| Summary: | 碩士 === 國立臺灣大學 === 醫學工程學研究所 === 97 === Conventional reciprocal gait orthosis (RGOs) configuration contains hinge hip joints, which restrict the anatomical hip joint to perform abduction/adduction and internal/external rotation. The restriction leads to an unwanted compensatory movement in order to achieve a pelvic rotation that is required in normal gait. The compensation generates a zig-zag progression through a whole lower limb rotation and sacrifices a normal gait straight progression. The abnormal progression and lower limb rotation are thought to be the cause of high energy cost for the paraplegic patients when wearing RGOs.
The excessive energy consumption of RGOs has been comprehensively discussed in the past literature. Yet, there were few discussions about the effects of RGOs’ hip mechanism on gait dynamics and efficiency in paraplegic and diplegic patients.
The purpose of this study was to apply robotics to orthotic joint designs. The results were used to improve the hip joint of RGOs and hip orthoses. The designed joint determined the movement of the pelvic and the thigh to guide the movement of the anatomical hip joint. The inverse and forward kinematics were used to design orthotic joints and simulate the movements of anatomical hip joint in RGOs and hip orthosis applications, respectively.
Denavit-Hartenberg convention was used to present the relationship of orientations and position from pelvis to thigh. And the robotic mechanisms were assumed to be fixed on the body side near human’s anatomical hip joint or be fixed on body anterior during a normal walking, and the mechanism allowed two rotations (flexion/extension and abduction/adduction) and one translation. An “abduction cam” was designed by the results of inverse kinematics. The RGO’s hip joint mechanism was replaced by the abduction cam mechanism and used to simulate and predict the orthotics gait.
The kinematics of hip joint movement with the abduction cam is much closer to normal than with the inclined-axis hinge joint system that is commercially available. The guidance of thigh and pelvic rotation movements in swing is particularly better.
In conclusion, this study laid out theoretical work for the design of a new hip orthosis, and the effect of the mechanism on the lower limb movement was simulated and discussed. The abduction cam could guide well in flexion phase and generate appropriate abduction for patients, but the abduction is not satisfied in extension phase. In extension phase, as a view from the foot, the abduction cam supplies abduction moments for hip, as abductor firing at the initial of the single stance. The energy consumption will be saved by the external hip abduction moment, and will be very helpful for paraplegia patients.
Future studies are needed to develop a prototype of the abduction cam, and to prove the effectiveness by carrying out clinical experiments.
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