The development of an adaptive and reactive interface system for lower limb prosthetic application

Deep tissue injury (DTI) is a known problem correlating to the use of a prosthetic by a transtibial amputee (TTA), causing ulcer-like wounds on the residual limb caused by stress-induced cell necrosis. The magnitude of these stresses at the bone tissue interface has been identified computationally, far exceeding those measured at the skin's surface. Limited technology is available to directly target and reduce such cellular loading and actively reduce the risk of DTI from below-knee use. The primary aim of this project was to identify whether a bespoke prosthetic socket system could actively stiffen the tissues of the lower limb. Stabilising the residual tibia during ambulation and reducing stress concentrations on the cells. To achieve this, a proof-of-concept device was designed and manufactured, a system that allowed the change in displacement of a magnet to be responded to by counterbalancing load. The device was evaluated through experimentation on an able-bodied subject wearing an orthotic device designed to replicate the environment of a prosthetic socket. The chosen sensor effector system was validated against vector data generated by the Motek Medical Computer Assisted Rehabilitation Environment (CAREN.) The project explored a new concept of reactive loading of a below-knee prosthesis to reduce tibial/socket oscillation. The evaluation of the device indicated that external loading of the residual limb in such a manner could reduce the magnitude of rotation about the tibia and therefore minimise the conditions by which DTIs are known to occur. Efforts were made to move the design to the next iteration, focusing on implementing the target demographic.Deep tissue injury (DTI) is a known problem correlating to the use of a prosthetic by a transtibial amputee (TTA), causing ulcer-like wounds on the residual limb caused by stress-induced cell necrosis. The magnitude of these stresses at the bone tissue interface has been identified computationally, far exceeding those measured at the skin's surface. Limited technology is available to directly target and reduce such cellular loading and actively reduce the risk of DTI from below-knee use. The primary aim of this project was to identify whether a bespoke prosthetic socket system could actively stiffen the tissues of the lower limb. Stabilising the residual tibia during ambulation and reducing stress concentrations on the cells. To achieve this, a proof-of-concept device was designed and manufactured, a system that allowed the change in displacement of a magnet to be responded to by counterbalancing load. The device was evaluated through experimentation on an able-bodied subject wearing an orthotic device designed to replicate the environment of a prosthetic socket. The chosen sensor effector system was validated against vector data generated by the Motek Medical Computer Assisted Rehabilitation Environment (CAREN.) The project explored a new concept of reactive loading of a below-knee prosthesis to reduce tibial/socket oscillation. The evaluation of the device indicated that external loading of the residual limb in such a manner could reduce the magnitude of rotation about the tibia and therefore minimise the conditions by which DTIs are known to occur. Efforts were made to move the design to the next iteration, focusing on implementing the target demographic

A scoping review of digital fabrication techniques applied to prosthetics and orthotics: Part 1 of 2—Prosthetics

Background: Traditionally, the manufacture of prostheses is time-consuming and labor-intensive. One possible route to improving access and quality of these devices is the digitalizing of the fabrication process, which may reduce the burden of manual labor and bring the potential for automation that could help unblock access to assistive technologies globally. Objectives: To identify where there are gaps in the literature that are creating barriers to decision-making on either appropriate uptake by clinical teams or on the needed next steps in research that mean these technologies can continue on a pathway to maturity. Study design: Scoping literature review. Methods: A comprehensive search was completed in the following databases: Allied and Complementary Medicine Database, MEDLINE, Embase, Global Health Archive, CINAHL Plus, Cochrane Library, Web of Science, Association for Computing Machinery, Institute of Electrical and Electronics Engineers, and Engineering Village, resulting in 3487 articles to be screened. Results: After screening, 130 lower limb prosthetic articles and 117 upper limb prosthetic articles were included in this review. Multiple limitations in the literature were identified, particularly a lack of long-term, larger-scale studies; research into the training requirements for these technologies and the necessary rectification processes; and a high range of variance of production workflows and materials which makes drawing conclusions difficult. Conclusions: These limitations create a barrier to adequate evidence-based decision-making for clinicians, technology developers, and wider policymakers. Increased collaboration between academia, industry, and clinical teams across more of the pathway to market for new technologies could be a route to addressing these gaps

