Dissertations / Theses on the topic 'Soft sensors and actuators'
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Mitwalli, Ahmed Hamdi. "Polymer gel actuators and sensors." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9969.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. [351]-361).
by Ahmed Hamdi Mitwalli.
Sc.D.
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Yang, Hee Doo. "Design, Manufacturing, and Control of Soft and Soft/Rigid Hybrid Pneumatic Robotic Systems." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/100635.
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Soft robotic systems have recently been considered as a new approach that is in principle better suited for tasks where safety and adaptability are important. That is because soft materials are inherently compliant and resilient in the event of collisions. They are also lightweight and can be low-cost; in general, soft robots have the potential to achieve many tasks that were not previously possible with traditional robotic systems.
In this paper, we propose a new manufacturing process for creating multi-chambered pneumatic actuators and robots. We focus on using fabric as the primary structural material, but plastic films can be used instead of textiles as well. We introduce two different methods to create layered bellows actuators, which can be made with a heat press machine or in an oven. We also describe origami-like actuators with possible corner structures. Moreover, the fabrication process permits the creation of soft and soft/rigid hybrid robotic systems, and enables the easy integration of sensors into these robots. We analyze various textiles that are possibly used with this method, and model bellows actuators including operating force, restoring force, and estimated geometry with multiple bellows. We then demonstrate the process by showing a bellows actuator with an embedded sensor and other fabricated structures and robots.
We next present a new design of a multi-DOF soft/rigid hybrid robotic manipulator. It contains a revolute actuator and several roll-pitch actuators which are arranged in series. To control the manipulator, we use a new variant of the piece-wise constant curvature (PCC) model. The robot can be controlled using forward and inverse kinematics with embedded inertial measurement units (IMUs). A bellows actuator, which is a subcomponent of the manipulator, is modeled with a variable-stiffness spring, and we use the model to predict the behavior of the actuator. With the model, the roll-pitch actuator stiffnesses are measured in all directions through applying forces and torques. The stiffness is used to predict the behavior of the end effector. The robotic system introduced achieved errors of less than 5% when compared to the models, and positioning accuracies of better than 1cm.Doctor of Philosophy
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Paoletta, Giovanni. "Electroactive soft actuators: Modelling and control." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20189/.
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The work done in this master thesis is part of the European project MAGNIFY (1) at the University of Groningen, the Netherlands."MAGNIFY aims to develop a new generation of artificial muscles for robotic systems. The artificial muscle will be realized by using artificial molecular machines, organized in polymer nanofibers and individually controlled by external stimuli''(2)
This thesis focuses on a similar polymer that will be used in the project MAGNIFY. The work presents the analysis and utilization of an electroactive soft actuator, made of polyurethane-based nanofibers. A mat of aligned nanofibers of polyurethane and salt has been fabricated through an electrospinning process and, subsequently, has been rolled up to form a bundle of aligned nanofibers.
Several electromechanical tests have been performed on the bundle, applying a certain voltage and evaluating the force and the displacement generated by the soft actuator. The sampled data of voltage, force, and displacement are then used to identify the nonlinear model of Voltage-Force and Voltage-Displacement link. The second part of this thesis aims to use the model estimated Voltage-Displacement to build a PID controller for position control. It has been shown a possible future application for the soft actuator as a robotic arm. To conclude, an energy analysis has been performed, to compare the energy consumption of the soft-actuator and of an electric linear motor, considering similar maximum output force.
(1)This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 801378.
(2)https://www.magnifyproject.eu/project-overview
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Yang, Dian. "Soft Pneumatic Actuators Using Negative Pressure." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493304.
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Soft robotics is a growing field where scientists and engineers collaborate to design machines that collaborate safely with humans (namely “collaborative robot”), and manipulate soft or delicate objects safely. Soft pneumatic actuators are excellent tools in building soft robots, since both the elastomer used in building the actuators and the air used to power them are naturally compliant. This compliance distributes the contact force over the area of contact, and limits the contact pressure. Soft pneumatic actuators changes shape with pressure, and use strain-limiting components imbedded in an elastomeric enclosure to generate various motions.
This dissertation explores design and fabrication of soft pneumatic actuators by combining vacuum with reversible buckling of elastomeric beams. Buckling is a classical mechanical instability often seen as a failure mode in hard materials. The reversible buckling of elastomeric beams, however, allows buckling to be harnessed as a method to generate a range of motion, and allows the fabrication of actuators that mimic the performance of actuators (i.e. muscles) found in nature.
Chapter 1 provides a short overview of the history of soft pneumatic actuators, and of the use of vacuum instead of pressure as a source of power. Chapter 2 and Appendix I describe rotary soft pneumatic actuators—the buckling actuator—based on vacuum and buckling of elastomeric beams. Chapter 3 and Appendix II describe the design of linear soft pneumatic actuators—vacuum-actuated muscle-inspired pneumatic structures (VAMPs)—based on the same technology, which mimics the mechanical performance and many useful features of human muscle. Chapter 4 and Appendix III describe a design of vacuum-actuated soft linear actuators (VASAs) that overcome the usual limit of one atmosphere in the output pressure by generating a mechanical advantage. Appendix IV demonstrates that the buckling of arrays of elastomeric beams can also be used in building soft metamaterials with useful functions, such as shape memory metamaterials. Beyond soft pneumatics actuators, novel methods of non-damaging manipulations, such as magnetic levitation, can prove useful in orientation and examination of objects (Appendix V, VI).Engineering and Applied Sciences - Engineering Sciences
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Scheidl, Rudolf. "Actuators and Sensors for Smart Systems." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200616.
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Smartness of technical systems relies also on appropriate actuators and sensors. Different to the prevalent definition of smartness to be embedded machine intelligence, in this paper elegance and simplicity of solutions is postulated be a more uniform and useful characterization. This is discussed in view of the current trends towards cyber physical systems and the role of components and subsystems, as well as of models for their effective realization. Current research on actuators and sensing in the fluid power area has some emphasis on simplicity and elegance of solution concepts and sophisticated modeling. This is demonstrated by examples from sensorless positioning, valve actuation, and compact hydraulic power supply.
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Johnson, David Gary. "Integrating sensors and actuators for robotic assembly." Thesis, University of Hull, 1986. http://hydra.hull.ac.uk/resources/hull:11276.
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This thesis addresses the problem of integrating sensors and actuators for closed-loop control of a robotic assembly cell. In addition to the problems of interfacing the physical components of the work-cell, the difficulties of representing sensory feedback at a high level within the robot control program are investigated. A new level of robot programming, called sensor-level programming, is introduced. In this, the movements of the actuators are not given explicitly, but rather are inferred by the programming system to achieve new sensor conditions given by the programmer. Control of each sensor and actuator is distributed through a master-slave hierarchy, with each sensor and actuator having its own slave controller. A protocol for information interchange between each controller and the master is defined. If possible, the control of the kinematics of a robot arm is achieved through the manufacturer's existing control system. Under these circumstances, the actuator slave would be acting as an interface between the generic command codes issued from the central controller, and the syntax of the corresponding control instructions required by the commercial system. Sensor information is preprocessed in the sensor slaves and a set of high-level descriptors, called attributes, are sent to the central controller. Closed-loop control is achieved on the basis of these attributes. The processing of sensor information which is corrupted by noise is investigated. Sources of sensor noise are identified and new algorithms are developed to quantify the noise based on information obtained from the closed-loop servoing. Once the relative magnitudes of the system and measurement noise have been estimated, a Kalman filter is used to weight the sensor information and hence reduce the credibility given to noisy sensors; in the limit ignoring the information completely. The improvements in system performance by processing the sensor information in this way are demonstrated. The sensor-level representation and automatic error processing are embedded in a software control system, which can be used to interface commercial systems as well as purpose-built devices. An'industrial research project associated with the lay-up of carbon-fibre provides an example of its operation. A list of publications resulting from the work in this thesis is given in Appendix E.
