2003 — 2004 |
Chang, Young-Hui |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Reflexes During Cat Locomotion Across Speed and Gait
[unreadable] DESCRIPTION (provided by applicant): The overall objective of the proposed research is to quantify the neuromechanical influence of sensory feedback from the ankle joint over a range of speeds and gaits during cat locomotion. By studying how reflexes function across a range of speeds and gaits, we propose to partition out the relative contributions of peripheral modulation of reflexes at each activity level. Furthermore, we will elucidate a predictive relationship between reflex modulation and locomotion speed/gait. Self-reinnervation of certain muscle groups crossing the ankle joint will result in the effective loss of localized proprioceptive feedback. We will make biomechanical measurements during locomotion before and after self-reinnervation to determine their functional importance during locomotion. Biomechanical data will be quantified using high-speed video, 3-dimensional joint kinematics and linear algebraic analysis. The findings will provide valuable information about how reflexes are used during locomotion and how this importance changes across different speeds and gaits. This information can then be extrapolated to make predictions about how reflexes may be modulated to assist in rehabilitation techniques for human patients suffering from neurological diseases affecting motor control of movement and gait.
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0.907 |
2007 — 2008 |
Chang, Young-Hui |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Interjoint Coordination and Compensation in Rat Locomotion Using X-Ray Kinematics @ Georgia Institute of Technology
[unreadable] DESCRIPTION (provided by applicant): The rat has come to the forefront of many nerve injury models and will likely be associated with the next greatest biomedical breakthroughs in the areas of spinal cord injury and peripheral nerve injury. Groundbreaking methods for studying specific disease models in rodents are increasingly prevalent in the biomedical research community. However, the ability to quantitatively and mechanistically resolve locomotor functional outcomes to test more subtle and sophisticated hypotheses is currently unavailable and must also be further developed. Measuring whole limb movement patterns (kinematics) with skin markers to quantify locomotor function is often the gold standard in other areas of movement science. However, this can present a problem when studying small mammals like rats due to the large errors attributed to movement of the skin relative to the underlying skeleton. The objectives of this project are to develop and test a high-speed x-ray kinematics system for quantifying locomotor deficits in rat hindlimb coordination after specific peripheral nerve injuries. Achieving this objective will provide two immediate, deliverable end-products that will impact areas of biomedical research concerned with quantifying locomotor behavior in rats: (Aim 1) development of an x-ray kinematics locomotor assay that will provide a gold standard for rat locomotor patterns and provide context for the more common skin marker kinematics methods; and, (Aim 2) a theoretical foundation for understanding basic principles of locomotor compensation after specific neuromuscular injuries such as a muscle denervation. The long-term goals of this project are to provide a means to accurately study the different contributions of short-term compensation, long-term compensation and sensory feedback to the control of locomotion after nerve injury. In advancing the study of locomotor function in rats, the results of this project could easily be applied to mouse locomotion and have great implications for the study of locomotion in the hundreds of genetic knockout mouse models. This work will generate technology capable of accurately quantifying motor deficits that map to subtle neuromuscular lesions and form a theoretical basis for studying the mechanisms that drive recovery in more complex lesions such as sciatic nerve injury or spinal cord injury, with eventual applicability to genetically modified rats and mice. Rats and mice are overwhelmingly the research model of choice to study and develop therapies for spinal cord injury and other serious, debilitating insults to the nervous system. Currently the ability to relate specific neuromuscular injuries to specific biomechanical gait deficits in rats does not exist, so the scientific community can only make general conclusions about the efficacy of potential treatments. This project: (1) will generate technology capable of accurately quantifying biomechanical gait deficits that relate to very specific neuromuscular injuries, and (2) generate a theoretical basis for understanding the neuromechanical compensation mechanisms in more complicated injuries such as spinal cord injury and potential for application to genetic causes of gait disorders. [unreadable] [unreadable] [unreadable]
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1 |
2009 — 2015 |
Chang, Young-Hui |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Career: Dynamic Control of Immediate Locomotor Compensations in the Leg @ Georgia Tech Research Corporation
"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
The major objective of this 5-year CAREER Development project is to discover unifying principles that guide locomotor compensation and integrate these scientific principles into prosthetics and orthotics education. The research goal is anchored by a central hypothesis that a common set of joint compensation principles underlie whole leg function during locomotion even when faced with different mechanical constraints. This project will be performed in the Comparative Neuromechanics Laboratory at the Georgia Institute of Technology. Using a well-controlled experimental model of human locomotion the investigators will place mechanical constraints on the locomotor task (e.g., limb movement frequency, amplitude, foot placement precision) and on individual joints during the task (e.g., torque loading, range of motion limitation, mechanical coupling between joints). They will also test whether there is a hierarchical organization to the control parameters of the leg during locomotion. This research will be integrated into prosthetics and orthotics education in three tiers: (1) development of a web-based teaching module, (2) curriculum development in a unique entry-level Master of Science in prosthetics and orthotics, and (3) a website to promote integration of basic research into related programs.
