Background:Approximately 15% of the world’s population are affected bysome kind of disability where over 150 conditions may affect the human gaitpattern. The ability to ambulate with ease is important for overall well-being.Various assistive devices have been developed to improve mobility of theirusers. A lot of research is currently focused on ankle exoskeletons, showingpromising results in providing important assistance during stance phase of gait. Objective:To investigate how different combinations of active and passiveelements in an ankle exoskeleton affects the metabolic cost of walking. Methods:Musculoskeletal simulations were carried out in OpenSim Moco.Different assistive configurations were tested over one gait cycle using a pas-sive element, an active element, and a parallel connection of the both. Parame-ter values were modified to find the most optimal setup for reducing metaboliccost. Results:All assistive configurations were found successful in reducing bothwhole-body metabolic cost and the metabolic cost of the plantarflexors whencompared to the unassisted gait. Most whole-body metabolic cost reductionwas found when using a passive spring with resting length of 0.28 m and stiff-ness of 6 kN/m in parallel with an active motor capable of providing forceequal to 150% of body weight. The most reduction in metabolic cost of theplantarflexors was also found for a parallel connection of elements, but herewith a 100% body weight motor and spring with rest length of 0.19 m andstiffness of 10 kN/m. With higher assistance, more reduction in ankle mo-ment generated by the muscles was observed. Conclusion:Powered ankle exoskeletons are promising in terms of minimiz-ing metabolic cost during walking due to assistance during late stance phaseof gait for ambulators requiring plantarflexor assistance. Keywords:Simulation, exoskeleton, ankle, moco.

This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), and includes a novel concept for supporting the weight of a person's arm or robotic linkage. The design is capable of supporting weights held near the hand, and provides support regardless of position. This support is provided with a pantograph. The upper-arm and forearm bars are mirrored by smaller copies. Force applied to a pull point on the scaled copy of the arm is flipped and applied at a support point on the forearm or to a tool near the hand. Two exoskeletons, using different linkages make use of the pantograph design. These include the Panto-Arm Exo, which uses it's slim, reduced size to comfortably assist users in lifting their arm, and the Panto-Tool Exo which is designed for a support point that coincides with a mass representing a heavy tool. The differing topologies and purposes of these two devices resulted in different qualities regarding their ability to lift weight. The Panto-Arm Exo was specifically used in human subject testing, in which fourteen users wore electromyography electrodes and performed simple arm movements and holding tasks. While the Panto-Arm Exo did not undergo stringent design improvements or user-specific optimization, the device was shown to reduce muscle use in the measured upper-arm muscles for certain arm positions. / Master of Science / This thesis is centered upon the published A Novel Method and Exoskeletons for Whole-arm Gravity Compensation (Turner, Hull 2020), includes a new way to lift a person's arm or robotic linkage. The design can lift weights close to the hand regardless of arm placement. This support is provided with a pantograph. The pantograph design is based on a mirrored, smaller copy of the upper-arm and forearm bars, which is pulled downwards to create an upwards support force at chosen support point. This point is based underneath the forearm or at a heavy tool. The concept is similar to pushing down on a teeter-totter in order to prevent the other end from dropping. Two exoskeletons, using different linkages make use of this pantograph design. The Panto-Arm Exo is slim and light. It is made to help users in lift their arm by supporting its weight. The Panto-Tool Exo has a support point that located where a mass representing a heavy tool sits. The changes between both devices means that they display different lifting qualities. The Panto-Arm Exo was worn by 14 people, also wearing electrodes that measured muscle activation. These users held weights and moved their arms around while muscle activation was recorded. While the Panto-Arm Exo wasn't fine-tuned or adjusted for individual people, it was shown to reduce muscle activation in the measured upper-arm muscles for some of the arm placements.