Design, fabrication and stiffening of soft pneumatic robots

Although compliance allows the soft robot to be under-actuated and generalise its control, it also impacts the ability of the robot to exert forces on the environment. There is a trade-off between robots being compliant or precise and strong. Many mechanisms that change robots' stiffness on demand have been proposed, but none are perfect, usually compromising the device's compliance and restricting its motion capabilities. Keeping the above issues in mind, this thesis focuses on creating robust and reliable pneumatic actuators, that are designed to be easily manufactured with simple tools. They are optimised towards linear behaviour, which simplifies modelling and improve control strategies. The principle idea in relation to linearisation is a reinforcement strategy designed to amplify the desired, and limit the unwanted, deformation of the device. Such reinforcement can be achieved using fibres or 3D printed structures. I have shown that the linearity of the actuation is, among others, a function of the reinforcement density and shape, in that the response of dense fibre-reinforced actuators with a circular cross-section is significantly more linear than that of non-reinforced or non-circular actuators. I have explored moulding manufacturing techniques and a mixture of 3D printing and moulding. Many aspects of these techniques have been optimised for reliability, repeatability, and process simplification. I have proposed and implemented a novel moulding technique that uses disposable moulds and can easily be used by an inexperienced operator. I also tried to address the compliance-stiffness trade-off issue. As a result, I have proposed an intelligent structure that behaves differently depending on the conditions. Thanks to its properties, such a structure could be used in applications that require flexibility, but also the ability to resist external disturbances when necessary. Due to its nature, individual cells of the proposed system could be used to implement physical logic elements, resulting in embodied intelligent behaviours. As a proof-of-concept, I have demonstrated use of my actuators in several applications including prosthetic hands, octopus, and fish robots. Each of those devices benefits from a slightly different actuation system but each is based on the same core idea - fibre reinforced actuators. I have shown that the proposed design and manufacturing techniques have several advantages over the methods used so far. The manufacturing methods I developed are more reliable, repeatable, and require less manual work than the various other methods described in the literature. I have also shown that the proposed actuators can be successfully used in real-life applications. Finally, one of the most important outcomes of my research is a contribution to an orthotic device based on soft pneumatic actuators. The device has been successfully deployed, and, at the time of submission of this thesis, has been used for several months, with good results reported, by a patient

Integrated Methodologies and Technologies for the Design of Advanced Biomedical Devices

Biomedical devices with tailored properties were designed using advanced methodologies and technologies. In particular, design for additive manufacturing, reverse engineering, material selection, experimental and theoretical analyses were properly integrated. The focus was on the design of: i) 3D additively manufactured hybrid structures for cranioplasty; ii) technical solutions and customized prosthetic devices with tailored properties for skull base reconstruction after endoscopic endonasal surgery; iii) solid-lattice hybrid structures with optimized properties for biomedical applications. The feasibility of the proposed technical solutions was also assessed through virtual and physical models

Augmented interaction for custom-fit products by means of interaction devices at low costs

