Non-linear actuators and simulation tools for rehabilitation devices

Mención Internacional en el título de doctorRehabilitation robotics is a field of research that investigates the applications of robotics in motor function therapy for recovering the motor control and motor capability. In general, this type of rehabilitation has been found effective in therapy for persons suffering motor disorders, especially due to stroke or spinal cord injuries. This type of devices generally are well tolerated by the patients also being a motivation in rehabilitation therapy. In the last years the rehabilitation robotics has become more popular, capturing the attention at various research centers. They focused on the development more effective devices in rehabilitation therapy, with a higher acceptance factor of patients tacking into account: the financial cost, weight and comfort of the device. Among the rehabilitation devices, an important category is represented by the rehabilitation exoskeletons, which in addition to the human skeletons help to protect and support the external human body. This became more popular between the rehabilitation devices due to the easily adapting with the dynamics of human body, possibility to use them such as wearable devices and low weight and dimensions which permit easy transportation. Nowadays, in the development of any robotic device the simulation tools play an important role due to their capacity to analyse the expected performance of the system designed prior to manufacture. In the development of the rehabilitation devices, the biomechanical software which is capable to simulate the behaviour interaction between the human body and the robotics devices, play an important role. This helps to choose suitable actuators for the rehabilitation device, to evaluate possible mechanical designs, and to analyse the necessary controls algorithms before being tested in real systems. This thesis presents a research proposing an alternative solution for the current systems of actuation on the exoskeletons for robotic rehabilitation. The proposed solution, has a direct impact, improving issues like device weight, noise, fabrication costs, size an patient comfort. In order to reach the desired results, a biomechanical software based on Biomechanics of Bodies (BoB) simulator where the behaviour of the human body and the rehabilitation device with his actuators can be analysed, was developed. In the context of the main objective of this research, a series of actuators have been analysed, including solutions between the non-linear actuation systems. Between these systems, two solutions have been analysed in detail: ultrasonic motors and Shape Memory Alloy material. Due to the force - weight characteristics of each device (in simulation with the human body), the Shape Memory Alloy material was chosen as principal actuator candidate for rehabilitation devices. The proposed control algorithm for the actuators based on Shape Memory Alloy, was tested over various configurations of actuators design and analysed in terms of energy eficiency, cooling deformation and movement. For the bioinspirated movements, such as the muscular group's biceps-triceps, a control algorithm capable to control two Shape Memory Alloy based actuators in antagonistic movement, has been developed. A segmented exoskeleton based on Shape Memory Alloy actuators for the upper limb evaluation and rehabilitation therapy was proposed to demosntrate the eligibility of the actuation system. This is divided in individual rehabilitation devices for the shoulder, elbow and wrist. The results of this research was tested and validated in the real elbow exoskeleton with two degrees of freedom developed during this thesis.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Eduardo Rocón de Lima.- Secretario: Concepción Alicia Monje Micharet.- Vocal: Martin Stoele

Hand-Exoskeleton Assisted Progressive Neurorehabilitation Using Impedance Adaptation Based Challenge Level Adjustment Method

This paper presents an underactuated design of a robotic hand exoskeleton, and a challenge based neurorehabilitation strategy. The exoskeleton is designed to reproduce natural human fingertip paths during extension and grasping, keeping minimal kinematic complexity. It facilitates an impedance adaptation based trigged assistance control strategy by switching between active non-assist and passive assistance modes. In the active non-assist mode, the exoskeleton motion follows the applied fingertip forces based on an impedance model. If the applied fingertip forces are inadequate, the passive assistance mode is triggered. The impedance parameters are updated at regular intervals based on the user performance, to implement a challenge based rehabilitation strategy. A six-week long hand therapy, conducted on four chronic stroke patients, resulted in significant (p-value <; 0.05) increase in force generation capacity and decrease (p-value <; 0.05) in the required assistance. Also, there was a significant (p-value <; 0.05) increase in the system impedance parameters which adequately challenged the patients. The change in the Action-Research-Arm-Test (ARAT) scores from baseline was also found to be significant (p-value <; 0.05) and beyond the minimal clinically important difference (MCID) limit. Thus, the results prove that the proposed control strategy with has the potential to be a clinically effective solution for personalized rehabilitation of poststroke hand functionality