Achieving these project goals will deliver broad impacts to science and science education through better understanding of how nature exploits redundancy in complex systems. The intellectual merit of this work will be to address basic questions about the control and compensatory strategies of legged locomotion that apply across constraint types and across organizational levels. The compensation principles provide a theoretical framework for understanding how normal, healthy human locomotion adapts to different terrains (e.g., asphalt, grass), minor injuries (e.g., ankle sprain) and chronic pathologies (e.g., leg amputation, stroke). Areas of science and engineering can then employ these compensation principles to improve prosthetic and orthotic design, control of biomimetic robots and gait rehabilitation methods. The broader impacts of acting locally through a structured program of outreach and education development are that it will effectively build a bridge for integrating basic science into the first graduate program in prosthetics and orthotics, a historically applied and clinically oriented field.
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0.93 |
2010 — 2011 |
Chang, Young-Hui Liu, Cheng-Yun Karen (co-PI) [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Task Space Control of Normal &Pathological Locomotion @ Georgia Institute of Technology
DESCRIPTION (provided by applicant): The broad, long-term objectives of this proposal are to quantitatively characterize, compare, and simulate the use of task space control in normal and pathological gait due to lower limb amputation. Extensive research has detailed joint kinematics and kinetics of human locomotion and movement control with normal and various motor function disorders. Yet, relatively little is known about how humans relate joint-level information to higher-level locomotor goals. Understanding basic biomechanical tenets governing leg control before and after injury will provide a general theoretical framework for creating new therapeutic interventions for pathological gait disabilities. This project proposes to use behavioral locomotion experiments to study task space control in both healthy intact human subjects and in both Below-Knee (transtibial) and Above-Knee (transfemoral) amputees walking on prosthetic legs. This project will use extensive data analysis to quantify and characterize task space control during locomotion using variables identified from biomechanical models and by eigenanalysis. Based on the analytical results, a further study will create a physics-based computer simulation of pathological amputee gait with corrective joint torques computed from the differences discovered between normal and amputee gait. The general hypothesis of the project is that humans control locomotion by precisely guiding their legs through a predefined task space while allowing flexibility in joint-level dynamics and that more proximal limb amputations will result in greater losses in this ability to exploit task space redundancy. Three specific aims to study the use of task space control during locomotion are addressed: normal human locomotion (Aim1);pathological gait due to lower limb amputation (Aim2);and, the evaluation and simulation of the changes from normal to pathological human walking (Aim3). Achieving these three aims will provide immediate deliverables by quantifying functionally relevant task variables for normal human gait and a theoretical understanding of how these control variables change after a neuromechanical pathology such as lower limb amputation. This work will develop new analytical tools to quantitatively assay normal and amputee gait, however, it will also be generally applicable to the study of all gait pathologies. It could further impact future therapeutic approaches for gait rehabilitation that use task-level rather than joint-level rehabilitation goals and inspire control systems for the rapidly growing field of rehabilitative robotic devices. The proposed work will also form a theoretical framework for future studies of the neural mechanisms underlying leg control during locomotion. PUBLIC HEALTH RELEVANCE: Nearly all diseases that affect our muscles, bones, and nerves have the potential to affect our ability to walk normally, which is critical to our independence and quality of life. This project combines exciting new physics-based computer simulation techniques with biomechanical experiments on humans to learn how motor redundancy in the legs is exploited to generate precise repetitive movements and how this control strategy is compromised by lower limb amputation. This work will generate new analytical tools to understand how normal and pathological gait due to lower limb amputation is controlled and restored, but will have broad implications for the treatment of all gait disorders.