This Ph.D thesis refers to a research project that aims at developing an innovative platform to design lower limb prosthesis (both for below and above knee amputation) centered on the virtual model of the amputee and based on a computer-aided and knowledge-guided approach. The attention has been put on the modeling tool of the socket, which is the most critical component of the whole prosthesis. The main aim has been to redesign and develop a new prosthetic CAD tool, named SMA2 (Socket Modelling Assistant2) exploiting a low-cost IT technologies (e.g. hand/finger tracking devices) and making the user’s interaction as much as possible natural and similar to the hand-made manipulation. The research activities have been carried out in six phases as described in the following. First, limits and criticalities of the already available modeling tool (namely SMA) have been identified. To this end, the first version of SMA has been tested with Ortopedia Panini and the orthopedic research group of Salford University in Manchester with real case studies. Main criticalities were related to: (i) automatic reconstruction of the residuum geometric model starting from medical images, (ii) performance of virtual modeling tools to generate the socket shape, and (iii) interaction mainly based on traditional devices (e.g., mouse and keyboard). The second phase lead to the software reengineering of SMA according to the limits identified in the first phase. The software architecture has been re-designed adopting an object-oriented paradigm and its modularity permits to remove or add new features in a very simple way. The new modeling system, i.e. SMA2, has been totally implemented using open source Software Development Kit-SDK (e.g., Visualization ToolKit VTK, OpenCASCADE and Qt SDK) and based on low cost technology. It includes: • A new module to automatically reconstruct the 3D model of the residual limb from MRI images. In addition, a new procedure based on low-cost technology, such as Microsoft Kinect V2 sensor, has been identified to acquire the 3D external shape of the residuum. • An open source software library, named SimplyNURBS, for NURBS modeling and specifically used for the automatic reconstruction of the residuum 3D model from medical images. Even if, SimplyNURBS has been conceived for the prosthetic domain, it can be used to develop NURBS-based modeling tools for a range of applicative domains from health-care to clothing design. • A module for mesh editing to emulate the hand-made operations carried out by orthopedic technicians during traditional socket manufacturing process. In addition several virtual widgets have been implemented to make available virtual tools similar to the real ones used by the prosthetist, such as tape measure and pencil. • A Natural User Interface (NUI) to allow the interaction with the residuum and socket models using hand-tracking and haptic devices. • A module to generate the geometric models for additive manufacturing of the socket. The third phase concerned the study and design of augmented interaction with particular attention to the Natural User Interface (NUI) for the use of hand-tracking and haptic devices into SMA2. The NUI is based on the use of the Leap Motion device. A set of gestures, mainly iconic and suitable for the considered domain, has been identified taking into account ergonomic issues (e.g., arm posture) and ease of use. The modularity of SMA2 permits us to easily generate the software interface for each device for augmented interaction. To this end, a software module, named Tracking plug-in, has been developed to automatically generate the source code of software interfaces for managing the interaction with low cost hand-tracking devices (e.g., Leap Motion and Intel Gesture Camera) and replicate/emulate manual operations usually performed to design custom-fit products, such medical devices and garments. Regarding haptic rendering, two different devices have been considered, the Falcon Novint, and a haptic mouse developed in-house. In the fourth phase, additive manufacturing technologies have been investigated, in particular FDM one. 3D printing has been exploited in order to permit the creation of trial sockets in laboratory to evaluate the potentiality of SMA2. Furthermore, research activities have been done to study new ways to design the socket. An innovative way to build the socket has been developed based on multi-material 3D printing. Taking advantage of flexible material and multi-material print possibility, new 3D printers permit to create object with soft and hard parts. In this phase, issues about infill, materials and comfort have been faced and solved considering different compositions of materials to re-design the socket shape. In the fifth phase the implemented solution, integrated within the whole prosthesis design platform, has been tested with a transfemoral amputee. Following activities have been performed: • 3D acquisition of the residuum using MRI and commercial 3D scanning systems (low cost and professional). • Creation of the residual limb and socket geometry. • Multi-material 3D printing of the socket using FDM technology. • Gait analysis of the amputee wearing the socket using a markerless motion capture system. • Acquisition of contact pressure between residual limb and a trial socket by means of Teskan’s F-Socket System. Acquired data have been combined inside an ad-hoc developed application, which permits to simultaneously visualize pressure data on the 3D model of the residual lower limb and the animation of gait analysis. Results and feedback have been possible thanks to this application that permits to find correlation between several phases of the gait cycle and the pressure data at the same time. Reached results have been considered very interested and several tests have been planned in order to try the system in orthopedic laboratories in real cases. The reached results have been very useful to evaluate the quality of SMA2 as a future instruments that can be exploited for orthopedic technicians in order to create real socket for patients. The solution has the potentiality to begin a potential commercial product, which will be able to substitute the classic procedure for socket design. The sixth phase concerned the evolution of SMA2 as a Mixed Reality environment, named Virtual Orthopedic LABoratory (VOLAB). The proposed solution is based on low cost devices and open source libraries (e.g., OpenCL and VTK). In particular, the hardware architecture consists of three Microsoft Kinect v2 for human body tracking, the head mounted display Oculus Rift SDK 2 for 3D environment rendering, and the Leap Motion device for hand/fingers tracking. The software development has been based on the modular structure of SMA2 and dedicated modules have been developed to guarantee the communication among the devices. At present, two preliminary tests have been carried out: the first to verify real-time performance of the virtual environment and the second one to verify the augmented interaction with hands using SMA2 modeling tools. Achieved results are very promising but, highlighted some limitations of this first version of VOLAB and improvements are necessary. For example, the quality of the 3D real world reconstruction, especially as far as concern the residual limb, could be improved by using two HD-RGB cameras together the Oculus Rift. To conclude, the obtained results have been evaluated very interested and encouraging from the technical staff of orthopedic laboratory. SMA2 will made possible an important change of the process to design the socket of lower limb prosthesis, from a traditional hand-made manufacturing process to a totally virtual knowledge-guided process. The proposed solutions and results reached so far can be exploited in other industrial sectors where the final product heavily depends on the human body morphology. In fact, preliminary software development has been done to create a virtual environment for clothing design by starting from the basic modules exploited in SMA2