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Dogramadzi, Sanja. "Sensors and actuators in computer controlled colonoscopy." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369813.
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Montazami, Reza. "Smart Polymer Electromechanical Actuators for Soft Microrobotic Applications." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28084.
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Ionic electroactive polymer (IEAP) actuators are a class of electroactive polymer devices that exhibit electromechanical coupling through ion transport in the device. They consist of an ionomeric membrane coated with conductive network composites (CNCs) and conductive electrodes on both sides. A series of experiments on IEAP actuators with various types of CNCs has demonstrated the existence of a direct correlation between the performance of actuators and physical and structural properties of the CNCs. Nanostructure of CNC is especially important in hosting electrolyte and boosting ion mobility.
This dissertation presents a series of systematic experiments and studies on IEAP actuators with two primary focuses: 1) CNC nanostructure, and 2) ionic interactions.
A novel approach for fabrication of CNC thin-films enabled us to control physical and structural properties of the CNC thin-films. We, for the first time, facilitated use of layer-by-layer ionic self-assembly technique in fabrication of porous and conductive CNCs based on polymer and metal nanoparticles. Results were porous-conductive CNCs. We have studied the performance dependence of IEAP actuators on nano-composition and structure of CNCs by systematically varying the thickness, nanoparticle size and nanoparticle concentration of CNCs. We have also studied influence of the waveform frequency, free-ions and counterions of the ionomeric membrane on the performance and behavior of IEAP actuators.
Using the LbL technique, we systematically changed the thickness of CNC layers consisting of gold nanoparticles (AuNPs) and poly(allylamine hydrochloride). It was observed that actuators consisting of thicker CNCs exhibit larger actuation curvature, which is evidently due to uptake of larger volume of electrolyte. Actuation response-time exhibited a direct correlation to the sheet-resistance of CNC, which was controlled by varying the AuNP concentration. It was observed that size and type of free-ions and counterion of ionomeric membrane are also influential on the actuation behavior or IEAP actuators and that the counterion of ionomeric membrane participates in the actuation process.Ph. D.
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Ehresman, Jonathan David. "Integration of actuators and sensors into composite structures." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/ehresman/EhresmanJ0809.pdf.
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The need for more efficient wind turbine blades is growing in our society. One step in accomplishing this task would be to make wind turbines blades into smart structures. A smart structure is one that incorporates sensors, complete control systems, and active control devices, in order to shed, or redistribute the load placed on the structure. For wind turbine blades this means changing the shape of the blade profile as it encounters different wind conditions. In order to have active control surfaces functioning on wind turbine blades, the existing blades would have to be retrofitted, and the new blades being manufactured would have to be redesigned. There are different control surfaces to consider: gurney flaps and false wall flaps are two that can perturb the boundary layer across the low pressure side of the wing. A flat plate and blade section test bed will be manufactured in order to gather empirical data from wind tunnel testing. For actuation of the control surface there are many choices: electrical, hydraulic, pneumatic, and electro-hydrostatic. These actuator types will be investigated under a set of criterion to determine the best one for turbine blade application. Sensors will be investigated with respect to their use in sensing strain, temperature, acceleration, humidity, and delamination. Sensors are also used for health monitoring. This helps engineers design under a damage tolerant philosophy as opposed to a safe life structure philosophy. These sensors will be placed into laminates and different surface treatments will be reviewed to find the best configuration for each sensor. The sensor will be cleaned with isopropyl alcohol, dipped in a 20% by mass solution of nitric acid, and submerged in a 20% by mass solution of nitric acid for 10 seconds. Detailed surface images will be taken of sensors with different surface treatments in order to better understand the bonding between the sensor and laminate. These images indicate that submerging the sensors into 20% by mass solution of nitric acid is the best surface treatment.
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Song, Changsik. "Design and synthesis of molecular actuators and sensors." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41554.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
To date, the most successful conducting polymer actuators are based on polypyrrole, which operates through incorporating and expelling counterions and solvent molecules to balance the charges generated by electrochemical stimuli (swelling mechanism). Although significant progress has been made, there still exists a need for developing new materials that would overcome the intrinsic limitations in the swelling mechanism, such as slow diffusion rate, limited expansion volume, etc. Our group has contributed this area with a different approach -- lecular mechanisms, which utilize a dimensional change of a single polymer chain. We propose two types of molecular mechanisms: contracting and expanding. We proposed earlier a calix[4]arenebased molecular actuator for the contracting mechanism, in which p-dimer formation was proposed as a driving force. In this dissertation, we first confirm by model studies that p-dimer formation can indeed be a driving force for the calix[4]arene-based system. We propose another molecular hinge, binaphthol moiety, for the contracting model. The syntheses of polymers with binaphthols and their characterization, including signatures of oligothiophene interactions, are described. Due to its chirality, we examined the possibilities of the binaphthol polymer as a chiral amine sensor. To create actuators that make use of the expanding model, we propose new conjugated seven-membered ring systems with heteroatoms (thiepin with sulfur and azepine with nitrogen) and their syntheses and characterization will be described. Inspired by the fact that sulfoxide has very low extrusion barrier in the related system, we applied the thiepin molecules to create a peroxide sensor.
(cont.) In addition, during the investigation of phenol functional groups in conducting polymers, we found interesting properties that strategic positioning of phenol groups can render a conjugation-broken meta-linked system just as conductive as a fully conjugated para-linked isomeric system.
by Changsik Song.
Ph.D.
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Yun, Yeoheung. "Nanotube Sensors and Actuators in Mechanics and Medicine." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1150836513.
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Aphanuphong, Sutha. "Embedded heaters and sensors for micro SMA actuators." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1458441.
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Frediani, Gabriele. "Enabling wearable soft tactile displays with dielectric elastomer actuators." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/36219.
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Touch is one of the less exploited sensory channels in human machine interactions. While the introduction of the tactile feedback would improve the user experience in several fields, such as training for medical operators, teleoperation, computer aided design and 3D model exploration, no interfaces able to mimic accurately and realistically the tactile feeling produced by the contact with a real soft object are currently available. Devices able to simulate the contact with soft bodies, such as the human organs, might improve the experience. The existing commercially available tactile displays consist of complex mechanisms that limit their portability. Moreover, no devices are able to provide tactile stimuli via a soft interface that can also modulate the contact area with the finger pad, which is required to realistically mimic the contact with soft bodies, as needed for example in systems aimed at simulating interactions with virtual biological tissues or in robot-assisted minimally invasive surgery. The aim of this thesis is to develop such a wearable tactile display based on the dielectric elastomer actuators (DEAs). DEAs are a class of materials that respond to an electric field producing a deformation. In particular, in this thesis, the tactile element consists of a so-called hydrostatically coupled dielectric elastomer actuator (HC-DEAs). HC-DEAs rely on an incompressible fluid that hydrostatically couples a DEA-based active part to a passive part interfaced to the user. The display was also tested within a closed-loop configuration consisting of a hand tracking system and a custom made virtual environment. This proof of concept system allowed for a validation of the abilities of the display. Mechanical and psychophysical tests were performed in order to assess the ability of the system to provide tactile stimuli that can be distinguished by the users. Also, the miniaturisation of the HC-DEA was investigated for applications in refreshable Braille displays or arrays of tactile elements for tactile maps.
