3D printed pneumatic soft actuators and sensors: their modeling, performance quantification, control and applications in soft robotic systems

Continued technological progress in robotic systems has led to more applications where robots and humans operate in close proximity and even physical contact in some cases. Soft robots, which are primarily made of highly compliant and deformable materials, provide inherently safe features, unlike conventional robots that are made of stiff and rigid components. These robots are ideal for interacting safely with humans and operating in highly dynamic environments. Soft robotics is a rapidly developing field exploiting biomimetic design principles, novel sensor and actuation concepts, and advanced manufacturing techniques. This work presents novel soft pneumatic actuators and sensors that are directly 3D printed in one manufacturing step without requiring postprocessing and support materials using low-cost and open-source fused deposition modeling (FDM) 3D printers that employ an off-the-shelf commercially available soft thermoplastic poly(urethane) (TPU). The performance of the soft actuators and sensors developed is optimized and predicted using finite element modeling (FEM) analytical models in some cases. A hyperelastic material model is developed for the TPU based on its experimental stress-strain data for use in FEM analysis. The novel soft vacuum bending (SOVA) and linear (LSOVA) actuators reported can be used in diverse robotic applications including locomotion robots, adaptive grippers, parallel manipulators, artificial muscles, modular robots, prosthetic hands, and prosthetic fingers. Also, the novel soft pneumatic sensing chambers (SPSC) developed can be used in diverse interactive human-machine interfaces including wearable gloves for virtual reality applications and controllers for soft adaptive grippers, soft push buttons for science, technology, engineering, and mathematics (STEM) education platforms, haptic feedback devices for rehabilitation, game controllers and throttle controllers for gaming and bending sensors for soft prosthetic hands. These SPSCs are directly 3D printed and embedded in a monolithic soft robotic finger as position and touch sensors for real-time position and force control. One of the aims of soft robotics is to design and fabricate robotic systems with a monolithic topology embedded with its actuators and sensors such that they can safely interact with their immediate physical environment. The results and conclusions of this thesis have significantly contributed to the realization of this aim

Development of an Upper Limb Myoelectric Prothesis in Flexible/Hybrid Material, for Application in Young Patients