Design of a Variable Stiffness Passive Layer Jamming Structure for Anthropomorphic Robotic Finger Applications

Soft robots can effectively mimic human hand interface characteristics and facilitate collaborative operations with humans in a safe manner. This dissertation research concerns the design and fabrication of a low cost variable stiffness structure for applications in compliant robotic fingers. A conceptual design of a compact multi-layer structure is proposed for realizing variable stiffness, when applied to underactuated fingers of an anthropomorphic robotic hand. The proposed design comprises thin material layers with clearance that permits a progressive hardening feature while grasping and added design flexibility and tuning of the fingers’ compliance. The design permits stiffness variations in a passive manner in the soft contact regions. The design is realized to ensure ease of scalability and cost-effective fabrication by the ’Additive Manufacturing (AM)’/3D-printing technology. Both the multi-layer structures and the fingers could be fabricated as a single entity, and from a single base material with relatively low elastic modulus. The proposed design also exhibits finite degrees-of-freedom representative of the human finger - The feasibility of the design and its manufacturability are verified through prototype fabrication using a readily available 3D-printing material, namely; 'Thermoplastic PolyUrethane (TPU)' with Young’s Modulus of 25MPa. The chosen material permitted low stiffness of the multi-layer structure in the contact interface under relatively small deformations, while ensuring sufficient rigidity on the non-contact regions of the finger. A finite element (FE) model is formulated considering 3D tetrahedral elements and a nodal-normal contact detection method together with the augmented Lagrange formulation. The model is analyzed to determine the force-displacement characteristics of the structure subject to linearly increasing compressive load, under the assumption of low interface friction. A simplified analytical model of the multi-layer structure is also formulated considering essential boundary and support conditions for each individual layer. The model revealed progressive hardening characteristics of the multilayer structure during compression due to sequential jamming of individual layers. The force-displacement characteristics of the design could thus be varied by varying the multi-layer structure parameters, such as number of layers, thickness of individual layers, material properties, and clearance between the successive layers. It is shown that the simplified analytical model could provide reasonably good estimate of the force-deflection properties of the structure in a computationally efficient manner. The analytical model is subsequently used to investigate the influences of variations in the multilayer structure parameters in a computationally efficient manner. It is shown that the proposed design offers superior tuning flexibility to realize desired force-displacement characteristics of the structure for developing scalable anthropomorphic robotic fingers of a compliant robotic hand, in addition to the cost-effective manufacturability