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Hua, Sarah T. "The development and characterization of soft robotic contractile actuators." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123287.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-52).
In this paper, I describe the development of a soft-robotic myocardium and pneumatic artificial muscles (PAMs) that replicate the physiological motion of the heart. We were able to generate physiological twisting motion in a confined geometry, but additional actuators would be required to generate physiological force for blood ejection. However, McKibben PAMs with thermoplastic polyurethane (TPU) bladders were too bulky and prevented the embedding of additional actuators. Therefore, multiple alternate PAM designs which occupy minimal unpressurized volume were explored. Of the various bladder and mesh pairings for traditional McKibben PAMs, latex bladders with nylon braided mesh proved the most promising. 2D PAMs with zero volume bladders were also developed: 2D McKibben, 2D Pleated, and 2D Cardiac Geometry PAMs. Candidate PAMs were characterized and compared to the physiological linear contraction (14.7%) and force generation (60N) of the heart. The 2D PAMs successfully reduced the volumetric footprint and were able to generate a maximum force of 0.46 N/cm3 (7mm-width five channel 2D McKibben PAM matrix), close to the amount generated by the baseline TPU PAMs (0.53 N/cm3), and up to 10.1% linear contraction (3mm-width nine channel 2D McKibben PAM matrix). However, none of the PAM matrices characterized were able to meet both linear contractile and force generation targets. With more characterization and iteration, the 2D PAMs seem promising for the biomimetic soft-robotic myocardium application.
by Sarah T. Hua.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Kadlec, Petr. "On robust and adaptive soft sensors." Thesis, Bournemouth University, 2009. http://eprints.bournemouth.ac.uk/15907/.
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In process industries, there is a great demand for additional process information such as the product quality level or the exact process state estimation. At the same time, there is a large amount of process data like temperatures, pressures, etc. measured and stored every moment. This data is mainly measured for process control and monitoring purposes but its potential reaches far beyond these applications. The task of soft sensors is the maximal exploitation of this potential by extracting and transforming the latent information from the data into more useful process knowledge. Theoretically, achieving this goal should be straightforward since the process data as well as the tools for soft sensor development in the form of computational learning methods, are both readily available. However, contrary to this evidence, there are still several obstacles which prevent soft sensors from broader application in the process industry. The identification of the sources of these obstacles and proposing a concept for dealing with them is the general purpose of this work. The proposed solution addressing the issues of current soft sensors is a conceptual architecture for the development of robust and adaptive soft sensing algorithms. The architecture reflects the results of two review studies that were conducted during this project. The first one focuses on the process industry aspects of soft sensor development and application. The main conclusions of this study are that soft sensor development is currently being done in a non-systematic, ad-hoc way which results in a large amount of manual work needed for their development and maintenance. It is also found that a large part of the issues can be related to the process data upon which the soft sensors are built. The second review study dealt with the same topic but this time it was biased towards the machine learning viewpoint. The review focused on the identification of machine learning tools, which support the goals of this work. The machine learning concepts which are considered are: (i) general regression techniques for building of soft sensors; (ii) ensemble methods; (iii) local learning; (iv) meta-learning; and (v) concept drift detection and handling. The proposed architecture arranges the above techniques into a three-level hierarchy, where the actual prediction-making models operate at the bottom level. Their predictions are flexibly merged by applying ensemble methods at the next higher level. Finally from the top level, the underlying algorithm is managed by means of metalearning methods. The architecture has a modular structure that allows new pre-processing, predictive or adaptation methods to be plugged in. Another important property of the architecture is that each of the levels can be equipped with adaptation mechanisms, which aim at prolonging the lifetime of the resulting soft sensors. The relevance of the architecture is demonstrated by means of a complex soft sensing algorithm, which can be seen as its instance. This algorithm provides mechanisms for autonomous selection of data preprocessing and predictive methods and their parameters. It also includes five different adaptation mechanisms, some of which can be applied on a sample-by-sample basis without any requirement to store the on-line data. Other, more complex ones are started only on-demand if the performance of the soft sensor drops below a defined level. The actual soft sensors are built by applying the soft sensing algorithm to three industrial data sets. The different application scenarios aim at the analysis of the fulfilment of the defined goals. It is shown that the soft sensors are able to follow changes in dynamic environment and keep a stable performance level by exploiting the implemented adaptation mechanisms. It is also demonstrated that, although the algorithm is rather complex, it can be applied to develop simple and transparent soft sensors. In another experiment, the soft sensors are built without any manual model selection or parameter tuning, which demonstrates the ability of the algorithm to reduce the effort required for soft sensor development. However, if desirable, the algorithm is at the same time very flexible and provides a number of parameters that can be manually optimised. Evidence of the ability of the algorithm to deploy soft sensors with minimal training data and as such to provide the possibility to save the time consuming and costly training data collection is also given in this work.
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Chen, Stephanie M. Eng Massachusetts Institute of Technology. "Tactile sensors based on soft polymers." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112836.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 67-69).
Piezoresistive carbon black/polydimethysiloxane (CB/PDMS) is a widely used material in the field of artificial skin development because of its high gauge factor to all forms of stress, including tension, compression and shear. While its durability, inexpensive-ness and customizability make CB/PDMS makes it the quintessential active material for pressure-sensing skin, the material itself has not been well-characterized electrically or mechanically. A series of mechanical tests on 0.625" cubes of CB/PDMS revealed that the material's resistance increases monotonically with strain and that CB/PDMS have similar sensitivities to tension and compression across different CB concentrations. Shear sensitivity, however, was relatively poor and inconsistent between samples. To overcome this lack of sensitivity to shear forces, a hair-inspired "pillar" sensor was designed to detect shear forces. The pillar sensor contains two 2 mm x 2 mm x 28 mm CB/PDMS strain gauges embedded in a 3 mm thick PDMS base, and a silicone pillar that has a 5 mm diameter and 6 mm height. Unlike the CB/PDMS cubes, the pillar sensors were very sensitivity to shear forces and presented resistance changes of up to 10% per 0.5 mm until a deflection angle of 20°. These sensors also have the ability to determine the direction of pillar deflection, exhibiting anisotropic behavior when the sensor is structurally constrained.
by Stephanie Chen.
M. Eng.
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Rostain, William. "Engineering of RNA sensors and actuators in living cells." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/95177/.