Application and modelling of shape-memory alloys for structural vibration control : state-of-the-art review

One of the most essential components of structural design for civil engineers is to build a system that is resistant to environmental conditions such as harsh chemical environments, and catastrophic disasters like earthquakes and hurricanes. Under these circumstances and disturbances, conventional building materials such as steel and concrete may demonstrate inadequate performance in the form of corrosion, deterioration, oxidizing, etc. Shape Memory Alloys (SMAs) are novel metals with distinct features and desirable potential to overcome the inadequacies of existing construction materials and enable the structure to tolerate disturbances more efficiently. Shape Memory Effect (SME) and Pseudoelasticity (PE) have been the most attractive characteristics that scientists have focused on among the various features that SMAs exhibit. The SME enables the material to retain its original shape after severe deformation, whereas the PE behaviour of SMAs provides a wide range of deformation while mitigating a substantial amount of susceptible stresses. These behaviours are the consequence of the phase transformation between austenite and martensite. Many investigations on the modelling and application of SMAs in structural systems to endure applied dynamic loadings in the form of active, passive, and hybrid vibration control systems have been undertaken. The focus of this paper is to present an overview of the SMA-based applications and most frequently employed constitutive modelling, as well as their limits in structural vibration control and seismic isolation devices

Design of a shape memory alloy actuator for soft wearable robots

Soft robotics represents a paradigm shift in the design of conventional robots; while the latter are designed as monolithic structures, made of rigid materials and normally composed of several stiff joints, the design of soft robots is based on the use of deformable materials such as polymers, fluids or gels, resulting in a biomimetic design that replicates the behavior of organic tissues. The introduction of this design philosophy into the field of wearable robots has transformed them from rigid and cumbersome devices into something we could call exo-suits or exo-musculatures: motorized, lightweight and comfortable clothing-like devices. If one thinks of the ideal soft wearable robot (exoskeleton) as a piece of clothing in which the actuation system is fully integrated into its fabrics, we consider that that existing technologies currently used in the design of these devices do not fully satisfy this premise. Ultimately, these actuation systems are based on conventional technologies such as DC motors or pneumatic actuators, which due to their volume and weight, prevent a seamless integration into the structure of the soft exoskeleton. The aim of this thesis is, therefore, to design of an actuator that represents an alternative to the technologies currently used in the field of soft wearable robotics, after having determined the need for an actuator for soft exoskeletons that is compact, flexible and lightweight, while also being able to produce the force required to move the limbs of a human user. Since conventional actuation technologies do not allow the design of an actuator with the required characteristics, the proposed actuator design has been based on so-called emerging actuation technologies, more specifically, on shape memory alloys (SMA). The mechanical design of the actuator is based on the Bowden transmission system. The SMA wire used as the transducer of the actuator has been routed into a flexible sheath, which, in addition to being easily adaptable to the user's body, increases the actuation bandwidth by reducing the cooling time of the SMA element by 30 %. At its nominal operating regime, the actuator provides an output displacement of 24 mm and generates a force of 64 N. Along with the actuator, a thermomechanical model of its SMA transducer has been developed to simulate its complex behavior. The developed model is a useful tool in the design process of future SMA-based applications, accelerating development ix time and reducing costs. The model shows very few discrepancies with respect to the behavior of a real wire. In addition, the model simulates characteristic phenomena of these alloys such as thermal hysteresis, including internal hysteresis loops and returnpoint memory, the dependence between transformation temperatures and applied force, or the effects of latent heat of transformation on the wire heating and cooling processes. To control the actuator, the use of a non-linear control technique called four-term bilinear proportional-integral-derivative controller (BPID) is proposed. The BPID controller compensates the non-linear behavior of the actuator caused by the thermal hysteresis of the SMA. Compared to the operation of two other implemented controllers, the BPID controller offers a very stable and robust performance, minimizing steady-state errors and without the appearance of limit cycles or other effects associated with the control of these alloys. To demonstrate that the proposed actuator together with the BPID controller are a valid solution for implementing the actuation system of a soft exoskeleton, both developments have been integrated into a real soft hand exoskeleton, designed to provide force assistance to astronauts. In this case, in addition to using the BPID controller