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1 |
2012 — 2014 |
Chang, Young-Hui Liu, Cheng-Yun Karen (co-PI) [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Task Space Control of Normal & Pathological Locomotion @ Georgia Institute of Technology
DESCRIPTION (provided by applicant): The broad, long-term objectives of this proposal are to quantitatively characterize, compare, and simulate the use of task space control in normal and pathological gait due to lower limb amputation. Extensive research has detailed joint kinematics and kinetics of human locomotion and movement control with normal and various motor function disorders. Yet, relatively little is known about how humans relate joint-level information to higher-level locomotor goals. Understanding basic biomechanical tenets governing leg control before and after injury will provide a general theoretical framework for creating new therapeutic interventions for pathological gait disabilities. This project proposes to use behavioral locomotion experiments to study task space control in both healthy intact human subjects and in both Below-Knee (transtibial) and Above-Knee (transfemoral) amputees walking on prosthetic legs. This project will use extensive data analysis to quantify and characterize task space control during locomotion using variables identified from biomechanical models and by eigenanalysis. Based on the analytical results, a further study will create a physics-based computer simulation of pathological amputee gait with corrective joint torques computed from the differences discovered between normal and amputee gait. The general hypothesis of the project is that humans control locomotion by precisely guiding their legs through a predefined task space while allowing flexibility in joint-level dynamics and that more proximal limb amputations will result in greater losses in this ability to exploit task space redundancy. Three specific aims to study the use of task space control during locomotion are addressed: normal human locomotion (Aim1); pathological gait due to lower limb amputation (Aim2); and, the evaluation and simulation of the changes from normal to pathological human walking (Aim3). Achieving these three aims will provide immediate deliverables by quantifying functionally relevant task variables for normal human gait and a theoretical understanding of how these control variables change after a neuromechanical pathology such as lower limb amputation. This work will develop new analytical tools to quantitatively assay normal and amputee gait, however, it will also be generally applicable to the study of all gait pathologies. It could further impact future therapeutic approaches for gait rehabilitation that use task-level rather than joint-level rehabilitation goals and inspire control systems for the rapidly growing field of rehabilitative robotic devices. The proposed work will also form a theoretical framework for future studies of the neural mechanisms underlying leg control during locomotion. PUBLIC HEALTH RELEVANCE: Nearly all diseases that affect our muscles, bones, and nerves have the potential to affect our ability to walk normally, which is critical to our independence and quality of life. This project combines exciting new physics-based computer simulation techniques with biomechanical experiments on humans to learn how motor redundancy in the legs is exploited to generate precise repetitive movements and how this control strategy is compromised by lower limb amputation. This work will generate new analytical tools to understand how normal and pathological gait due to lower limb amputation is controlled and restored, but will have broad implications for the treatment of all gait disorders.
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1 |
2017 — 2021 |
Childers, Walter Chang, Young-Hui |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Nri: Int: Collab: Accelerating Large-Scale Adoption of Robotic Lower-Limb Prostheses Through Personalized Prosthesis Controller Adaptation @ Georgia Tech Research Corporation
Experiencing a lower limb amputation is a life-changing event. A person with lower-limb amputation relies heavily on a leg prosthesis to support himself/herself and stay mobile. However, most leg prostheses in current use are unpowered, which can cause great inconvenience. For example, these unpowered prostheses cannot propel the amputee users forward in walking, and cannot push them up while standing up or climbing stairs. With the advances in medical robotic technologies, powered robotic leg prostheses are starting to become more common. These powered prostheses can help amputees to walk more easily and naturally, and also provide power to support activities previously unattainable or extremely difficult with existing unpowered prostheses (such as standing up and stair climbing). On the other hand, these robotic prostheses are much more complex than the existing unpowered prostheses, so tuning such a prosthesis to fit an individual user is very challenging and time-consuming, requiring numerous office visits with a clinician over a long period of time. This is one of the main reasons why powered leg prostheses have not gained extensive use among the amputee users.
In this project, the research team will help to solve this problem by developing a new method to automate the prosthesis tuning process. The main idea is to use a pendant-like wearable sensor to measure upper body motion, which provides rich information about how well the prosthesis is being controlled to help the user to walk and perform other basic tasks of daily life. The new method will use such information and gradually tune the controller parameters over time without the need for constant clinical supervision. To develop this method, the researchers will study how an experienced prosthetist tunes the prosthesis parameters and develop an algorithm to mimic this process. Furthermore, the upper body motion will be used to infer the amputee user's intention more precisely, so the prosthesis can reliably understand what the user intends to do even if he/she changes the motion pattern while learning to use the robotic prosthesis.
By conducting research in this project, the researchers aim to develop a complete Personalized Prosthesis Controller Adaptation (PPCA) system, which provides personalized controller adaption on two levels: 1) automatic motion controller tuning, and 2) automatic intent recognizer adaptation. The researchers anticipate to make significant contributions to the related scientific areas, including: 1) a novel wearable sensor that incorporates an inertial measurement unit (IMU), capacitive sensing (for sensor-torso relative motion), and advanced signal processing to provide reliable trunk motion information; 2) fundamental understanding of robotic prosthesis-assisted amputee locomotion, and how human expertise-based tuning optimizes its gait quality; 3) a novel quasi-supervised adaptation of classifier-based intent recognizer, which provides the advantages of the traditional supervised learning while avoiding its major weakness (highly effective in adapting to changing human conditions, and no repeated training sessions or human-conducted data labeling required). Impacts of this project will also be generated by its various education activities, including the introduction of robotic technologies to the future prosthetic clinicians through a renowned prosthetics and orthotics education program, and the creation of hands-on robotic projects in undergraduate research, which can also serve as important tools in the K-12 outreach to attract children at different age groups to the science and engineering fields.
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0.93 |