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The aim of synthetic biology is to create a new discipline of engineering based on biological parts, devices and systems. The availability of predictable, programmable tools to sense and to control gene expression is central to our ability to engineer such systems. Ribonucleic acid (RNA) is an attractive building material to create such programmable tools, as RNA-RNA interactions are predictable and RNA secondary structure prediction software has been developed. Design rules for creating such parts using RNA can be established, based on a standardised approach or on structural design rules into which function is implicitly encoded. In this latter case, RNA folding software can be used to create RNA sequence which satisfy generalisable structural characteristics, but are tailored to a specific application. In this work, new design rules for the creation of RNA-based sensors and actuators are developed. The actuator parts are based on riboregulators, but with a circular topology generated through splicing of a ribozyme. The ability of these circular riboregulators to activate transcription of gene expression in E. coli cells is demonstrated. A method for improving these actuators by directed evolution is then tested. Finally, design rules for creating sensors of RNAs based Clustered Regularly Interspaced Short Palindromic Repeat guide RNAs (CRISPR gRNAs) are developed. These gRNA-based sensors can switch states and repress gene expression through a CRISPR-Cas9 based platform, but only in the presence of an arbitrary "trigger" RNA. The rules developed for creating sensors and actuators are characterised in E. coli, but are based on general principles that could be used in other organisms including eukaryotic cells.
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Sareen, Harpreet. "Cyborg botany : augmented plants as sensors, displays and actuators." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/114063.
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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 94-98).
Plants are photosynthetic eukaryotes with a billion years of evolutionary history. While primarily sessile, they have developed distinctive abilities to adapt to the environment. They are self-powered, self-fabricating, self-regenerating and active signal networks. They carry highly advanced systems to sense and respond to the environment. We strive for such sensing and responses in our electronics; self growing or self repairing abilities in our architecture; and being sustainable at scale in general. The industrial and technological thought process has mostly been devising artificial means or replicating natural systems synthetically. However, I propose a convergent view of technological evolution with our ecology where techno-plant hybrids are created. The approach is to formulate symbiotic associations and to place the technology in conjunction with the plant function(s). In this thesis, I go from the outside to inside the plants in conceiving such synergetic processes and present case studies of their implementation and analysis. I begin with a robot-plant hybrid where the robotic device adds mobility and is triggered with the plant's own signals. Next, lead (II) detection nanosensors are presented which reside inside the leaf of a plant and continuously sample through plant hydraulics. This is followed with a design study for plants with new conductive channels grown inside them and their subsequent use as inconspicuous motion sensors. I conclude with a symbiotic robot that lives on a sunflower plant and automatically trains or directs its growth with onboard lighting. The end result is an augmented-plant society where technology adds non-native functions or redirects the natural processes..
by Harpreet Sareen.
S.M.
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Kabeya, Kazuhisa III. "Structural Health Monitoring Using Multiple Piezoelectric Sensors and Actuators." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36709.
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A piezoelectric impedance-based structural health monitoring technique was developed at the Center for Intelligent Material Systems and Structures. It has been successfully implemented on several complex structures to detect incipient-type damage such as small cracks or loose connections. However, there are still some problems to be solved before full scale development and commercialization can take place. These include: i) the damage assessment is influenced by ambient temperature change; ii) the sensing area is small; and iii) the ability to identify the damage location is poor. The objective of this research is to solve these problems in order to apply the impedance-based structural health monitoring technique to real structures.
First, an empirical compensation technique to minimize the temperature effect on the damage assessment has been developed. The compensation technique utilizes the fact that the temperature change causes vertical and horizontal shifts of the signature pattern in the impedance versus frequency plot, while damage causes somewhat irregular changes.
Second, a new impedance-based technique that uses multiple piezoelectric sensor-actuators has been developed which extends the sensing area. The new technique relies on the measurement of electrical transfer admittance, which gives us mutual information between multiple piezoelectric sensor-actuators. We found that this technique increases the sensing region by at least an order of magnitude.
Third, a time domain technique to identify the damage location has been proposed. This technique also uses multiple piezoelectric sensors and actuators. The basic idea utilizes the pulse-echo method often used in ultrasonic testing, together with wavelet decomposition to extract traveling pulses from a noisy signal. The results for a one-dimensional structure show that we can determine the damage location to within a spatial resolution determined by the temporal resolution of the data acquisition.
The validity of all these techniques has been verified by proof-of-concept experiments. These techniques help bring conventional impedance-based structural health monitoring closer to full scale development and commercialization.Master of Science
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Lloyd, Justin Michael. "Electrical Properties of Macro-Fiber Composite Actuators and Sensors." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10013.
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Piezoceramic fiber composite (PFC) actuators and sensors offer many advantages over conventional monolithic piezoceramic devices. Conformable, durable and, when equipped with interdigitated electrodes (IDEs), more responsive than regular monolithic devices, PFCs promise to revolutionize the application of piezoelectric materials. Developed by the NASA-Langley Research Center, the Macro-Fiber Composite (MFC) actuator and sensor is the most sophisticated PFC device yet invented. With superior qualities among PFCs in performance, behavior repeatability and manufacturability, the MFC has spawned great interest in the commercial and academic community as a tool in multitudinous engineering applications.
While the MFC's characteristics render it a singularly useful device, limited characterization and modeling research on the MFC exists. Empirically designed and assembled, the MFC is poorly understood, especially in terms of its underlying operating principles, its dependence on design parameters and its electrical properties. The majority of published MFC studies focus on experimental quantification of MFC mechanical and actuation properties, and the research that attempts to model the MFC relies totally on finite element analysis. Published works widely assume that analytical models of the MFC are totally impossible.
Rectifying gaps in the current body of MFC research, this study presents the first accurate analytical model of the static electrical field properties of the MFC. Implementing the techniques of conformal mapping, a branch of complex analysis, the following chapters derive a closed-form, exact analytical solution describing the electrical potential field and electrical field of the MFC's dual-IDE structure. Based on the conformal mapping solution for the MFC's electrical field, the electrical field of the commercially available MFC is examined and analyzed, introducing an intuitive knowledge of the MFC's operation. Demonstrating the utility of this solution in modeling the MFC, this work also predicts the capacitance and induced strain properties of a continuum of potential MFC designs and offers final suggestions on improving the current commercial MFC design. After establishing the theoretical underpinnings of the analytical MFC model, this report derives the conformal mapping solutions for the MFC, discusses the computational application of the resulting equations and then presents the results of numerical analyses executed using the new analytical model.Master of Science
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Ekman, Fredrik. "Development and Evaluation of Textile Actuators." Thesis, Linköpings universitet, Biosensorer och bioelektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130532.
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Existing actuators in robotics are noisy, rigid and not very lifelike in their movements. There is a need for actuators in especially limb prosthetics and exoskeletons that are silent, softly moving and preferably operating on low currents. One such solution is the conducting polymers. Textiles are well researched and there is a wide variety of patterning. Even more important is their reproducibility and how easily they are mass-produced. This thesis work combines conducting polymers with textiles to achieve linear textile actuators. The textiles are coated with the conducting polymer Polypyrrole which has the property of volume change, when a voltage is applied and there is a reservoir of ions accessible. The volume change, expansion and contraction, results in a linear actuation. The force and strain are measured while changing different parameters and the results are evaluated in this thesis.
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Stoyanov, Hristiyan. "Soft nanocomposites with enhanced electromechanical response for dielectric elastomer actuators." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5119/.