to control the position of the actuators, it has been applied to the control of the assistive force provided by the exoskeleton. Through a simple mechanical multiplication mechanism, the actuator generates a linear displacement of 54 mm and a force of 31 N, thus fulfilling the design requirements imposed by the application of the exoskeleton. Regarding the control of the device, the BPID controller is a valid control technique to control both the position and the force of a soft exoskeleton using an actuation system based on the actuator proposed in this thesis.La robótica flexible (soft robotics) ha supuesto un cambio de paradigma en el diseño de robots convencionales; mientras que estos consisten en estructuras monolíticas, hechas de materiales duros y normalmente compuestas de varias articulaciones rígidas, el diseño de los robots flexibles se basa en el uso de materiales deformables como polímeros, fluidos o geles, resultando en un diseño biomimético que replica el comportamiento de los tejidos orgánicos. La introducción de esta filosofía de diseño en el campo de los robots vestibles (wearable robots) ha hecho que estos pasen de ser dispositivos rígidos y pesados a ser algo que podríamos llamar exo-trajes o exo-musculaturas: prendas de vestir motorizadas, ligeras y cómodas. Si se piensa en el robot vestible (exoesqueleto) flexible ideal como una prenda de vestir en la que el sistema de actuación está totalmente integrado en sus tejidos, consideramos que las tecnologías existentes que se utilizan actualmente en el diseño de estos dispositivos no satisfacen plenamente esta premisa. En última instancia, estos sistemas de actuaci on se basan en tecnologías convencionales como los motores de corriente continua o los actuadores neumáticos, que debido a su volumen y peso, hacen imposible una integraci on completa en la estructura del exoesqueleto flexible. El objetivo de esta tesis es, por tanto, el diseño de un actuador que suponga una alternativa a las tecnologias actualmente utilizadas en el campo de los exoesqueletos flexibles, tras haber determinado la necesidad de un actuador para estos dispositivos que sea compacto, flexible y ligero, y que al mismo tiempo sea capaz de producir la fuerza necesaria para mover las extremidades de un usuario humano. Dado que las tecnologías de actuación convencionales no permiten diseñar un actuador de las características necesarias, se ha optado por basar el diseño del actuador propuesto en las llamadas tecnologías de actuación emergentes, en concreto, en las aleaciones con memoria de forma (SMA). El diseño mecánico del actuador está basado en el sistema de transmisión Bowden. El hilo de SMA usado como transductor del actuador se ha introducido en una funda flexible que, además de adaptarse facilmente al cuerpo del usuario, aumenta el ancho de banda de actuación al reducir un 30 % el tiempo de enfriamiento del elemento SMA. En su régimen nominal de operaci on, el actuador proporciona un desplazamiento de salida de 24 mm y genera una fuerza de 64 N. Además del actuador, se ha desarrollado un modelo termomecánico de su transductor SMA que permite simular su complejo comportamiento. El modelo desarrollado es una herramienta útil en el proceso de diseño de futuras aplicaciones basadas en SMA, acelerando el tiempo de desarrollo y reduciendo costes. El modelo muestra muy pocas discrepancias con respecto al comportamiento de un hilo real. Además, es capaz de simular fenómenos característicos de estas aleaciones como la histéresis térmica, incluyendo los bucles internos de histéresis y la memoria de puntos de retorno (return-point memory), la dependencia entre las temperaturas de transformacion y la fuerza aplicada, o los efectos del calor latente de transformación en el calentamiento y el enfriamiento del hilo. Para controlar el actuador, se propone el uso de una t ecnica de control no lineal llamada controlador proporcional-integral-derivativo bilineal de cuatro términos (BPID). El controlador BPID compensa el comportamiento no lineal del actuador causado por la histéresis térmica del SMA. Comparado con el funcionamiento de otros dos controladores implementados, el controlador BPID ofrece un rendimiento muy estable y robusto, minimizando el error de estado estacionario y sin la aparición de ciclos límite u otros efectos asociados al control de estas aleaciones. Para demostrar que el actuador propuesto junto con el controlador BPID son una soluci on válida para implementar el sistema de actuación de un exoesqueleto flexible, se han integrado ambos desarrollos en un exoesqueleto flexible de mano real, diseñado para proporcionar asistencia de fuerza a astronautas. En este caso, además de utilizar el controlador BPID para controlar la posición de los actuadores, se ha aplicado al control de la fuerza proporcionada por el exoesqueleto. Mediante un simple mecanismo de multiplicación mecánica, el actuador genera un desplazamiento lineal de 54 mm y una fuerza de 31 N, cumpliendo así con los requisitos de diseño impuestos por la aplicación del exoesqueleto. Respecto al control del dispositivo, el controlador BPID es una técnica de control válida para controlar tanto la posición como la fuerza de un exoesqueleto flexible que use un sistema de actuación basado en el actuador propuesto en esta tesis.Programa de Doctorado en Ingeniería Eléctrica, Electrónica y Automática por la Universidad Carlos III de MadridPresidente: Fabio Bonsignorio.- Secretario: Concepción Alicia Monje Micharet.- Vocal: Elena García Armad