With the recent developments in the Additive Manufacturing (AM) industry, new methods of prostheses production have taken over the prosthetic industry. These new prostheses models produced using 3-Dimensional (3D)-printing methods solve some of the issues of the most common prostheses, such as cost and weight, but, despite their growth, still present high rejection rates, especially in children. These rejections are mostly related to the low levels of anthropomorphism and limitations in terms of functionality associated to 3D printed prostheses. The main goal of this study was to develop an aesthetically appealing 3D printed myoelectric prosthesis for a four year old child with a transverse metacarpal total deficiency. The development of the prosthesis was based on the assessment and improvement of current 3D printable prosthetic models, and the integration of a myoelectric classifier and the electronic components into the model. The whole prosthesis was designed using a combination of the Fusion 360 CAD and SolidWorks CAD 2021 softwares, and produced using The Original Prusa i3 MK3S with polyactic acid (PLA) or Filaflex filaments. The prosthesis was designed through an iterative process, where several prototypes were developed in order to optimise its appearance and functionality. Some printed models were subjected to pull tests, that evaluated its flexibility and allowed the development of the electronic sector of the prosthesis. The developed prosthesis possessed a high level of anthropomorphism and functionality, consisting of a solution that is quite similar to the human hand and was able to simulate the intended movements, although with some limitations. Additionally, the device was relatively cheap and light when compared to existing 3D-printed myoelectric prostheses. Although this thesis has some limitations, it certainly contributed to clarify many of the doubts that still exist in the scientific community. Hopefully, it will help to further develop the prosthetic industry.Nos últimos anos, o desenvolvimento de técnicas de Manufactura Aditiva (MA) tem permitido a evolução nos métodos de produção de próteses. Esses novos modelos de próteses produzidos usando métodos de impressão 3D resolvem alguns dos problemas das próteses mais comuns no mercado, como custo e peso, mas, apesar destes avanços, ainda apresenta altas taxas de rejeição, principalmente em crianças. Essas taxas de rejeição estão muitas vezes relacionadas com os baixos níveis de antropomorfismo e funcionalidade destes modelos. O principal objetivo deste estudo tornou-se então desenvolver uma prótese mioelétrica esteticamente atraente, produzida através de impressão 3D, para ima criança de quatro anos e com deficiência total do metacarpo transverso. O desenvolvimento da prótese deu-se por meio da avaliação do modelos atuais de próteses produzidos por impressão 3D, melhoria das suas características e integração de um classificador mioeletrico e os componentes eletrônicos associados. A prótese foi toda projetada usando uma combinação dos softwares Fusion 360 CAD e SolidWorks CAD 2021 e produzido utilizando a The Original Prusa i3 MK3S e filamentos de PLA ou Filaflex. A prótese foi concebida através de um processo iterativo, onde vários protótipos foram desenvolvidos de forma a otimizar a sua aparência e funcionalidade. Alguns dos modelos impressos foram submetidos a testes de tração, de forma a avaliar a sua flexiblidade e desenvolver as componentes eletrónicas da prótese. A prótese desenvolvida possuía um alto nível de antropomorfismo e funcionalidade, obtendo-se uma solução bastante semelhante à mão humana capaz de simular, embora com algumas limitações, os movimentos pretendidos. Além disso, o dispositivo é relativamente barato e leve quando comparado com outros modelos de próteses produzidos por impressão 3D. Embora o protótipo final tenha algumas limitações, certamente contribui para o desenvolvimento do modelo prótetico e esclarece alguns dos problemas em modelos antigos. Espera-se que este estudo ajude a aprofundar e desenvolver a indústria das próteses

Design and Fabrication of Soft 3D Printed Actuators: Expanding Soft Robotics Applications

Soft pneumatic actuators are ideal for soft robotic applications due to their innate compliance and high power-weight ratios. Presently, the majority of soft pneumatic actuators are used to create bending motions, with very few able to produce significant linear movements. Fewer can actively produce strains in multiple directions. The further development of these actuators is limited by their fabrication methods, specifically the lack of suitable stretchable materials for 3D printing. In this thesis, a new highly elastic resin for digital light projection 3D printers, designated ElastAMBER, is developed and evaluated, which shows improvements over previously synthesised elastic resins. It is prepared from a di-functional polyether urethane acrylate oligomer and a blend of two different diluent monomers. ElastAMBER exhibits a viscosity of 1000 mPa.s at 40 °C, allowing easy printing at near room temperatures. The 3D-printed components present an elastomeric behaviour with a maximum extension ratio of 4.02 ± 0.06, an ultimate tensile strength of (1.23 ± 0.09) MPa, low hysteresis, and negligible viscoelastic relaxation