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Electromechanical transducers based on elastomer capacitors are presently considered for many soft actuation applications, due to their large reversible deformation in response to electric field induced electrostatic pressure. The high operating voltage of such devices is currently a large drawback, hindering their use in applications such as biomedical devices and biomimetic robots, however, they could be improved with a careful design of their material properties. The main targets for improving their properties are increasing the relative permittivity of the active material, while maintaining high electric breakdown strength and low stiffness, which would lead to enhanced electrostatic storage ability and hence, reduced operating voltage. Improvement of the functional properties is possible through the use of nanocomposites. These exploit the high surface-to-volume ratio of the nanoscale filler, resulting in large effects on macroscale properties.
This thesis explores several strategies for nanomaterials design. The resulting nanocomposites are fully characterized with respect to their electrical and mechanical properties, by use of dielectric spectroscopy, tensile mechanical analysis, and electric breakdown tests. First, nanocomposites consisting of high permittivity rutile TiO2 nanoparticles dispersed in thermoplastic block copolymer SEBS (poly-styrene-coethylene-co-butylene-co-styrene) are shown to exhibit permittivity increases of up to 3.7 times, leading to 5.6 times improvement in electrostatic energy density, but with a trade-off in mechanical properties (an 8-fold increase in stiffness). The variation in both electrical and mechanical properties still allows for electromechanical improvement, such that a 27 % reduction of the electric field is found compared to the pure elastomer. Second, it is shown that the use of nanofiller conductive particles (carbon black (CB)) can lead to a strong increase of relative permittivity through percolation, however, with detrimental side effects. These are due to localized enhancement of the electric field within the composite, which leads to sharp reductions in electric field strength. Hence, the increase in permittivity does not make up for the reduction in breakdown strength in relation to stored electrical energy, which may prohibit their practical use. Third, a completely new approach for increasing the relative permittivity and electrostatic energy density of a polymer based on 'molecular composites' is presented, relying on chemically grafting soft π-conjugated macromolecules to a flexible elastomer backbone. Polarization caused by charge displacement along the conjugated backbone is found to induce a large and controlled permittivity enhancement
(470 % over the elastomer matrix), while chemical bonding, encapsulates the PANI chains manifesting in hardly any reduction in electric breakdown strength, and hence resulting in a large increase in stored electrostatic energy. This is shown to lead to an improvement in the sensitivity of the measured electromechanical response (83 % reduction of the driving electric field) as well as in the maximum actuation strain (250 %). These results represent a large step forward in the understanding of the strategies which can be employed to obtain high permittivity polymer materials with practical use for electro-elastomer actuation.Die Palette von elektro-mechanischen Aktuatoren, basierend auf dem Prinzip weicher dehnbarer Kondensatoren, scheint besonders für Anwendungen in der Medizin und für biomimetische Applikationen unbegrenzt. Diese Wandler zeichnen sich sowohl durch hohe Reversibilität bei großer mechanischer Deformation als auch durch ihre Flexibilität aus, wobei die mechanischen Deformationen durch elektrische Felder induziert werden. Die Notwendigkeit von hoher elektrischer Spannung zur Erzeugung dieser mechanischen Deformationen verzögert jedoch die technisch einfache und breite Markteinführung dieser Technologie. Diesem Problem kann durch eine gezielte Materialmodifikation begegnet werden. Eine Modifikation hat das Ziel, die relative Permittivität zu erhöhen, wobei die Flexibilität und die hohe elektrische Durchbruchsfeldstärke beibehalten werden sollten. Durch eine Materialmodifikation kann die Energiedichte des Materials bedeutend erhöht und somit die notwendige Betriebsspannung des Aktuators herabgesetzt werden. Eine Verbesserung der funktionalen Materialeigenschaften kann durch die Verwendung von Nanokompositen erzielt werden, welche die fundamentalen Eigenschaften der Nanopartikel, d.h. ein gutes Verhältnis von Oberfläche zu Volumen nutzen, um eine gezielte makroskopische Materialmodifikation zu bewirken. Diese Arbeit behandelt die Anwendung innovativer Strategien für die Erzeugung von Nanomaterialien mit hoher Permittivität. Die so erzeugten Materialien und deren relevante Aktuatorkenngrößen werden durch elektrische und mechanische Experimente vollständig erfasst. Mittels der klassischen Mischansätze zur Erzeugung von Kompositmaterialen mit hoher Permittivität konnte durch nichtleitendes Titaniumdioxid TiO2 (Rutile) in einem Thermoplastischen-Block-Co-Polymer SEBS (poly-styrene-co-ethylene-cobutylene-co-styrene) die Permittivität bereits um 370 % erhöht und die elektrische Energiedichte um 570 % gesteigert werden. Diese Veränderungen führten jedoch zu einem signifikanten Anstieg der Steifigkeit des Materials. Aufgrund der positiven Rückkopplung von elektrischen und mechanischen Eigenschaften des Kompositmaterials ermöglicht bereits dieser einfache Ansatz eine Verbesserung der Aktuation, bei einer 27 %-igen Reduktion der Aktuatorbetriebsspannung. Eine direkte Verwendung von leitfähigen Nanopartikeln kann ebenso zu einem Anstieg der relativen Permittivität beitragen, wobei jedoch die Leitfähigkeit dieser Nanopartikel bedeutende Wechselwirkungen verursacht, welche somit die Energiedichte des Materials negativ beeinflusst und die praktische Verwendung dieses Kompositsystems ausschließt. Als ein völlig neuer Ansatz zur Steigerung der relativen Permittivität und Energiedichte und abweichend vom klassischen Mischverfahren, wird die Herstellung eines "Molekularen Komposits", basierend auf einem chemischen Propfverfahren, präsentiert. In diesem Ansatz wird ein π-konjugiertes leitfähiges Polymer (PANI) an die Hauptkette des Elastomers der Polymermatrix gebunden. Die daraus resultierende Ladungsverteilung entlang der Elastomerhauptkette bewirkt eine 470 %-ige Steigerung der Permittivität des "Molekularen Komposits" im Vergleich zur Permittivität des unbehandelten Elastomermaterials. Aufgrund der Verkapselung der chemischen Bindungen der PANI-Kette entstehen kaum negative Rückwirkungen auf die elektrischen und mechanischen Eigenschaften des so erzeugten Komposits. Diese Materialeigenschaften resultieren in einem signifikanten Anstieg der Energiedichte des Materials. Das mittels dieses Verfahrens erzeugte Komposit zeigt sowohl eine Steigerung der Sensitivität der elektromechanischen Antwort (Reduktion des elektrischen Felds um 83 %) als auch eine bedeutende Steigerung der maximalen Aktuation (250 %). Die Ergebnisse und Ideen dieser Arbeit stellen einen wesentlichen Sprung im Verständnis zur Permittivitätssteigerung in Polymermaterialien dar und werden deshalb in der Erforschung und Entwicklung von Elastomeraktuatoren Beachtung finden.
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Yang, Hee Doo. "Modeling and Analysis of a Novel Pneumatic Artificial Muscle and Pneumatic Arm Exoskeleton." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78284.
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The soft robotics field is developing rapidly and is poised to have a wide impact in a variety of applications. Soft robots have intrinsic compliance, offering a number of benefits as compared to traditional rigid robots. Compliance can provide compatibility with biological systems such as the human body and can provide some benefits for human safety and control. Further research into soft robots can be advanced by further development of pneumatic actuators.
Pneumatic actuators are a good fit for exoskeleton robots because of their light weight, small size, and flexible materials. This is because a wearable robot should be human friendly, therefore, it should be light weight, slim, powerful, and simple.