A Methodology Towards Comprehensive Evaluation of Shape Memory Alloy Actuators for Prosthetic Finger Design

Presently, DC motors are the actuator of choice within intelligent upper limb prostheses. However, the weight and dimensions associated with suitable DC motors are not always compatible with the geometric restrictions of a prosthetic hand; reducing available degrees of freedom and ultimately rendering the prosthesis uncomfortable for the end-user. As a result, the search is on-going to find a more appropriate actuation solution that is lightweight, noiseless, strong and cheap. Shape memory alloy (SMA) actuators offer the potential to meet these requirements. To date, no viable upper limb prosthesis using SMA actuators has been developed. The primary reasons lie in low force generation as a result of unsuitable actuator designs, and significant difficulties in control owing to the highly nonlinear response of SMAs when subjected to joule heating. This work presents a novel and comprehensive methodology to facilitate evaluation of SMA bundle actuators for prosthetic finger design. SMA bundle actuators feature multiple SMA wires in parallel. This allows for increased force generation without compromising on dynamic performance. The SMA bundle actuator is tasked with reproducing the typical forces and contractions associated with the human finger in a prosthetic finger design, whilst maintaining a high degree of energy efficiency. A novel approach to SMA control is employed, whereby an adaptive controller is developed and tuned using the underlying thermo-mechanical principles of operation of SMA wires. A mathematical simulation of the kinematics and dynamics of motion provides a platform for designing, optimizing and evaluating suitable SMA bundle actuators offline. This significantly reduces the time and cost involved in implementing an appropriate actuation solution. Experimental results show iii that the performance of SMA bundle actuators is favourable for prosthesis applications. Phalangeal tip forces are shown to improve significantly through bundling of SMA wire actuators, while dynamic performance is maintained owing to the design and implementation of the selected control strategy. The work is intended to serve as a roadmap for fellow researchers seeking to design, implement and control SMA bundle actuators in a prosthesis design. Furthermore, the methodology can also be adopted to serve as a guide in the evaluation of other non-conventional actuation technologies in alternative applications

Modeling, Analysis, Force Sensing and Control of Continuum Robots for Minimally Invasive Surgery

