuation for tactile
sensation. This paper aims to review the background biological knowledge of
human tactile sensing, to give an understanding of how we sense and interact
with the world through the sense of touch, as well as the conventional and
state-of-the-art technologies of tactile actuators for tactile feedback
delivery
DEVELOPMENT OF A SOFT PNEUMATIC ACTUATOR FOR MODULAR ROBOTIC MECHANISMS
Soft robotics is a widely and rapidly growing field of research today. Soft
pneumatic actuators, as a fundamental element in soft robotics, have gained
huge popularity and are being employed for the development of soft robots.
During the last decade, a variety of hyper-elastic robotic systems have been
realized. As the name suggests, such robots are made up of soft materials,
and do not have any underlying rigid mechanical structure. These robots are
actuated employing various methods like pneumatic, electroactive, jamming
etc. Generally, in order to achieve a desired mechanical response to produce
required actuation or manipulation, two or more materials having different
stiffness are utilized to develop a soft robot. However, this method introduces
complications in the fabrication process as well as in further design
flexibility and modifications. The current work presents a design scheme of
a soft robotic actuator adapting an easier fabrication approach, which is economical
and environment friendly as well.
The purpose is the realization of a soft pneumatic actuator having functional
ability to produce effective actuation, and which is further employable
to develop modular and scalable mechanisms. That infers to scrutinize the
profile and orientation of the internal actuation cavity and the outer shape of
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the actuator. Utilization of a single material for this actuator has been considered
to make this design scheme convenient. A commercial silicone rubber
was selected which served for an economical process both in terms of the
cost as well as its accommodating fabrication process through molding. In
order to obtain the material behavior, \u2018Ansys Workbench 17.1 R
\u2019 has been
used. Cubic outline for the actuator aided towards the realization of a body
shape which can easily be engaged for the development of modular mechanisms
employing multiple units. This outer body shape further facilitates
to achieve the stability and portability of the actuator. The soft actuator has
been named \u2018Soft Cubic Module\u2019 based on its external cubic shape. For the
internal actuation cavity design, various shapes, such as spherical, elliptical
and cylindrical, were examined considering their different sizes and orientations
within the cubic module. These internal cavities were simulated in order
to achieve single degree of freedom actuation. That means, only one face
of the cube is principally required to produce effective deformation. \u2018Creo
Perametric 3.0 M 130\u2019 has been used to design the model and to evaluate the
performance of actuation cavities in terms of effective deformation and the
resulting von-mises stress. Out of the simulated profiles, cylindrical cavity
with desired outcomes has been further considered to design the soft actuator.
\u2018Ansys Workbench 17.1 R
\u2019 environment was further used to assess the
performance of cylindrical actuation cavity. Evaluation in two different simulation
environments helped to validate the initially achieved results. The
developed soft cubic actuator was then employed to develop different mechanisms
in a single unit configuration as well as multi-unit robotic system
developments.
This design scheme is considered as the first tool to investigate its capacity
to perform certain given tasks in various configurations. Alongside
its application as a single unit gripper and a two unit bio-mimetic crawling
mechanism, this soft actuator has been employed to realize a four degree
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of freedom robotic mechanism. The formation of this primitive soft robotic
four axis mechanism is being further considered to develop an equivalent
mechanism similar to the well known Stewart platform, with advantages of
compactness, simpler kinematics design, easier control, and lesser cost.
Overall, the accomplished results indicate that the design scheme of Soft
Cubic Module is helpful in realizing a simple and cost-effective soft pneumatic
actuator which is modular and scalable. Another favourable point of
this scheme is the use of a single material with convenient fabrication and
handling
Low cost angular displacement sensors for biomechanical applications - a review
In the general scientific quest for increased quality of life a natural ambition is to know more about human body kinematics. Varied knowledge can be extracted from sensors placed on human body and through associated biomechanical parameter evaluation the causal connection between different biomechanical parameters and medical conditions can be inferred. From a biomechanical point of view, one of the most important parameters within the human body is the amplitude of angular movements of joints. Although many angular sensors are used in industry, particular characteristics such as small size, flexibility and appropriate attachment methods must be taken into consideration when estimating the amplitude of movement of human joints. This paper reviews the existing low cost easy to manipulate angular sensors listed in the scientific literature, which currently are or could be used in rehabilitation engineering, physiotherapy or biomechanical evaluations in sport. The review is carried out in terms of a classification based on the sensors’ working principles and includes resistive, capacitive, magnetic and piezoresistive sensors
Mechatronics of systems with undetermined configurations
This work is submitted for the award of a PhD by published works. It deals with some of the efforts of the author over the last ten years in the field of Mechatronics.
Mechatronics is a new area invented by the Japanese in the late 1970's, it consists of a synthesis of computers and electronics to improve mechanical systems. To control any
mechanical event three fundamental features must be brought together: the sensors used to observe the process, the control software, including the control algorithm used and
thirdly the actuator that provides the stimulus to achieve the end result. Simulation, which plays such an important part in the Mechatronics process, is used in both in continuous and discrete forms. The author has spent some considerable time developing skills in all these areas.
The author was certainly the first at Middlesex to appreciate the new developments in Mechatronics and their significance for manufacturing. The author was one of the first mechanical engineers to recognise the significance of the new transputer chip. This was applied to the LQG optimal control of a cinefilm copying process. A 300% improvement in operating speed was achieved, together with tension control.
To make more efficient use of robots they have to be made both faster and cheaper. The author found extremely low natural frequencies of vibration, ranging from 3 to 25 Hz. This limits the speed of response of existing robots. The vibration data was some of the earliest available in this field, certainly in the UK. Several schemes have been devised to control the flexible robot and maintain the required precision.
Actuator technology is one area where mechatronic systems have been the subject of intense development. At Middlesex we have improved on the Aexator pneumatic muscle actuator, enabling it to be used with a precision of about 2 mm.
New control challenges have been undertaken now in the field of machine tool chatter and the prevention of slip. A variety of novel and traditional control algorithms have been investigated in order to find out the best approach to solve this problem
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