An underactuated exoskeleton design for walking assistance is presented and evaluated. The exoskeleton uses one motor per leg and makes use of a pantograph to reduce the overall profile and allow the exoskeleton to closely follow the shape of the user's leg. Support is provided between the ball of the user's foot and their waist by compressing a spring in parallel with the user's leg during Stance Phase. The exoskeleton has a mass of 14.0 kg (30.8 lbs) and was tested up to a supplied spring force of 323.6 N (72.75 lbf) which equates to around 161.8 N (36.38 lbf) of assistive force at the waist. Range of motion tests showed minimal restriction at the knee and ankle, but some restriction of the hip. Human subject experiments using a simple gait detection method based on GRF at walking speeds from 0.45 m/s to 1.12 m/s (1.0 mph to 2.5 mph) were performed and showed an increase in the time between actual heel strike and predicted heel strike of approximately 0.05 seconds to 0.1 seconds. Lastly, calculations are presented examining the effect of exoskeleton assistance on the biological joint moments and optimizing the actuator design to reduce power consumption. The actual performance of the exoskeleton is compared with the calculations based on the joint angles during a typical walking cycle. / Master of Science / A design for an exoskeleton capable of providing walking assistance without requiring a motor for every joint is presented and evaluated. The exoskeleton uses one motor per leg and makes use of a pantograph to reduce the required size and allow the exoskeleton to closely follow the shape of the user's leg. Support is provided between the ball of the user's foot and their waist by compressing a spring attached beside the user's leg while the user's foot is on the ground. The exoskeleton weighs 14.0 kg (30.8 lbs) and was tested up to a supplied spring force of 323.6 N (72.75 lbf) which equates to around 161.8 N (36.38 lbf) of assistive force at the waist. Range of motion tests showed minimal restriction at the knee and ankle, but some at the hip. Testing with a human participant using a simple method for determining when to apply support and remove it based on the forces measured at the user's foot were performed at walking speeds of 0.45 m/s to 1.12 m/s (1.0 mph to 2.5 mph). These tests showed an increase in the time between when the heel of the foot initially hits the ground and when the exoskeleton code determined that it occurred of approximately 0.05 seconds to 0.1 seconds. Lastly, calculations are presented examining how exoskeleton assistance affects what is felt at the joints of the user and determining what spring stiffness would best reduce the power required from the motors. The actual performance of the exoskeleton is compared with the calculations based on the joint angles during normal human walking.

The goal of this thesis is to use biomechanical data describing shoulder motion to determine optimal parameters to assist in the design of a 5 DOF active shoulder exoskeleton. This thesis will provide a proof of concept on optimization techniques using motion data using a simplified 3 DOF model to facilitate future work implementing a full 5 DOF model. Optimization will be performed to determine the link lengths and, consequently, the locations of the joints of the exoskeleton by considering the human's workspace to maximize range of motion and promote user safety by minimizing collisions of the exoskeleton with the user and with the exoskeleton itself. The thesis will detail the development of computational models of the human and proposed exoskeleton, the processing of experimental data used to estimate the human's capabilities, optimization, and future work. This work will contribute to a large-scale NSF-funded project of building an upper body exoskeleton emulator. The emulator will promote the widespread adoption of exoskeletons in industry by providing a test-bed to streamline the rapid design of various assistance profiles for various users and tasks. / Master of Science / An exoskeleton is a robotic assistive device used in industrial and rehabilitative settings. This thesis will use data describing how the human shoulder moves during certain tasks to help design an exoskeleton to assist with theses tasks. A model of the human shoulder and a model of the exoskeleton will be developed and used in an optimization to figure out the best dimensions of the exoskeleton links to support the human's movements.

Work-related musculoskeletal disorders (WMSDs) continue to occur despite an increasing understanding of the risk factors that initiate these disorders. Ergonomics is commonly seen as a health and safety approach that has no influence on performance, a perspective potentially hindering intervention proposals in practice. Highlighting potential performance benefits can facilitate intervention cost-justification, along with the traditional focus on reducing exposure to injury risk. The main objective of this research was to examine the dual influences (i.e., on performance and injury risk) of two distinct types of interventions: adding adjustability, as a commonly advocated approach when considering ergonomics early in the (re)design phase to change task demands; and using exoskeletons to enhance worker capacity. A simulated drilling task was used, which was considered informative as it entailed diverse demands (precision, strength, and speed) and permitted quantifying two dimensions of task performance (productivity and quality). The dual influences of three levels of workstation adjustability were examined first; increasing adjustability improved performance, with this benefit occurring only when a given level of adjustability also succeeded in reducing ergonomic risk. Across examined conditions, several significant linear associations were found between risk (e.g., Strain Index score) and performance metrics (e.g., completion time), further supporting an inverse relationship between these two outcomes. The dual influences of three distinct passive exoskeletal designs were investigated/compared subsequently, in a simulated overhead drilling task and considering the potential moderating effects of tool mass and precision requirements. Specific designs were: full-body (Full) and upper-body (Arm) exoskeletons with attached mechanical arms; and an upper-body (Shl) exoskeleton providing primarily shoulder support. Both designs with mechanical arms increased static and median total muscle activity while deteriorating quality. The Shl design reduced shoulder loading while increasing dominant upper arm loading and deteriorating quality in the highest precision requirements. Influences of both increasing precision and tool mass were fairly consistent across the examined designs. As such, no single design was obviously superior in both physical demands and performance. Although future work is needed under more diverse/realistic scenarios, these results may be helpful to (re)design interventions that achieve dual benefits on performance and injury risks. / PHD