This dissertation describes design, modeling and application of continuum robotics for surgical applications, specifically parallel continuum robots (PCRs) and concentric tube manipulators (CTMs). The introduction of robotics into surgical applications has allowed for a greater degree of precision, less invasive access to more remote surgical sites, and user-intuitive interfaces with enhanced vision systems. The most recent developments have been in the space of continuum robots, whose exible structure create an inherent safety factor when in contact with fragile tissues. The design challenges that exist involve balancing size and strength of the manipulators, controlling the manipulators over long transmission pathways, and incorporating force sensing and feedback from the manipulators to the user. Contributions presented in this work include: (1) prototyping, design, force sensing, and force control investigations of PCRs, and (2) prototyping of a concentric tube manipulator for use in a standard colonoscope. A general kinetostatic model is presented for PCRs along with identification of multiple physical constraints encountered in design and construction. Design considerations and manipulator capabilities are examined in the form of matrix metrics and ellipsoid representations. Finally, force sensing and control are explored and experimental results are provided showing the accuracy of force estimates based on actuation force measurements and control capabilities. An overview of the design requirements, manipulator construction, analysis and experimental results are provided for a CTM used as a tool manipulator in a traditional colonoscope. Currently, tools used in colonoscopic procedures are straight and exit the front of the scope with 1 DOF of operation (jaws of a grasper, tightening of a loop, etc.). This research shows that with a CTM deployed, the dexterity of these tools can be increased dramatically, increasing accuracy of tool operation, ease of use and safety of the overall procedure. The prototype investigated in this work allows for multiple tools to be used during a single procedure. Experimental results show the feasibility and advantages of the newly-designed manipulators

Design, Modeling and Control of Micro-scale and Meso-scale Tendon-Driven Surgical Robots

Manual manipulation of passive surgical tools is time consuming with uncertain results in cases of navigating tortuous anatomy, avoiding critical anatomical landmarks, and reaching targets not located in the linear range of these tools. For example, in many cardiovascular procedures, manual navigation of a micro-scale passive guidewire results in increased procedure times and radiation exposure. This thesis introduces the design of two steerable guidewires: 1) A two degree-of-freedom (2-DoF) robotic guidewire with orthogonally oriented joints to access points in a three dimensional workspace, and 2) a micro-scale coaxially aligned steerable (COAST) guidewire robot that demonstrates variable and independently controlled bending length and curvature of the distal end. The 2-DoF guidewire features two micromachined joints from a tube of superelastic nitinol of outer diameter 0.78 mm. Each joint is actuated with two nitinol tendons. The joints that are used in this robot are called bidirectional asymmetric notch (BAN) joints, and the advantages of these joints are explored and analyzed. The design of the COAST robotic guidewire involves three coaxially aligned tubes with a single tendon running centrally through the length of the robot. The outer tubes are made from micromachined nitinol allowing for tendon-driven bending of the robot at variable bending curvatures, while an inner stainless steel tube controls the bending length of the robot. By varying the lengths of the tubes as well as the tendon, and by insertion and retraction of the entire assembly, various joint lengths and curvatures may be achieved. Kinematic and static models, a compact actuation system, and a controller for this robot are presented. The capability of the robot to accurately navigate through phantom anatomical bifurcations and tortuous angles is also demonstrated in three dimensional phantom vasculature. At the meso-scale, manual navigation of passive pediatric neuroendoscopes for endoscopic third ventriculostomy may not reach target locations in the patient's ventricle. This work introduces the design, analysis and control of a meso-scale two degree-of-freedom robotic bipolar electrocautery tool that increases the workspace of the neurosurgeon. A static model is proposed for the robot joints that avoids problems arising from pure kinematic control. Using this model, a control system is developed that comprises of a disturbance observer to provide precise force control and compensate for joint hysteresis. A handheld controller is developed and demonstrated in this thesis. To allow the clinician to estimate the shape of the steerable tools within the anatomy for both micro-scale and meso-scale tools, a miniature tendon force sensor and a high deflection shape sensor are proposed and demonstrated. The force sensor features a compact design consisting of a single LED, dual-phototransistor, and a dual-screen arrangement to increase the linear range of sensor output and compensate for external disturbances, thereby allowing force measurement of up to 21 N with 99.58 % accuracy. The shape sensor uses fiber Bragg grating based optical cable mounted on a micromachined tube and is capable of measuring curvatures as high as 145 /m. These sensors were incorporated and tested in the guidewire and the neuroendoscope tool robots and can provide robust feedback for closed-loop control of these devices in the future.Ph.D

Design and development of an internal bone distractor activated by a shape memory material

