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"Pneumatics"
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The atmosphere of heaven : the unnatural experiments of Dr Beddoes and his sons of genius
Medical historian Mike Jay charts the chaotic rise and fall of the Pneumatic Institute in this fast-paced account, and reveals its crucial influence - on modern drug culture, attitudes toward objective and subjective knowledge, the development of anaesthetic surgery, and the birth of the Romantic movement.
Book
Design Analysis and Cost Optimisation of a Multi-Hole Trim Using Cfd in Control Valves
An experimental and numerical study has been performed on a 4-inch globe control valve with the objective of diagnosing local flow behavior and quantifying the different flow parameters to the total valve performance. A computer-based data acquisition system, coupled with pressure transducers, were used to obtain experimental measurements of both the upstream and downstream pressures to calculate pressure drop across the valve. The acquired data was used to validate the results of numerical simulations. Four models of single stage multi-hole trims with different hole sizes were numerically studied. The pressure-drop and hence flow coefficient (Cv) of individual holes were quantified. Flow coefficient (Cv) is defined as defined as the volume of water in gallons per minute (GPM) at 60°F that will flow through a fully open valve with a pressure differential of 1 psi across the valve. The flow behavior around the trim was obtained, and these provided valuable insight into the mechanisms that determine the performance of a multi-hole trim. These were used to establish the relationship between the flow coefficient of the valve with passageways in the cage. The focus of the study was directed towards the development and optimization of a single stage multi-hole trim for a globe control valve. Relationships between parameters such as trim hole diameter, hole height (row position) and hole angular position were examined extensively. The results were used to develop a series of analytical expressions to represent the effect of each geometrical feature and predict local Cv. It is envisaged that proposed expressions will feed into current design methodologies for control valve multi-hole trims which offers the prospect of improved overall performance. The final part of the study was to optimise the control valve through a least cost method where the valve selection is based on total cost as a function of valve diameter. A case study example is discussed to show the control valve life cycle cost which has been incorporated in the optimised design.
Dissertation
Innovative Systems for Incremental Positioning in Pneumatics
This article presents the structure and functioning of two pneumatic linear incremental positioning systems and the experimental models designed and built, in order to determine their performances.
Journal Article
Programmable soft valves for digital and analog control
In soft devices, complex actuation sequences and precise force control typically require hard electronic valves and microcontrollers. Existing designs for entirely soft pneumatic control systems are capable of either digital or analog operation, but not both, and are limited by speed of actuation, range of pressure, time required for fabrication, or loss of power through pull-down resistors. Using the nonlinear mechanics intrinsic to structures composed of soft materials—in this case, by leveraging membrane inversion and tube kinking—two modular soft components are developed: a piston actuator and a bistable pneumatic switch. These two components combine to create valves capable of analog pressure regulation, simplified digital logic, controlled oscillation, nonvolatile memory storage, linear actuation, and interfacing with human users in both digital and analog formats. Three demonstrations showcase the capabilities of systems constructed from these valves: 1) a wearable glove capable of analog control of a soft artificial robotic hand based on input from a human user’s fingers, 2) a human-controlled cushion matrix designed for use in medical care, and 3) an untethered robot which travels a distance dynamically programmed at the time of operation to retrieve an object. This work illustrates pathways for complementary digital and analog control of soft robots using a unified valve design.
Journal Article
Adjunctive Intermittent Pneumatic Compression for Venous Thromboprophylaxis
Patients admitted to an ICU were randomly assigned to receive intermittent pneumatic compression plus pharmacologic thromboprophylaxis or pharmacologic thromboprophylaxis alone. Adjunctive intermittent pneumatic compression did not result in a significantly lower incidence of proximal lower-limb deep-vein thrombosis.
