Lower extremity (LE) work-related musculoskeletal disorders (WMSDs) are known to occur with cumulative exposure to occupational and personal risks. The objective of this disserta-tion study was to find if creating a quantifiable risk detection model for the LE was feasible. The primary product of the literature review conducted for this study resulted in focu-sing the attention of the model development process onto creating the initial model of the LE for assessing knee disorder risk factors.LE occupational disorders affect numerous industries and thousands of people each year by affecting any one of the musculoskeletal systems deemed susceptible by the occupa-tional and personal risk factors involved. Industries known to be affected tend to have labor intensive job descriptions. Some of the numerous industry examples include mining, manufacturing, firefighting, and carpet laying. Types of WMSDs noticed by the literature include bursitis, osteoarthritis, stress fractu-res, tissue inflammation, and nerve entrapment. In addition to the occupationally related disorders that may develop, occupationally related discomforts were also taken into consideration by this study. Gene-rally, both the disorders and the discomforts can be traced to either a personal or occupational risk factor or both. Personal risk factors noted by the literature include a person’s physical fitness and health history (such as past injuries). Meanwhile, occupational risks can be generalized to physical postu-res, activities, and even joint angles. Prevalence data over a three year interval (2003-2005) has found that LE WMSDs make up on average approximately 7.5% of all the WMSD cases reported to the US Occupational Safety and Health Administration (OSHA). When the literature is refined to iii the information pertaining to occupational knee disorders, the mean prevalence percentage of the same three year range is about 5%. Mean cost for knee injuries were found to be $18,495 (for the year between 2003 and 2004).

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In developed countries, an aging society has become a serious issue; many activities of daily living (ADL) are impaired in the elder-ly. In order to improve this situation, it is necessary to develop an assisting method for the human standingup motion because it is considered to be an important factor to ADL. It is unclear, however, how humans coordinate their multiple distributed actuators, muscles, due to the ill-posed problem of redundant their body system. In this paper, we analyze the human standing-up motion based on muscle coordinations, called synergies. A simulation method was developed to make mappings between muscle activations, joint torque, and the human body trajectory; thus, it can be predicted how modular muscle coordinations contribute to the motion. As a result, two primary synergies were extracted and how they coordinate to achieve the motion was elucidated; one synergy strongly affected joint movements and speed of the motion while bending the back and lifting the body up, and the other synergy controls their posture after they lift up their body. These findings could be useful for development of an assisting robotic system for rehabilitative training based on extracted distributed synergies from complex redundant human motion.

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The Exoskeleton is classified inside of a wider technology known as Wearable Robots, that group describes a robotic field who studies the interaction between the human body and the robotics. In those systems, a mechatronics structure is attached to different members of the human body, and while the wearer commands the mechanical system using physical signals, like the electronic stimulation produced by the orders of the brain, or the movements of the body generated by the muscles; the mechanical system do the hard work, like carrying heavier objects or helping the movement of handicaps members of the body. Since its conception in the sixties (Croshaw, 1969) the bibliography speaks about two models of wearable robots: the prosthetics and the orthotics systems. The first group replaces the lost body members, while the second one assists to the body movements or, in other cases, extends the body capabilities.

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The metabolic cost of hopping is reduced with the assistance of an exoskeleton that places a spring in parallel with the entire leg. Energy stored and returned by the spring replaces work that otherwise would be done by muscle-tendon units (MTU). Similarly, exoskeletons bridging only the ankle joint can replace work from ankle plantarflexors. Therefore, the first aim of this study was to test if a spring-loaded ankle exoskeleton could reduce the rate of metabolic energy consumption during hopping. It was hypothesized that net metabolic power would be reduced when an ankle exoskeleton with a spring assisting plantar-flexion was used due to less work being done by the plantar-flexor muscles.

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Досліджуємо задачу математичного моделювання ходи людини з екзоскелетоном. Екзоскелетон (екзоскелет) – це механічний пристрій, який дозволяє збільшити м’язову силу людини за допомогою зовнішнього каркасу; він представляє собою корсет, що складаєься із стержнів, з’єднаних між собою шарнірами. Одним із важливих застосувань екзоскелетона є реабілітація людей із частково (або повністю) втраченими локомоційними функціями нижніх кінцівок. Отримані результати є подальшим розвитком оптимізаційного підходу та алгоритмів математичного моделювання ходи людини.

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