Dissertação de mestrado integrado em Biomedical Engineering (área de especialização em Biomaterials, Rehabilitation and Biomechanics)The mandible, also known as the lower jaw, is the largest and strongest bone in the human skull. Maxillary and mandibular anomalies constitute a significant portion of craniofacial anomalies. Mandibular deficiency may be developmental, as in the case of hemifacial microsomia (1 in 3500 live births) and syndromes like Goldenhar syndrome or Treacher Collins syndrome (1 in every 25,000 births), or acquired due to early loss of dentition, trauma (e.g., fractures), cancer and temporomandibular joint ankylosis. The correction of maxillofacial deformities can be performed through conventional orthognathic surgeries, sometimes requiring bone grafts or, more recently, through distraction osteogenesis (DO). The DO technique is based on the principle of “tension-stress” and is defined as a biological process of new bone formation between two surfaces of bone segments that are gradually separated due to traction force induced by a distraction device. Although DO is an advantageous process, bone distractors currently available have some associated complications (e.g., infection, nerve and tooth injury, scarring, open bite, relapse, device failure and pin/screw loosening) and limitations (e.g., aesthetically unappealing and the inability of internal devices to alter the direction of the distraction vector). Taking all this into account, the possibility of improving the mandibular osteogenic distraction devices is noteworthy. The development of the present project is divided into several stages, from the identification of areas for improvement and the creation of a set of concepts to the selection of the final concepts. With the input of Doctor Alberto Pereira, who holds positions such as Head of Facial Reconstructive Surgery unit at Luz Lisbon Hospital and Chair of the AOCMF Foundation distraction taskforce, were identified areas for improvement and the requirements and objectives that the new concept should accomplish were defined. The concepts of the medical device were modulated with a CAD program to allow a clear comprehension of the respective functionality. The final selected concepts aim to overcome most of the complications currently observed and they allow for distraction vector adjustments during the activation phase in order to obtain the best possible results in terms of facial symmetry. Additionally, both concepts have an innovative activation mechanism composed of shape memory materials. The activation mechanism of the two concepts is slightly different, however, the principle of operation is the same. In this sense, the present medical device aims to have the ability to improve the quality of medical treatment and to eliminate the aesthetic issues with the device being completely internal and practically imperceptible.A mandíbula, também conhecida como maxilar inferior, é o maior e mais forte osso do crânio humano. As anomalias maxilares e mandibulares constituem uma percentagem significativa das anomalias craniofaciais. A deficiência mandibular pode ser de desenvolvimento, como no caso de microssomia hemifacial (1 em 3500) e síndromes como a síndrome de Treacher Collins (1 em 25000), ou adquirida devido à perda precoce da dentição, fraturas, cancro e anquilose da articulação temporomandibular. A correção das deformidades maxilofaciais pode ser realizada por meio de cirurgias ortognáticas convencionais, algumas vezes necessitando enxertos ósseos ou, mais recentemente, por distração osteogénica (DO). A técnica de DO é baseada no princípio de “tension-stress” e é definida como um processo biológico de neoformação óssea entre duas superfícies de segmentos ósseos que se vão separando gradualmente devido a uma força de tração induzida por um dispositivo de distração. Embora a DO seja um processo vantajoso, os distratores ósseos atualmente disponíveis originam algumas complicações (p. ex., infeção, lesão do nevo e dente, cicatrizes, mordida aberta, recidiva, falha do dispositivo e ‘desapertar/soltar’ dos pinos/parafuso) e possuem limitações associadas (p. ex., questões estéticas e a incapacidade dos dispositivos internos de alterar a direção do vetor de distração). Tendo tudo isso em consideração, a possibilidade de aprimoramento dos dispositivos de DO mandibular é notória. O desenvolvimento do presente projeto está dividido em várias etapas, desde a identificação das áreas de melhoria, a criação de um conjunto de conceitos e a seleção dos conceitos finais. Com a colaboração do Dr. Alberto Pereira, que exerce funções como Chefe da Unidade de Cirurgia Reconstrutiva Facial do Hospital Luz Lisboa e Presidente do Grupo de Trabalho de Distração da Fundação AOCMF, foram identificadas áreas de melhoria e foram definidos os requisitos e objetivos que o novo dispositivo deveria cumprir. Os conceitos foram modulados com um programa CAD para permitir uma compreensão clara dos elementos, mecanismos e do respetivo funcionamento. Os conceitos selecionados visam superar grande parte das complicações observadas e permitem ajustes do vetor de distração durante a fase de ativação, de forma a obter os melhores resultados possíveis em termos de simetria facial. Além disso, ambos os conceitos possuem um inovador mecanismo de ativação composto por materiais com memória de forma. O mecanismo de ativação difere ligeiramente entre os dois conceitos, porém o princípio de funcionamento é o mesmo. O presente dispositivo médico visa ter a capacidade de melhorar a qualidade do tratamento e eliminar totalmente os problemas estéticos, sendo um dispositivo totalmente interno e praticamente impercetível

