서강대학교

초록/요약

Recently, spinal cord injury (SCI) patients are increasing due to various accidents such as traffic accidents, fall-down injury, etc. Less than 1% of SCI patients experience complete neurological recovery by hospital discharge, and thus the most of the SCI patients are diagnosed as tetraplegia and paraplegia. Since the development of medical and rehabilitation technology increases the life expectancy of these SCI patients, the demands of robots that can support medical care, rehabilitation, and daily living of these patients are increasing steadily. Several powered exoskeletons developed have been developed and even commercialized for paraplegics due to the SCI. Since the mechanical design concept of the commercial powered exoskeletons is focused on the weight reduction of the entire robotic system, the actuation power is limited, and thus the semi-active actuation methods (e.g., controllable dampers, brakes, or clutches) are often utilized. This is a good strategy for assisting walking, as walking motion is efficient if the natural dynamics of the human body can be fully utilized. However, this was not a possible strategy for daily living; the insufficient actuation power cannot make the pilot walk on a tilted path, a ramp, stairs, and uneven terrain. Therefore, targeting the daily living, the powered exoskeletons were designed to have large actuation power and full controllability. Also, for the motion control of a powered exoskeleton, the normal walking is often applied as a reference input. When the natural dynamics of the human body can be utilized and the displacement of the center of gravity (CoG) is possible, the normal walking is effective to increase the gait speed with the minimal energy consumption. Paraplegics due to the SCI, however, are able to voluntarily move neither the legs nor their waist, and thus they cannot control the CoG at all. In addition, the degree of freedom (DoF) of the powered exoskeletons is less than that of the human body; therefore, it is difficult to expect that the paraplegics naturally control the CoG even with the help of the powered exoskeletons. Consequently, the normal walking is not necessarily the best option for such complete paraplegics. In this dissertation, a mechanical design concept, a control strategy, and a gait trajectory generation method of a powered exoskeleton for paraplegics are introduced. The requirements of a successful powered exoskeleton for paraplegics may include: robust gait stability, balancing, weight shifting, locomotion speed, safety and practicality (i.e., size, volume, weight, and energy efficiency). In this aspect, the mechanical design concept and control strategy of the powered exoskeleton for paraplegics are proposed. Also, a new gait pattern, called forward leaning walking (FLW), is proposed for the motion control of a powered exoskeleton for paraplegics. The proposed method enables to transfer the CoG to the leading leg by the height difference between the leading leg and the trailing leg. The CoG can be located at the leading leg by the proposed method despite the change of the ground slope. The proposed method is verified by clinical experiments.