As farmers continue to get older, they will likely face age-related disabilities that impede their ability to work and increase risk of suffering serious injuries. One of the major age- related diseases is arthritis, which currently accounts for about 40% of disability cases in agriculture nationwide. The effect of arthritis on farmers is profound because it reduces their physical strength, joint range of motion and is a source of joint pain, all culminating in the lack of ability to perform routine activities regularly and safely. One way to decrease the rate of injuries is by reducing the strength and joint loading required to perform these activities through the use of wearable robotics. As opposed to existing solutions that focus only on injury prevention, this thesis will present an active, knee-assist exoskeleton intent on providing 30% of the necessary joint rotation force to perform activities such as sit-to- stand actions and the ascent/descent of stairs and hills. The device will be a lightweight, unobtrusive cable-driven exoskeleton actuated by distally-worn electric motors. We hope that use of the exoskeleton will result in increased ranges of motion and overall reduction of stress on the wearer's body, which will minimize the effects of arthritis and ultimately improve safety and quality of life. / Master of Science / As farmers continue to get older, they will likely face age-related disabilities that impede their ability to work and increase risk of suffering serious injuries. One of the major age-related diseases is arthritis, which currently accounts for about 40% of disability cases in agriculture nationwide. The effect of arthritis on farmers is profound because it reduces their physical strength, joint range of motion and is a source of joint pain, all culminating in the lack of ability to perform routine activities regularly and safely. One way to decrease the rate of injuries is by reducing the strength and joint loading required to perform these activities through the use of wearable robotics. As opposed to existing solutions that focus only on injury prevention, this thesis will present an active, knee-assist exoskeleton intent on providing 30% of the necessary joint rotation force to perform activities such as sit-to-stand actions and the ascent/descent of stairs and hills. The device will be a lightweight, unobtrusive cable-driven exoskeleton actuated by distally-worn electric motors. We hope that use of the exoskeleton will result in increased ranges of motion and overall reduction of stress on the wearer’s body, which will minimize the effects of arthritis and ultimately improve safety and quality of life.

Grasp stability was studied and researched upon by various research groups, but mainly focused on robotic grippers by devising conditions for a stable grasp. Maintaining grasp stability is important so as to reduce the chances of the object slipping and dropping. But there was little focus on the grasp stability of robotic exoskeleton gloves and most of the research was focused on mechanical design. A robotic exoskeleton glove was developed as well as novel methods to improve the grasp stability. The exoskeleton glove developed is intended for patients who have suffered paralysis of the hand due to stroke or other factors. The robotic glove aids them in grasping objects as part of daily life activities. The glove is constructed with rigidly coupled 4-bar linkages attached to the finger tips. Each linkage mechanism has 1- Degree of Freedom (DOF) and is actuated by a linear Series Elastic Actuator (SEA). Two methods were developed to satisfy two of the conditions required for a stable grasp. These include deformation prevention of soft objects, and maintaining force and moment equilibrium of the objects being grasped. Simulations were performed to validate the performance of the algorithms. A battery of experiments was performed on the integrated prototype in order to validate the performance of the algorithms developed. / Master of Science / An exoskeleton glove is robotic device that can aid people who suffer from paralysis of their hands caused by a stroke or other factors with the primary goal of allowing them to regain the basic ability of grasping objects and thereby improving their quality of life. The exoskeleton glove developed in this research is focused on objects grasping assistance rather than for rehabilitation purposes. Since the exoskeleton glove lacks conscious senses like a human hand typically possesses, it may not be able to apply sufficient grasping force or may apply excessive force than required irrespective of the object being grasped. In order to ensure that the exoskeleton glove applies the proper amount of force, two novel methods were developed which help improve the overall grasping performance of the robotic glove. These methods use sensors that enable the glove to react to the force interaction changes that exists between the hand and the object being grasped through the exoskeleton glove. The first method detects any deformation that may occur while grasping a soft object and applies lesser force accordingly to prevent further damage to the object. The second method uses motion sensor to detect any movement by the user while grasping the object and applies corrective forces so that the object doesn’t slip from the hand. A prototype was designed and integrated and the two methods were tested on the prototype to validate them.

Individuals with upper limb motor deficits due to neurological conditions, such as stroke and traumatic brain injury, may exhibit hypertonia and spasticity, which makes it difficult for these individuals to open their hand. The Hand Orthosis with Powered Extension (HOPE) Hand was created in 2018. The performance of the HOPE Hand was evaluated by conducting a Box and Blocks test with an impaired subject. Improvements were identified and the HOPE Hand was mechanically redesigned to increase the functionality in performing grasps. The original motor configuration was reorganized to include active thumb flexion and extension, as well as thumb abduction/adduction. An Electromyography (EMG) study was conducted on 19 individuals (10 healthy, 9 impaired) to evaluate the viability of EMG device control for the specified user group. EMG control, voice control, and manual control were implemented with the HOPE Hand 2.0 and the exoskeleton system was tested for usability during a second Box and Blocks test.

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.