In this paper, a novel pneumatic artificial muscle using soft materials including integrated electronics for wearable exoskeletons is proposed. We describe the design, fabrication, and evaluation of the actuator, as well as the manufacturing process used to create it. Compared to traditional pneumatic muscle actuators such as the McKibben actuator and new soft actuators that were recently proposed, the novel actuator overcomes shortcomings of prior work. This is due to the actuator's very high contraction ratio that can be controlled by the manufacturing process. In this paper, we describe the design, fabrication, and evaluation of a novel pneumatic actuator that can accommodate integrated electronics for displacement and pressure measurements used for data analysis and control. The desired performance characteristics for the actuator were 100 ~ 400N at between 35kPa and 105kPa, and upon testing we found almost 120 ~ 300N which confirms that these actuators may be suitable in soft exoskeleton applications with power requirements comparable to rigid exoskeletons.
Furthermore, a novel soft pneumatic elbow exoskeleton based on the pneumatic actuator concept and manufacturing process is presented. Each structure is designed and manufactured with all fabric. The distally-worn structure is only 300g, which is light weight for an arm exoskeleton, and the design is simple, leading to a low materials cost.Master of Science
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Kostner, Stefan [Verfasser]. "Sensors and Actuators for Single Particles and Cells / Stefan Kostner." Aachen : Shaker, 2010. http://d-nb.info/1124365214/34.
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Savran, Cagri Abdullah 1976. "Broadband active structural control using collocated piezoelectric sensors and actuators." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/89278.
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McCain, Amy Jean. "Shaped actuators and sensors for local control of intelligent structures." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/46445.
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Yung, Jeremy Hoyt 1971. "Compensation methodologies for local control using strain actuators and sensors." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10627.
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Glück, Tobias [Verfasser]. "Soft Landing and Self-Sensing Strategies for Electromagnetic Actuators / Tobias Glück." Aachen : Shaker, 2013. http://d-nb.info/1049382250/34.
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Marchese, Andrew D. (Andrew Dominic). "Design, fabrication, and control of soft robots with fluidic elastomer actuators." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97807.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 223-236).
The goal of this thesis is to explore how autonomous robotic systems can be created with soft elastomer bodies powered by fluids. In this thesis we innovate in the design, fabrication, control, and experimental validation of both single and multi-segment soft fluidic elastomer robots. First, this thesis describes an autonomous fluidic elastomer robot that is both self-contained and capable of rapid, continuum body motion. Specifically, the design, modeling, fabrication, and control of a soft fish is detailed, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot on-board: power, actuation, processing, and control. At the core of the fish's soft body is an array of Fluidic Elastomer Actuators (FEAs). The fish is designed to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared to studies on biological fish. During escape responses, the soft-bodied robot is shown to have similar input-output relationships to those observed in biological fish. The major implication of this portion of the thesis is that a soft fluidic elastomer robot is shown to be both self-contained and capable of rapid body motion. Next, this thesis provides an approach to planar manipulation using soft fluidic elastomer robots. That is, novel approaches to design, fabrication, kinematic modeling, power, control, and planning as well as extensive experimental evaluations with multiple manipulator prototypes are presented. More specifically, three viable manipulator morphologies composed entirely from soft silicone rubber are explored, and these morphologies are differentiated by their actuator structures, namely: ribbed, cylindrical, and pleated. Additionally, three distinct casting-based fabrication processes are explored: lamination-based casting, retractable-pin-based casting, and lost-wax- based casting. Furthermore, two ways of fabricating a multiple DOF manipulator are explored: casting the complete manipulator as a whole, and casting single DOF segments with subsequent concatenation. An approach to closed-loop configuration control is presented using a piecewise constant curvature kinematic model, real-time localization data, and novel fluidic drive cylinders which power actuation. Multi-segment forward and inverse kinematic algorithms are developed and combined with the configuration controller to provide reliable task-space position control. Building on these developments, a suite of task-space planners are presented to demonstrate new autonomous capabilities from these soft robots such as: (i) tracking a path in free-space, (ii) maneuvering in confined environments, and (iii) grasping and placing objects. Extensive evaluations of these capabilities with physical prototypes demonstrate that manipulation with soft fluidic elastomer robots is viable. Lastly, this thesis presents a robotic manipulation system capable of autonomously positioning a multi-segment soft fluidic elastomer robot in three dimensions while subject to the self-loading effects of gravity. Specifically, an extremely soft robotic manipulator morphology that is composed entirely from low durometer elastomer, powered by pressurized air, and designed to be both modular and durable is presented. To understand the deformation of a single arm segment, a static physics-based model is developed and experimentally validated. Then, to kinematically model the multi-segment manipulator, a piece-wise constant curvature assumption consistent with more traditional continuum manipulators is used. Additionally, a complete fabrication process for this new manipulator is defined and used to make multiple functional prototypes. In order to power the robot's spatial actuation, a high capacity fluidic drive cylinder array is implemented, providing continuously variable, closed-circuit gas delivery. Next, using real-time localization data, a processing and control algorithm is developed that generates realizable kinematic curvature trajectories and controls the manipulator's configuration along these trajectories. A dynamic model for this multi-body fluidic elastomer manipulator is also developed along with a strategy for independently identifying all unknown components of the system: the soft manipulator, its distributed fluidic elastomer actuators, as well as its drive cylinders. Next, using this model and trajectory optimization techniques locally-optimal, open-loop control policies are found. Lastly, new capabilities offered by this soft fluidic elastomer manipulation system are validated with extensive physical experiments. These are: (i) entering and advancing through confined three-dimensional environments, (ii) conforming to goal shape-configurations within a sagittal plane under closed-loop control, and (iii) performing dynamic maneuvers we call grabs.
by Andrew D. Marchese.
Ph. D.
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Cormier, Roger. "Isolation of concurrent faults in sensors and actuators in control systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ46290.pdf.
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Tamirisa, Prabhakar A. "Plasma polymerized hydrogel thin films for applications in sensors and actuators." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/19827.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2007.Committee Chair: Hess, Dennis W.; Committee Member: Henderson, Cliff L.; Committee Member: Hunt, William D.; Committee Member: Meredith, J. Carson; Committee Member: Prausnitz, Mark R.
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Sivakumar, Kousik. "Nanowire sensor and actuator." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 5.53 Mb., 108 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435931.
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Ferrell, Cynthia. "Robust Agent Control of an Autonomous Robot with Many Sensors and Actuators." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/6791.
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This thesis presents methods for implementing robust hexpod locomotion on an autonomous robot with many sensors and actuators. The controller is based on the Subsumption Architecture and is fully distributed over approximately 1500 simple, concurrent processes. The robot, Hannibal, weighs approximately 6 pounds and is equipped with over 100 physical sensors, 19 degrees of freedom, and 8 on board computers. We investigate the following topics in depth: distributed control of a complex robot, insect-inspired locomotion control for gait generation and rough terrain mobility, and fault tolerance. The controller was implemented, debugged, and tested on Hannibal. Through a series of experiments, we examined Hannibal's gait generation, rough terrain locomotion, and fault tolerance performance. These results demonstrate that Hannibal exhibits robust, flexible, real-time locomotion over a variety of terrain and tolerates a multitude of hardware failures.
