The HydroBone is a variable stiffness load-bearing element, which utilizes jamming of granular media to achieve stiffness modulation, controlled by the application of positive pressure. Several compressive tests were conducted on the HydroBone in order to quantify the load-bearing capability of the system. It was determined that the stiffness of the HydroBone was a function of the internal pressure of the system. A controller was modeled based on this function to achieve automatic stiffness modulation of the HydroBone. An exoskeleton was designed based on the HydroBone and various actuators for the exoskeleton were considered. The HydroMuscle, a soft linear actuator was selected to provide knee actuation for the exoskeleton, based on several efficiency and force output test conducted. A knee brace was designed, capable of producing 15Nm of torque on the knee, actuated using Bowden cables coupled to the HydroMuscles.

Este trabalho consiste no projeto mecânico de um exoesqueleto robótico para paraplégicos com lesões medulares entre T2 a L1, ou seja, sem mobilidade da cintura para baixo e com mobilidade do peito para cima, inclusive das mãos. A utilização do equipamento necessita da utilização de muletas ou andadores. O mecanismo possui seis graus de liberdade, sendo quatro atuados por motorredutores (joelhos e quadris) e dois suportados por molas (tornozelos). Os motorredutores são projetados especialmente para o exoesqueleto, sendo compostos de um motor de corrente continua de imã permanente e um redutor harmônico do tipo panqueca acoplados de forma adequada para minimizar peso e volume. Para calcular os esforços solicitados em cada articulação foi desenvolvido um modelo dinâmico do corpo humano para simular os movimentos que o exoesqueleto é capaz de realizar, que são: marchar, sentar, levantar e subir e descer escadas. O modelo utilizado do corpo humano possui cinco ligamentos rígidos e é capaz de simular movimentos no plano vertical. Os resultados obtidos da simulação são comparados com resultados experimentais da literatura e são considerados satisfatórios. / This work presents a mechanical design of a robotic exoskeleton for paraplegics with spinal cord injuries between T2 to L1, that means, without mobility from the waist down and with mobility from the chest up, including the hands. For using the equipment the paraplegic needs the aid of crutches or walkers. The mechanism has six degrees of freedom, with four degrees actuated by gear motors (knees and hips), and two degrees supported by springs (ankles). The gear motors are designed especially for the exoskeleton. They are composed by an permanent magnet brushless electric motor conveniently coupled with an pancake harmonic speed reducer to minimize weight and volume. For calculating the efforts in each joint a model for the human body is developed to simulate the movements the exoskeleton can perform, which are: walk, sit, standup and climb up and down stairs. The human body model has five rigid links and it is capable to simulate movements in the vertical plane. The results obtained in the simulations are compared very well with experimental results from the literature.

A control method is proposed for exercising specific muscles of a human's lower body. This is accomplished using an exoskeleton that imposes active force feedback control. The proposed method involves a combined dynamic model of the musculoskeletal system of the lower-body with the dynamics of pneumatic actuators. The exoskeleton is designed to allow for individual control of mono-articular or bi-articular muscles to be exercised while not inhibiting the subject's range of motion. The control method has been implemented in a 1-Degree of Freedom (DOF) exoskeleton that is designed to resist the motion of the human knee by applying actuator forces in opposition to a specified muscle force profile. In this research, there is a discussion on the model of the human's lower body and how muscles are affected as a function of joint positions. Then it is discussed how to calculate for the forces needed by a pneumatic actuator to oppose the muscles to create the desired muscle force profile at a given joint angles. The proposed exoskeleton could be utilized either for rehabilitation purposes, to prevent muscle atrophy and bone loss of astronauts, or for muscle training in general.

abstract: The world population is aging. Age-related disorders such as stroke and spinal cord injury are increasing rapidly, and such patients often suffer from mobility impairment. Wearable robotic exoskeletons are developed that serve as rehabilitation devices for these patients. In this thesis, a knee exoskeleton design with higher torque output compared to the first version, is designed and fabricated. A series elastic actuator is one of the many actuation mechanisms employed in exoskeletons. In this mechanism a torsion spring is used between the actuator and human joint. It serves as torque sensor and energy buffer, making it compact and safe. A version of knee exoskeleton was developed using the SEA mechanism. It uses worm gear and spur gear combination to amplify the assistive torque generated from the DC motor. It weighs 1.57 kg and provides a maximum assistive torque of 11.26 N·m. It can be used as a rehabilitation device for patients affected with knee joint impairment. A new version of exoskeleton design is proposed as an improvement over the first version. It consists of components such as brushless DC motor and planetary gear that are selected to meet the design requirements and biomechanical considerations. All the other components such as bevel gear and torsion spring are selected to be compatible with the exoskeleton. The frame of the exoskeleton is modeled in SolidWorks to be modular and easy to assemble. It is fabricated using sheet metal aluminum. It is designed to provide a maximum assistive torque of 23 N·m, two times over the present exoskeleton. A simple brace is 3D printed, making it easy to wear and use. It weighs 2.4 kg. The exoskeleton is equipped with encoders that are used to measure spring deflection and motor angle. They act as sensors for precise control of the exoskeleton. An impedance-based control is implemented using NI MyRIO, a FPGA based controller. The motor is controlled using a motor driver and powered using an external battery source. The bench tests and walking tests are presented. The new version of exoskeleton is compared with first version and state of the art devices. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018