Journal Article
Design, Fabrication, and Performance Test of a New Type of Soft-Robotic Gripper for Grasping
This investigation presents a novel soft-robotic pneumatic gripper that consists of three newly proposed soft actuators. The newly proposed soft actuators adopt a composite structure of two kinds of pneumatic networks which can work independently and play their respective roles in grasping. The design, analyses, and fabrication of the proposed soft actuators are introduced systematically, and then an experimental system is built to examine the output characteristics of the soft actuator. Compared with the conventional single pneumatic network-based soft actuator, the newly proposed one combines the advantages of the two pneumatic networks, and it employs a larger output force and retains desired bending deformation ability at the same time. The grasping performance test results show that the new soft gripper constituted by the proposed soft actuators has high reliability and stability whether in pinching or in enveloping grasping, and it is also competent for grasping heavier or irregular objects, demonstrating the feasibility and effectiveness of the newly proposed soft actuator, and giving it a good and wide application prospect.
Journal Article
Comparison of Different Technologies for Soft Robotics Grippers
Soft grippers have experienced a growing interest due to their considerable flexibility that allows them to grasp a variety of objects, in contrast to hard grippers, which are designed for a specific item. One of their most remarkable characteristics is the ability to manipulate soft objects without damaging them. This, together with their wide range of applications and the use of novels materials and technologies, renders them a very robust device. In this paper, we present a comparison of different technologies for soft robotics grippers. We fabricated and tested four grippers. Two use pneumatic actuation (the gripper with chambered fingers and the jamming gripper), while the other two employ electromechanical actuation (the tendon driver gripper and the gripper with passive structure). For the experiments, a group of twelve objects with different mechanical and geometrical properties have been selected. Furthermore, we analyzed the effect of the environmental conditions on the grippers, by testing each object in three different environments: normal, humid, and dusty. The aim of this comparative study is to show the different performances of different grippers tested under the same conditions. Our findings indicate that we can highlight that the mechanical gripper with a passive structure shows greater robustness.
Journal Article
Design and experiment of a parallel dual-channel end-wrapping soft pneumatic actuator
Soft pneumatic actuators, due to their flexibility and ease of deformation, have great application potential in industries such as gripping and handling. The paper presents the design of a parallel dual-channel end-wrapping pneumatic gripper based on a PneuNet-type soft pneumatic actuator. The actuator’s gripping force at the end is enhanced by utilizing two rows of chambers in the dual-channel body, while the wrapping chambers on both sides of the actuator’s end increase the contact area between the actuator and the object being grasped, thereby effectively improving the gripping performance. The reliability of the actuator was verified through a combination of simulations and experiments. Compared to traditional PneuNet soft pneumatic actuators, the actuator designed in this study achieved an end gripping force of up to 1.94 N. Additionally, an experimental platform was constructed, and a pneumatic soft gripper with adjustable spacing was developed. Gripping experiments were conducted on sand molds and other fragile objects with delicate surfaces. The results demonstrated that the soft pneumatic gripper designed in this study applies to a wider range of gripping scenarios compared to mechanical grippers, providing greater gripping force and stability than conventional soft pneumatic grippers.
Journal Article
Soft and flexible robot skin actuator using multilayer 3D pneumatic network
Actuators are an essential part of a robot, creating movement between the robot and its environment. Actuators with thin and flexible shapes can operate in a wider variety of environments, and actuators with multiple degrees of freedom can generate more complex movements. Here, we propose a soft pneumatic actuator in the form of a thin, flexible sheet that can generate different motion vector fields on its surface. The actuator contains dozens of thin pneumatic chambers and multi-channel pneumatic circuits connecting them in its thin body, converting input pressure into complex surface movements. Depending on the pressure sequence, it can produce surface movements in six different directions, at different speeds, and over different distances. The versatility of the proposed actuator is demonstrated through tasks such as obstacle removal in narrow pipes, in-hand manipulation, and underwater object transport.
The authors report a flexible sheet-type robot that mimics the movement of myosin. With the characteristics of myosin, the robot was able to generate multi-degree-of-freedom movements while being transformed to fit various narrow spaces.
Journal Article