InMoov-robotin käsivarsien toteutus

Tiivistelmä. Erilaisia robotteja on käytetty jo kauan aikaa. Ensimmäiset robotit tehtiin teolliseen käyttöön, suurimmaksi osaksi liukuhihnatyöhön. Tällaisten robottien ei tarvitse mukautua ympäristöönsä, vaan ympäristö on rakennettu robotin ympärille. Robotiikan ja tekoälyn kehittyessä mahdollistuu myös täysin uudenlaisten robottien valmistus. Robotit voivat mukautua ympäristöönsä paremmin erilaisia sensoreita hyödyntäen. Nykyään robotteja käytetään monenlaiseen tarkoitukseen lääketieteestä autonomisiin autoihin. Robotit voivat olla kalliita suunnitella ja rakentaa, mutta 3d-tulostuksen mahdollistaman halvemman hinnan kautta myös tavallisilla ihmisillä on mahdollista kehittää protyyppejä. Tässä opinnäytetyössä keskitytään robotin rakentamiseen ja kokeiluun, sekä näissä nopean ja edullisen prototyyppien valmistuksen mahdollisuuksiin sekä ongelmiin. Työssä käytetään pohjana InMoov-robotin valmiita 3d-malleja ja Robot Operating System 2 -kirjastoa robotin ohjaamiseen. Näillä malleilla rakennetaan robotin kädet ja ne liitetään jo olemassa olevaan robottiin. Siinä kerrotaan miten servoa voidaan muokata, ja kuinka hammasrattaiden käyttöä voidaan hyödyntää robotin käsien liikuttamiseen. Verrattuna kaupallisiin robotteihin laadussa on eroja, mutta työn tarkoitus on olla esimerkkinä ja tukena muille, jotka haluavat kokeilla rakentaa robotin prototyyppiä edullisesti. 3d-tulostus mahdollistaa uusien osien tulostamisen helposti ja rikkinäiset osat voidaan vaihtaa. Keskeisiä ongelmia robotin rakentamisessa ovat mekaanisten osien heikkous, huonosti toteutetut johdotukset sekä sekava ohjelmistopuoli. Parannus- ja ratkaisuehdotuksia, toteutettuja ratkaisuja, sekä huomioitavia ja vältettäviä asioita esitetään työssä ja lisäksi pohditaan mahdollisia jatkotutkimuskohteita

Design and development of an ultra-low-cost electro - resistive band based myo activated prosthetic upper limb

In developing countries, many amputees have no access to the prosthesis. This is due to the challenges of the environment they are living in and to the prohibitive costs of available prostheses. To reduce this gap, a new concept design for an extremely low cost but highly functional upper limb prosthesis is presented. This goal is attained using a low-cost embedded platform (Arduino) and a wearable stretch-sensor adapted from Electro resistive bands (ERBs). In the proposed design, a sensor based on ERB is used to detect residual muscle contraction which detects the volumetric shifts of contraction instead of electromyography signals. The signals received via this sensor is then processed via an Arduino micro-controller to drive a single DC servo motor. The DC servo motor is directly geared onto a claw-style two-fingered prosthesis which is printed in-house from PLA plastic using a standard 3-D printer. The amount of closure of the prosthesis is fed-back to the user via a second ERB sensor directly connected to the claw in the form of haptic feedback. To make the design easier to maintain, the gears and mechanical parts are made so simple that can be crafted even from recovered materials. The entire design of prosthesis is presented in this thesis. The overall cost for the proposed prosthesis is estimated to be AUD 29. The proposed design can be easily scaled up to accommodate more complex designs such as having multiple individual fingers or wrist rotation

Piezoresistive Sensing in Additively Manufactured Prosthetics

This paper attempts to determine whether hobbyist 3D printers can be used to advance prosthetic capabilities. We attempt to answer this by designing, printing, and testing a prosthetic hand using a hobbyist 3D printer and hobbyist materials. The prosthetic hand with an opposable thumb was drafted from scratch and 3D printed collectively across four different fused deposition modeling printers; A Craftbot Plus Pro, CR-10, Jgaurora, and Qidi X-Plus. Once assembled, a material study was conducted against three different materials to identify the plausibility of sensing force using the materials piezoresistivity. Piezoresistivity is a measurement of resistance when a mechanical strain is applied. It was concluded that touch sensing capabilities could be utilized with 3D printed materials while on a hobbyist grade 3D printer. None of the materials required a heated chamber however, the argument of a heated bed improving the printability is undeniable. The likelihood of successfully incorporating this function into a 3D printed prosthetic had immense potential and promise

Osseointegration for Amputees: Past, Present and Future: Basic Science, Innovations in Surgical Technique, Implant Design and Rehabilitation Strategies

