35 research outputs found
Incompressible Squeeze-Film Levitation
Transverse vibrations can induce the non-linear compression of a thin film of
air to levitate objects, via the squeeze film effect. This phenomenon is well
captured by the Reynolds' lubrication theory, however, the same theory fails to
describe this levitation when the fluid is incompressible. In this case, the
computation predicts no steady-state levitation, contradicting the documented
experimental evidence. In this letter, we uncover the main source of the
time-averaged pressure asymmetry in the incompressible fluid thin film, leading
the levitation phenomenon to exist. Furthermore, we reveal the physical law
governing the steady-state levitation height, which we confirm experimentally
Mechanically-Inflatable Bio-Inspired Locomotion for Robotic Pipeline Inspection
Pipelines, vital for fluid transport, pose an important yet challenging
inspection task, particularly in small, flexible biological systems, that
robots have yet to master. In this study, we explored the development of an
innovative robot inspired by the ovipositor of parasitic wasps to navigate and
inspect pipelines. The robot features a flexible locomotion system that adapts
to different tube sizes and shapes through a mechanical inflation technique.
The flexible locomotion system employs a reciprocating motion, in which groups
of three sliders extend and retract in a cyclic fashion. In a
proof-of-principle experiment, the robot locomotion efficiency demonstrated
positive linear correlation (r=0.6434) with the diameter ratio (ratio of robot
diameter to tube diameter). The robot showcased a remarkable ability to
traverse tubes of different sizes, shapes and payloads with an average of (70%)
locomotion efficiency across all testing conditions, at varying diameter ratios
(0.7-1.5). Furthermore, the mechanical inflation mechanism displayed
substantial load-carrying capacity, producing considerable holding force of (13
N), equivalent to carrying a payload of approximately (5.8 Kg) inclusive the
robot weight. This novel soft robotic system shows promise for inspection and
navigation within tubular confined spaces, particularly in scenarios requiring
adaptability to different tube shapes, sizes, and load-carrying capacities.
This novel design serves as a foundation for a new class of pipeline inspection
robots that exhibit versatility across various pipeline environments,
potentially including biological systems.Comment: Accepted paper for RoboSoft 202
Tsetse fly inspired steerable bone drill—a proof of concept
The fixation strength of pedicle screws could be increased by fixating along the much stronger cortical bone layer, which is not possible with the current rigid and straight bone drills. Inspired by the tsetse fly, a single-plane steerable bone drill was developed. The drill has a flexible transmission using two stacked leaf springs such that the drill is flexible in one plane and can drill along the cortical bone layer utilizing wall guidance. A proof-of-principle experiment was performed which showed that the Tsetse Drill was able to successfully drill through 5, 10 and 15 PCF cancellous bone phantom which has similar mechanical properties to severe osteoporotic, osteoporotic and healthy cancellous bone. Furthermore, the Tsetse Drill was able to successfully steer and drill along the cortical wall utilizing wall guidance for an insertion angle of 5°, 10° and 15°. The experiments conclude that the tsetse fly-inspired drilling method is successful and even allows the drilling along the cortical bone layer. The Tsetse Drill can create curved tunnels utilizing wall guidance which could increase the fixation strength of bone anchors and limit the risk of cortical breach and damage to surrounding anatomy
A Retrofit Sensing Strategy for Soft Fluidic Robots
Soft robots are intrinsically capable of adapting to different environments
by changing their shape in response to interaction forces with the environment.
However, sensing and feedback are still required for higher level decisions and
autonomy. Most sensing technologies developed for soft robots involve the
integration of separate sensing elements in soft actuators, which presents a
considerable challenge for both the fabrication and robustness of soft robots
due to the interface between hard and soft components and the complexity of the
assembly. To circumvent this, here we present a versatile sensing strategy that
can be retrofitted to existing soft fluidic devices without the need for design
changes. We achieve this by measuring the fluidic input that is required to
activate a soft actuator and relating this input to its deformed state during
interaction with the environment. We demonstrate the versatility of our sensing
strategy by tactile sensing of the size, shape, surface roughness and stiffness
of objects. Moreover, we demonstrate our approach by retrofitting it to a range
of existing pneumatic soft actuators and grippers powered by positive and
negative pressure. Finally, we show the robustness of our fluidic sensing
strategy in closed-loop control of a soft gripper for practical applications
such as sorting and fruit picking. Based on these results, we conclude that as
long as the interaction of the actuator with the environment results in a shape
change of the interval volume, soft fluidic actuators require no embedded
sensors and design modifications to implement sensing. We believe that the
relative simplicity, versatility, broad applicability and robustness of our
sensing strategy will catalyze new functionalities in soft interactive devices
and systems, thereby accelerating the use of soft robotics in real world
applications
Catheter steering in interventional cardiology: Mechanical analysis and novel solution
In recent years, steerable catheters have been developed to combat the effects of the dynamic cardiac environment. Mechanically actuated steerable catheters appear the most in the clinical setting; however, they are bound to a number of mechanical limitations. The aim of this research is to gain insight in these limitations and use this information to develop a new prototype of a catheter with increased steerability. The main limitations in mechanically steerable catheters are identified and analysed, after which requirements and solutions are defined to design a multi-steerable catheter. Finally, a prototype is built and a proof-of-concept test is carried out to analyse the steering functions. The mechanical analysis results in the identification of five limitations: (1) low torsion, (2) shaft shortening, (3) high unpredictable friction, (4) coupled tip-shaft movements, and (5) complex cardiac environment. Solutions are found to each of the limitations and result in the design of a novel multi-steerable catheter with four degrees of freedom. A prototype is developed which allows the dual-segmented tip to be steered over multiple planes and in multiple directions, allowing a range of complex motions including S-shaped curves and circular movements. A detailed analysis of limitations underlying mechanically steerable catheters has led to a new design for a multi-steerable catheter for complex cardiac interventions. The four integrated degrees of freedom provide a high variability of tip directions, and repetition of the bending angle is relatively simple and reliable. The ability to steer inside the heart with a variety of complex shaped curves may potentially change conventional approaches in interventional cardiology towards more patient-specific and lower complexity procedures. Future directions are headed towards further design optimizations and the experimental validation of the prototype
A Retrofit Sensing Strategy for Soft Fluidic Robots
<p>This replication package contains the raw data and processing codes for all the figures in the manuscript titled A Retrofit Sensing Strategy for Soft Fluidic Robots.</p>