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Obal, Michael Walter. "Vibration control of flexible structures using piezoelectric devices as sensors and actuators." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/12025.
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Szczepanski, Robert Walter. "Optimal placement of actuators and sensors for vibration control using genetic algorithms." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341754.
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Daraji, Ali Hossain Alewai. "Active vibration control of flexible structures by optimally placed sensors and actuators." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2484.
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The active vibration reduction of plane and stiffened plates was investigated using a genetic algorithm based on finite element modelling to optimise the location of sensors and actuators. The main aspects of this work were: Development of a finite element model for a plate stiffened by beams with discrete sensors and actuators bonded to its surface. Development of a finite element program for steel plates with various symmetrical and asymmetrical stiffening and edge conditions. Development of a genetic algorithm program based on the finite element modelling for the optimisation of the location and number of sensor/actuator pairs and feedback gain. Determination of optimum locations and feedback gain for collocated piezoelectric sensors and actuators on steel plates with various symmetrical and asymmetrical stiffening and edge conditions. Development of fitness and objective functions to locate sensors and actuators. Development of fitness and objective functions to determine the optimal number of sensors and actuators. Development of a reduced search space technique for symmetrical problems. Optimisation of vibration reduction control scheme parameters using the genetic algorithm. Optimisation of the number and location of sensor/actuator pairs and feedback gain to reduce material costs and structural weight and to achieve effective vibration reduction. The modelling was validated by comparison with conventional finite element analysis using ANSYS, and by experiment. The modelling was developed using a quadrilateral isoparametric finite element, based on first order shear deformation theory and Hamilton’s principle, which may be arbitrarily stiffened by beams on its edges. The model can be applied to flat plates with or without stiffening, with discrete piezoelectric sensors and actuators bonded to its surfaces. The finite element modelling was tested for flat and stiffened plates with different boundary conditions and geometries, and the results of the first six natural frequencies were validated with the ANSYS package and experimentally. A genetic algorithm placement strategy is proposed to find the global optimal distribution of two, four, six and ten sensor/actuator pairs and feedback gain based on the minimisation of optimal linear quadratic index as an objective function, and applied to a cantilever plate to attenuate the first six modes of vibration. The configuration of this global optimum was found to be symmetrically distributed about the dynamic axes of symmetry and gave higher vibration attenuation than previously published results with an asymmetrical distribution which was claimed to be optimal. Another genetic algorithm placement strategy is proposed to optimise sensor/actuator locations using new fitness and objective functions based on . This is applied to the same cantilever plate, and was also found to give a symmetrical optimal sensor/actuator configuration. As before, it was found that the optimal transducer locations are distributed with the same axes of symmetry and in agreement with the ANSYS results. A program to simulate the active vibration reduction of stiffened plates with piezoelectric sensors and actuators was written in the ANSYS Parametric Design Language (APDL). This makes use of the finite element capability of ANSYS and incorporates an estimator based on optimal linear quadratic and proportional differential control schemes to investigate the open and closed loop time responses. The complexity of the genetic algorithm problem is represented by the number of finite elements, sensor/actuator pairs and modes required to be suppressed giving a very large search space. In this study, this problem was reduced by the development of a new half and quarter chromosomes technique exploiting the symmetries of the structure. This greatly reduces the number of generations, and hence the computing time, required for the genetic algorithm to converge on the global optimal solution. This could be significant when the technique is applied to large and complex structures. Finally, new fitness and objective functions were proposed to optimise the number of sensor/actuator pairs required for effective active vibration reduction in order to reduce the added cost and weight. The number, location and feedback gain were optimised for the same cantilever plate and it was found that two sensor/actuator pairs in optimal locations could be made to give almost as much vibration reduction as ten pairs.
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Huang, Wei-Ping. "Quasilinear Control of Systems with Time-Delays and Nonlinear Actuators and Sensors." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/967.
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This thesis investigates Quasilinear Control (QLC) of time-delay systems with nonlinear actuators and sensors and analyzes the accuracy of stochastic linearization for these systems. QLC leverages the method of stochastic linearization to replace each nonlinearity with an equivalent gain, which is obtained by solving a transcendental equation. The idea of QLC is to stochastically linearize the system in order to analyze and design controllers using classical linear control theory. In this thesis, the existence of the equivalent gain for a closed-loop time-delay system is discussed. To compute the equivalent gain, two methods are explored. The first method uses an explicit but complex algorithm based on delay Lyapunov equation to study the time-delay, while the second method uses Pade approximant. It is shown that, under a suitable criterion, Pade approximant can be effectively applied for QLC of time-delay systems. Furthermore, the method of Saturated-Root Locus (S-RL) is extended to nonlinear time-delay systems. It turns out that, in a time-delay system, S-RL always terminates prematurely as opposed to a delay-free system, which may or may not terminate prematurely. Statistical experiments are performed to investigate the accuracy of stochastic linearization compared to a system without time-delay. The impact of increasing the time-delay in the approach of stochastic linearization is also investigated. Results show that stochastic linearization effectively linearizes a nonlinear time-delay system, even though delays generally degrade accuracy. Overall, the accuracy remains relatively high over the selected parameters. Finally, this approach is applied to pitch control in a wind turbine system as a practical example of a nonlinear time-delay system, and its performance is analyzed to demonstrate the efficacy of the approach.
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Wei, Yu Zhang. "Design and development of new micro-force sensors." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691170.
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Turner, Celine. "An investigation of novel high-speed actuators for soft product assembly and manipulation." Thesis, De Montfort University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391346.
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Mewer, Richard C. "Analysis and Structural Health Monitoring of Composite Plates with Piezoelectric Sensors and Actuators." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/MewerRC2003.pdf.
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Newman, Scott M. "Active damping control of a flexible space structure using piezoelectric sensors and actuators." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23517.
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Approved for public release; distribution is unlimitedThis thesis details the experimental analysis of an active damping control technique applied to the Naval Postgraduate School's Flexible Spacecraft Simulator using piezoceramic sensors and actuators. The mass property of the flexible arm is varied to study the frequency effects on the Positive Position Feedback (PPF) algorithm. Multi-modal dynamics response is analytically studied using a finite-element model of a cantilevered beam while under the influence of three different control laws: a basic law derived rom the Lyapunov Stability Theorem, PPF and Strain Rate Feedback (SRF). The advantages and disadvantages of using PPF and SRF for active damping control are discussed.
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Raykar, Vikas Chandrakant. "Position calibration of acoustic sensors and actuators on distributed general purpose computing platforms." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/39.
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Thesis (M.S.) -- University of Maryland, College Park, 2003.Thesis research directed by: Dept. of Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Hixenbaugh, Franklin D. "A study on piezoelectric actuators and sensors for vibration control of flexible space structures." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA274925.
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Thesis (M.S. in Systems Technology (Space Systems Operations)) Naval Postgraduate School, September 1993.Thesis advisor(s): Brij N. Agrawal. "September 1993." Includes bibliographical references. Also available online.
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Miller, Duncan Lee. "Development of resource-constrained sensors and actuators for in-space satellite docking and servicing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98697.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 171-177).