Loss of a leg or arm is a tremendous disability. Immediate and obvious impairments are decreased mobility or diminished functional capacity. Not quite as obvious are the difficulties associated with activities of daily living, quality of life impairments, sometimes loss of independence or employment, and the mental health issues which often accompany limb loss. The interface between native tissue and the prosthetic limb presents the greatest challenge to amputee rehabilitation. Computer-controlled robotic limbs have been widely available since the 1990s. However, the weight of prosthetic limbs, coupled with the difficulty of where to locate the components, requires substantial loads to be transferred through the humanimplant interface. This interface has always been a skin-squeezing mechanism which results in repetitive soft-tissue loading and trauma, in both compression and shear, which inevitably causes multiple problems (pain, skin breakdown and infection, hyperhidrosis, allergic reaction to the material) leading to periodic or prolonged prosthesis disuse. So unfortunately, despite all the effort and expense invested in the prosthetic limb itself, patients often were unable to benefit. Percutaneous EndoProsthetic Osseointegration for Limbs (PEPOL) is a revolutionary technique that involves anchoring a metal implant directly to a patient’s skeleton, then permanently passed through the patient’s skin, and attached to a prosthetic limb. By doing this, the weight of the prosthesis is borne by the patient’s skeleton and is directly powered by muscles, leading to a lighter and more native experience. The skin is no longer compressed and traumatised, eliminating the aforementioned issues. Since learning about this technology in the mid-2000s and performing my first independent procedure in 2009, I have investigated and pioneered the world’s leading surgical techniques and rehabilitative methods for PEPOL. Treating nearly 1000 amputees via the Osseointegration Group of Australia and the MQ Health Limb Reconstruction Centre at Macquarie University has allowed research to be performed on this technology, documented, and discussed in the 2 Body of Work. Patients almost always improve their objective and assessed mobility performance (Overall 38.6% distance improvement on the 6MWT), they wear their prosthetic limb more (Overall 38.1% increase in the Q-TFA Prosthetic Use Score), and they are subjectively more satisfied with their condition as an amputee (Overall 41.1% increase in the Q-TFA Global Score) . While these benefits are consistent, my research has also identified the fortunately limited problems with infection and soft tissue management (29% of all patients required re-operations due to direct or indirect complications). PEPOL clearly provides excellent improvement for the vast majority of patients, and the continued investigation of this technology should lead to even greater improvements in progressing from what is already successful, make it more readily available, and ameliorate its existing challenges

Low cost digital fabrication approach for thumb orthoses

[EN] Purpose - The purpose of this paper is to describe a novel design workflow for the digital fabrication of custom- made orthoses (CMIO). It is intended to provide an easier process for clinical practitioners and orthotic technicians alike. It further functions to reduce the dependency of the operators' abilities and skills. Design/methodology/approach - The technical assessment covers low-cost three-dimensional (3D) scanning, free computer-aided design (CAD) software, and desktop 3D printing and acetone vapour finishing. To analyse its viability, a cost comparison was carried out between the proposed workflow and the traditional CMIO manufacture method. Findings - The results show that the proposed workflow is a technically feasible and cost-effective solution to improve upon the traditional process of design and manufacture of custom- made static trapeziometacarpal (TMC) orthoses. Further studies are needed for ensuring a clinically feasible approach and for estimating the efficacy of the method for the recovery process in patients. Social implications - The feasibility of the process increases the impact of the study, as the great accessibility to this type of 3D printers makes the digital fabrication method easier to be adopted by operators. Originality/value - Although some research has been conducted on digital fabrication of CMIO, few studies have investigated the use of desktop 3D printing in any systematic way. This study provides a first step in the exploration of a new design workflow using low-cost digital fabrication tools combined with non-manual finishing.Fernandez-Vicente, M.; Escario Chust, A.; Conejero Rodilla, A. (2017). Low cost digital fabrication approach for thumb orthoses. Rapid Prototyping Journal. 23(6):1020-1031. doi:10.1108/RPJ-12-2015-0187S1020103123