Wright State University\u27s Symposium of Student Research, Scholarship & Creative Activities from Thursday, October 26, 2023

The student abstract booklet is a compilation of abstracts from students\u27 oral and poster presentations at Wright State University\u27s Symposium of Student Research, Scholarship & Creative Activities on October 26, 2023.https://corescholar.libraries.wright.edu/celebration_abstract_books/1001/thumbnail.jp

Smart Material Prosthetic Ankle: Employing material properties for variable stiffness

The inspiration for this research is the natural graduation in stiffness of the biological ankle, over a wide range of ambulation tasks. The goal is to achieve variable stiffness in the force response of a prosthetic foot, utilizing the properties of smart materials. This thesis presents the design and prototyping of a coupling that utilizes the discontinuous change in viscosity observed in shear thickening fluids. A speed dependent stiffness is achieved with the coupling installed in a system of springs. The coupling design presented is used in the modification of a commercially available prosthetic foot. The stiffness of the prototype foot depends on the rate of movement, ranging from a dissipating support at very slow walking speed, to efficient energy storage and return at normal walking speed. Providing energy return during walking is an important design objective for passive prosthetic feet. The objective of this work is to design a prosthetic foot that provides a damped compliant support for slow ambulation without sacrificing the spring like energy return that is beneficial in normal walking. The function of the original prosthetic foot was analyzed in a finite element model to acquire the parameters for the improved design. The coupling was developed and characterized by uniaxial testing. A prototype prosthetic foot was designed and built, and the speed dependent stiffness measured mechanically. Furthermore, the prototype was tested by a user and body mechanics measured in gait analysis for varying walking speed, comparing the prototype to the original foot model. The results confirm speed dependent stiffness introduced by the novel device.Innblásturinn að þessari rannsókn er náttúrulegur breytileiki í stífni líffræðilegs ökkla við mismunandi hreyfingu. Markmiðið er að ná fram breytilegri stífni gervifótar í svörun við álagi með virkum efniseiginleikum snjallefna. Þessi ritgerð lýsir hönnun og gerð frumgerðar á kúplingu sem nýtir sérstaka skerþykkjandi efniseiginleika vökva (e. shear thickening fluids) sem felast í skyndilegri, ósamfelldri breytingu á seigju vökvans. Hraðaháð stífni næst með kerfi af hlið- og raðtengdri fjöðrun, þar sem kúplingin er notuð við yfirfærslu krafta í kerfinu. Þekkt hönnun á gervifæti er endurbætt með kúplingu sem breytir virkni fótarins. Stífni fótarins veltur þannig á hraða hreyfingar notandans, allt frá því að veita dempandi stuðning á mjög hægum gönguhraða, að því að veita fjaðrandi endurgjöf á venjulegum gönguhraða. Mikilvægt markmið í hönnun gervifóta er að hámarka orkunýtni þeirra. Markmiðið þessarar vinnu er að hanna gervifót sem veitir mjúkan stuðning við hægar hreyfingar, án þess að fórna þeirri orkunýtni sem hjálpar notandanum í venjulegri göngu. Virkni gervifótarins var greind með einingaraðferð (e. FEM) til að greina breytur og stærðir sem notaðar eru í endurbættu hönnunina. Kúplingin var þróuð og eiginleikar hennar staðfestir með prófunum. Frumgerð gervifótar var hönnuð og smíðuð, og hraðaháð stífni mæld. Ennfremur voru framkvæmdar notendaprófanir og göngugreining á mismunandi gönguhraða þar sem frumgerðin var borin saman við upprunalega gervifótinn. Niðurstöður prófana staðfestu hraðaháða stífni nýrrar hönnunar.This work was funded by the Technology Development Fund (grant no. 163805-0613) and the University of Iceland Research Fund