Este trabalho consiste no projeto mecânico de um exoesqueleto robótico para paraplégicos com lesões medulares entre T2 a L1, ou seja, sem mobilidade da cintura para baixo e com mobilidade do peito para cima, inclusive das mãos. A utilização do equipamento necessita da utilização de muletas ou andadores. O mecanismo possui seis graus de liberdade, sendo quatro atuados por motorredutores (joelhos e quadris) e dois suportados por molas (tornozelos). Os motorredutores são projetados especialmente para o exoesqueleto, sendo compostos de um motor de corrente continua de imã permanente e um redutor harmônico do tipo panqueca acoplados de forma adequada para minimizar peso e volume. Para calcular os esforços solicitados em cada articulação foi desenvolvido um modelo dinâmico do corpo humano para simular os movimentos que o exoesqueleto é capaz de realizar, que são: marchar, sentar, levantar e subir e descer escadas. O modelo utilizado do corpo humano possui cinco ligamentos rígidos e é capaz de simular movimentos no plano vertical. Os resultados obtidos da simulação são comparados com resultados experimentais da literatura e são considerados satisfatórios. / This work presents a mechanical design of a robotic exoskeleton for paraplegics with spinal cord injuries between T2 to L1, that means, without mobility from the waist down and with mobility from the chest up, including the hands. For using the equipment the paraplegic needs the aid of crutches or walkers. The mechanism has six degrees of freedom, with four degrees actuated by gear motors (knees and hips), and two degrees supported by springs (ankles). The gear motors are designed especially for the exoskeleton. They are composed by an permanent magnet brushless electric motor conveniently coupled with an pancake harmonic speed reducer to minimize weight and volume. For calculating the efforts in each joint a model for the human body is developed to simulate the movements the exoskeleton can perform, which are: walk, sit, standup and climb up and down stairs. The human body model has five rigid links and it is capable to simulate movements in the vertical plane. The results obtained in the simulations are compared very well with experimental results from the literature.

Assistive technologies traditionally rely on either strong actuation or passive structures to provide users with increased strength, support or the ability to perform lost functions. At one end of the spectrum are powered exoskeletons, which significantly increase a user’s strength, but require strong actuators, complex control systems, and heavy power sources. At the other end are orthoses, which are generally unpowered and lightweight devices that rely on their structure’s mechanical behaviour to enhance user’s support and stability. Ideally, assistive technologies should achieve both systems’ characteristics by enhancing human motion abilities while remaining lightweight and efficient. This can be achieved by using distinctive actuators to harness gait energy, towards enhancing human mobility and performance. Pneumatic Artificial Muscles (PAMs), compliant and flexible, yet powerful and lightweight, present a unique set of characteristics compared to other mechanical actuators in human mobility applications. However, given the need of a compressor and power source, PAMs present a significant challenge, limiting their application. In contrast, PAMs can be implemented as unpowered actuators that act as non-linear elastic elements. This thesis aims to develop a wearable lightweight unpowered ankle exoskeleton, which relies on the PAM to harness gait energy and compliment the human ankle biomechanical abilities at the push off movement, thusly assisting the user in propelling the body forward during walking. Presently, limited PAM models have been developed to analyse PAM passive behaviour and to assist in designing and selecting the appropriate PAM for unpowered application. Thus, this thesis aims to develop a passive model for the PAM. To mechanically validate the proposed exoskeleton design, a prototype is fabricated, and tested within an Instron tensile machine setup. The unpowered exoskeleton has shown its ability to provide significant contribution to the ankle timed precisely to release at the push off phase of the gait cycle. Furthermore, the proposed PAM stiffness model is validated experimentally, and accounts for muscle pressure, geometry, material and stretching velocity. This enables the evaluation of the impact of various parameters on the muscle behaviour and designs the PAM accordingly for the unpowered ankle exoskeleton

The main goal of this diploma thesis is to design a hydraulic system for robotic exoskeleton actuation. In the first part of the thesis a list of available sources of exoskeleton designs, is presented, followed by a thorough systematic analysis of hydraulic system elements and their use for this application, is made. The second part of the thesis consists of the hydraulic system design, as well the mechanical design for the hydraulic system which is subsequently tested structurally in the Autodesk Inventor software. The last part of the thesis consists of risk analysis and critical evaluation of thesis‘ results.

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