Most satellites on-orbit today are not intended to physically approach or interact with other spacecraft. However, the robotic servicing of orbiting assets will be an economically desirable (and often scientifically necessary) capability in future space enterprises. With the right set of tools and technologies, satellites will be able to autonomously refuel, repair, or replace each other. This has the potential to extend mission lifetimes, reduce orbital debris and make space more sustainable. Spacecraft may also assemble on-orbit into larger aggregate spaceflight systems, with applications to sparse aperture telescopes, solar power stations, fuel depots and space habitats. The purpose of this thesis is to address the highest risk elements associated with the docking and servicing of satellites: the sensors, actuators, and associated algorithms. First, a peripheral agnostic robotics platform is introduced, upon which a suite of technology payloads may be developed. Next, a flight qualified docking port for small satellites is presented, and the results detailing its operation in a relevant environment are discussed. In addition, we review a high precision relative sensor designed to enable boresight visual docking. The measurements from this optical camera are applied to a nonlinear estimator to provide the highly accurate sensing necessary for docking. Finally, a free-flying robotic arm is examined and modeled as an experimental payload for the SPHERES Facility on the International Space Station.
by Duncan Lee Miller.
S.M.
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Hanzly, Laura Elizabeth. "Functional Protein Based Materials." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/91934.
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The proteins wheat gluten and gelatin were tested for use in biocomposites and soft actuating materials, respectively. In Chapter II, the self-assembly mechanism of trypsin hydrolyzed wheat gluten (THWG) into rigid β-sheets was applied to an aqueous polyvinyl alcohol (PVA) environment. Aqueous PVA was used in order to determine the effects of an aqueous environment other than pure water on THWG self-assembly kinetics and to realize the potential use of THWG as a nanofiller in polymer matrices. THWG was able to self-assemble into anisotropic spikes and agglomerates of spikes called "pompons" through hydrophobic interactions. THWG self-assembly kinetics were retarded in aqueous PVA solutions compared to water, with the highest molecular weight PVA solution showing the slowest self-assembly kinetics. Chapters III and IV explore the potential of gelatin hydrogels for use in soft actuators. A gelatin bilayer system was designed where an active layer swelled more than a passive layer to cause the system to bend/actuate in response to an environmental stimulus. In Chapter III, gelatin layers were chemically crosslinked to different degrees with glutaraldehyde to achieve bilayer bending when placed in water. Curvature of the bilayer system was found to be dependent on the difference in volume swell ratio between the two layers. It was determined that maximum bending occurred when the passive layer swelled to 60% of the swelling of the active layer. Addition of pre-gelatinized starch to the active layer increased layer swelling and bilayer curvature. Treating the starch containing bilayer with -amylase returned the bilayer to its original shape. In Chapter IV, a pH responsive gelatin bilayer was constructed using Type A and Type B gelatin. Type A and Type B gelatin gels had different chemical properties and swelled to different volumes based on the gel solution pH. Bilayers constructed from Type A and Type B gelatin exhibited different degrees of bending when placed in various pH solutions with maximum curvature occuring at pH 10. A cyclic actuator could be formed when the bent bilayers were placed in a minimum of 0.01M NaCl solution. Placement in salt solution resulted in the unbending of the bilayer. Overall, this work demonstrated the various applications of proteins as functional and green materials.Doctor of Philosophy
The majority of plastics consist of synthetic polymers derived from oil that cannot be broken down by the environment (i.e., not biodegradable). Research is underway to develop sustainable, biodegradable materials. Proteins are a biological polymer that have a wide range of chemical, structural, and functional properties; for this reason they are an excellent source material for use in the design of environmental friendly materials. In Chapter II, the ability of wheat gluten protein to self-assemble into rigid, nanosized structures is used to explore the potential of the protein to be used as a biodegradable nanofiller. A nanofiller is added to various materials in order to improve the overall mechanical properties of the material. Wheat gluten is self-assembled in an aqueous polymer environment. The results show that the polymer environment stunts or slows down the self-assembly rate of the protein compared to a pure water environment. Nanometer sized spikes form in the polymer solutions, indicating wheat gluten could be used as a nanofiller in certain materials. Chapters III and IV explore the use of gelatin proteins for applications in soft robotics. Soft robots and their moveable parts, called soft actuators, are deformable and respond to changes in the environment such as pH, light, temperature, etc. For this reason, soft robots are considerable adaptable compared to traditional rigid robots. Designing a soft actuator from gelatin gels would result in a “smart” material that is biocompatible and biodegradable. A gelatin soft actuator is created using a bilayer design in which one layer of the bilayer swells more than the other layer causing the entire system to bend/actuate. Depending on how the bilayer system was fabricated, bending could be achieved based on stimuli such as the presence of water, the presence of a substrate and enzyme, and changes in pH. Overall, this dissertation demonstrates the extraordinary potential for the use of proteins in designing sustainable materials.
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SADLER, DANIEL J. "DEVELOPMENT OF A NEW MAGNETIC INERCONNECTION TECHNOLOGY FOR MAGNETIC MEMS DEVICE APPLICATIONS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin983800458.
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Dobashi, Yuta. "Characterization of ionic polymers : towards applications as soft sensors in medicine." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59565.
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A phenomenon termed the piezoionic effect is described and characterized in various ionic polymers including polymer networks containing aqueous electrolytes (hydrogels) and organic electrolytes. Initial observations suggest that when an ion containing polymer is compressed, a concentration gradient is induced by the pressure differential, leading to an electrical potential difference detectable at electrodes placed at compressed and uncompressed portions of the polymer. The work focuses on the fundamental characterization of the nature of the piezoionic transduction to probe the effects of relative mobilities of the ions present in the system. The effective ion radii due to ion-solvent interactions and electrostatic ion-polymer interactions have been investigated for their contribution in dictating the piezoionic behavior by NMR measurements of the self-diffusion coefficients. The results are qualitatively correlated to the voltage response to mechanical compression of the polymer samples. Following the experiments, a numerical model is developed which incorporates a number of contributing events believed to be taking place in a concerted manner to cause the piezoionic effect. The deformation induced solvent flow is modeled by means of Biot’s constitutive equations on poroelasticity, a combination of thermodynamic equilibrium and Darcy’s law. The Darcy’s flow induced is then used as the input to model transport of dilute species. Here, the convective factor is being continuously modulated by Darcy’s flow, while Fickian diffusion concurrently takes place. The ionic species experience different displacements due to Stokes' drag experienced by the solvation spheres of the ionic species and solvent molecules and the electrostatic interactions between the charged polymer chains and the mobile ions. Furthermore, this non-homogeneous ionic charge distribution yields a voltage distribution via the Poisson’s equation. This voltage distribution is used to account for the migration of ionic species. The following chapter is dedicated to a novel electrochemical method and modelling approach designed to probe various ionic polymers, some electronically conductive and others interpenetrated, to determine the phase-wise contributions to ionic conductivities. Finally, potential applications of the piezoionic polymers as soft sensors in medicine, particularly in unobtrusive and longitudinal monitoring of physical parameters, are discussed and some preliminary prototypes are introduced and ultimate feasibility is assessed.Applied Science, Faculty of
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Emon, Md Omar Faruk. "Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1593542345792441.
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Nowak, Brent Michael. "A conceptual high-resolution MR encoder and torque transducer for precision actuators /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Price, Alexander K. "Development of Integrated Dielectric Elastomer Actuators (IDEAS) : trending towards smarter and smaller soft microfluidic systems." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3749.
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