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Ko C.-Y.,Korea Orthopedics and Rehabilitation Engineering Center | Ko J.W.,Sejong University | Kim H.J.,Automotive Research & Development Division | Lim D.,Sejong University
International Journal of Precision Engineering and Manufacturing | Year: 2016

Gait and mobility in patients with gait impairment are important in maintaining and improving their physical and psychological health and to return to society. Thus, the aims of the current study were to develop and evaluate a new wearable exoskeleton for gait rehabilitation assistance integrated with a mobility system (RehabWheel) for patients with gait impairment. A wearable exoskeleton was controlled by artificial pneumatic muscles to mimic joint movement; appropriate gait training was then undertaken. In total, 13 healthy males participated in evaluating RehabWheel by comparing joint angle kinematics and muscle activation patterns during walking over ground with RehabWheel and normal gaits. The joint angle kinematics of the hip and knee joints with RehabWheel were similar to those of normal gait despite differences in their magnitude. Additionally, muscle activations in the hip and knee joints were less during RehabWheel gait than normal gait and were associated with joint kinematics. These findings indicate that RehabWheel may have potential for incorporation into gait rehabilitative training assistance combined with a wheelchair platform for movement. This study is valuable for the initial identification of the practical feasibility of this new mobility system with both mobility and gait rehabilitation functions. © 2016, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg. Source

Lee B.,Sejong University | Ko C.,Korea Orthopedics and Rehabilitation Engineering Center | Ko J.,Sejong University | Kim J.S.,Konyang University | Lim D.,Sejong University
Biomedical Engineering Letters | Year: 2015

Purpose: A problem related to musculoskeletal function degeneration may be occurred in patients who experience gait disorders if they use wheelchair-based mobility assistive system only with no gait exercise for long periods of time. Therefore, in current study, we aimed to suggest a new concept of a mobility system that integrates a wheelchair platform, used for the implementation of mobility, and a wearable exoskeleton structure, used for the implementation of gait assistance, and to validate its structural stability and gait control confidence. Methods: A new system was designed and manufactured and its structural stability and gait control confidence were validated. The basic structure of the system was designed based on the platform of a wheelchair for the implementation of mobility, and incorporated a wearable exoskeleton structure formed with six one-degree-of-freedom (DoF) rotational joints for implementing the function of gait assistance. In the case of the wearable exoskeleton part, 12 pneumatic artificial muscles were attached for the 1-DoF flexion-extension operation of the hip, knee, and ankle joints. Results: The results showed that the structural stability of the system was sufficient and the control operation of the system accurately simulated the joint angle change patterns that occur during general normal gait, within an error range of 2.6 ± 10.8%. Conclusions: Our new system suggested may potentially be applicable for gait assistive function incorporated with a wheelchair platform for movement. This study may be valuable because it initially suggest a new concept of the wheelchairtype mobility assistive system with gait assistive function. © 2015, Korean Society of Medical and Biological Engineering and Springer. Source

Jung S.,Korea Orthopedics and Rehabilitation Engineering Center | Bae J.,Dong - Eui University | Moon I.,Dong - Eui University
International Conference on Control, Automation and Systems | Year: 2011

This paper proposes a lightweight prosthetic hand with five fingers that are driven by contraction force of shape memory alloy (SMA). Each finger is composed of SMA-wire mechanism similar to the muscle-tendon structure of human. Finger flexion is performed by contraction force of SMA, but its extension is carried out by a restoring force of a spring mounted on the backside of finger. The developed hand has five fingers, but its total DOF is six due to an under-actuated mechanism. Each finger posture is achieved by control of the SMA length using the electric resistance characteristics of SMA. Therefore the developed hand is possible to perform dexterous hand motions such as tip grasp, precision grasp and lateral hip. Based on a statics analysis of finger mechanism, we estimate the hand grip force. In experiments, we measured the grip force and then compared it to the simulation results. As a result, the maximum grip force was 4.52N by the constant input force, 13N, when the MCP joint angle was 90 degrees. © 2011 ICROS. Source

Bae T.S.,Korea Orthopedics and Rehabilitation Engineering Center
Journal of biomechanical engineering | Year: 2010

When car crash experiments are performed using cadavers or dummies, the active muscles' reaction on crash situations cannot be observed. The aim of this study is to estimate muscles' response of the major muscle groups using three-dimensional musculoskeletal model by dynamic simulations of low-speed sled-impact. The three-dimensional musculoskeletal models of eight subjects were developed, including 241 degrees of freedom and 86 muscles. The muscle parameters considering limb lengths and the force-generating properties of the muscles were redefined by optimization to fit for each subject. Kinematic data and external forces measured by motion tracking system and dynamometer were then input as boundary conditions. Through a least-squares optimization algorithm, active muscles' responses were calculated during inverse dynamic analysis tracking the motion of each subject. Electromyography for major muscles at elbow, knee, and ankle joints was measured to validate each model. For low-speed sled-impact crash, experiment and simulation with optimized and unoptimized muscle parameters were performed at 9.4 m/h and 10 m/h and muscle activities were compared among them. The muscle activities with optimized parameters were closer to experimental measurements than the results without optimization. In addition, the extensor muscle activities at knee, ankle, and elbow joint were found considerably at impact time, unlike previous studies using cadaver or dummies. This study demonstrated the need to optimize the muscle parameters to predict impact situation correctly in computational studies using musculoskeletal models. And to improve accuracy of analysis for car crash injury using humanlike dummies, muscle reflex function, major extensor muscles' response at elbow, knee, and ankle joints, should be considered. Source

Jung S.,Korea Orthopedics and Rehabilitation Engineering Center | Moon I.,Dong - Eui University
Journal of Institute of Control, Robotics and Systems | Year: 2012

This paper proposes a biomimetic finger module to be used in a lightweight hand prosthesis. The finger module consists of finger skeleton and an actuator module driven by SMA (Shape Memory Alloy). The prototype finger module can perform flexion and extension motions; finger flexion is driven by a contraction force of SMA, but it is extended by an elastic force of an extension spring inserted into the finger skeleton. The finger motions are controlled by feedback of electric resistance of SMA because the finger module has no sensors to measure length and angle. Total weight of a prototype finger module is 30g. In experiments the finger motions and finger grip force are tested and compared with simulation results when a constant contraction force of SMA is given. The experimental results show that the proposed SMA-driven finger module is feasible to the lightweight hand prosthesis. © ICROS 2012. Source

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