Development of soft modular robotics

This thesis covers the development and validation of soft robots in providing upper limb assistive motion. The main purpose of this research is to develop highly compliant and resilient actuators that generate motion for elbow and shoulder movements. To accomplish the purpose of the study, the fabrication, geometric construction along with experimental data of pressure, torque and range of motion of all developed actuators are described. The main contribution of this thesis is the development of soft actuators that transfer force via elastic deformation in order to generate assistive motion; features such as flexibility and soft contact with the skin ensure excellent safety potential of the actuators. To reduce the instability phenomenon attributed to the elastic response of rubber under large deformations that leads to bulging, the implementation of a pleated network design and embedded braided mesh network is presented. Bulging was reduced and torque output was increased with the integration of braided mesh into the silicone rubber actuator. The soft actuators developed for elbow and shoulder motion was tested on ten healthy participants thereby demonstrating its comfort, ease of use, fitting and removal as well as its practicality as an assistive apparatus for stroke patients. The use of soft robotics to provide shoulder motion was also assessed by the integration of soft robotics with a gravity compensated exoskeleton. The developed soft actuators were powered with electro-pneumatic hardware components presented in a compact, embedded form. Positive and negative air pressure control was implemented by a piecewise linear control algorithm with the performance of the controller shown. The design of a novel muscle made entirely of silicone rubber that contract upon actuation was described together with the manufacturing procedure, design parameters and measurement results of performance of these muscles such as the velocity of shortening, isometric contraction and maximal obtainable muscle force (without shortening). The muscles are manufactured to mimic the skeletal muscles present in the human body. These muscles are composed of a number of wedge-like units in series, the number of these wedge units increase the contraction. The soft muscles were characterized in order to find optimum design parameters that results in more contraction and speed; the muscles were tested on a model hinge joint to execute flexion/extension of the forearm at the elbow. Aside from contracting, the muscle has an interesting capability of producing bidirectional bending by the regulation of internal positive and negative air pressure in each wedge unit. In order to measure performance data relating to range of motion from bending, rotary and muscle actuators, computer vision processing was made use of. Soft robots are made with materials that experience large deformations, the sensors used to obtain measurement data can either be through the use of embedded sensors or visual processing. The use of embedded sensors can be cumbersome, resulting in limitation of its performance. The visual processing algorithms implemented to measure performance data such as angle of motion, bending angle and contraction ratio in real-time using a Webcam is described. Visual processing concepts such as colour tracking, template matching, camera calibration were applied. The developed vision system was applied to execute vision based motion control which is able to move the soft robot to a desired position using high level vision control and lower level pressure control. The material described in the preceding paragraphs are presented in an interrelated format. A concise introduction to the thesis is presented in the first chapter. An extensive survey of the field of soft robotics including materials, manufacturing procedure, actuation principles, primary accomplishments, control and challenges are presented in the literature review chapter, together with a review of rehabilitation devices. Since this work focused on the use of silicone rubber as actuator material, a brief introduction to working with silicone rubber as an engineering material is presented in the third chapter. The conclusions of the work and suggestions for future research are provided at the last chapter of this thesis