Browsing by Subject "Forward dynamics"
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Item Analysis and synthesis of bipedal humanoid movement : a physical simulation approach(2013-08) Cooper, Joseph L., 1980-; Ballard, Dana H. (Dana Harry), 1946-Advances in graphics and robotics have increased the importance of tools for synthesizing humanoid movements to control animated characters and physical robots. There is also an increasing need for analyzing human movements for clinical diagnosis and rehabilitation. Existing tools can be expensive, inefficient, or difficult to use. Using simulated physics and motion capture to develop an interactive virtual reality environment, we capture natural human movements in response to controlled stimuli. This research then applies insights into the mathematics underlying physics simulation to adapt the physics solver to support many important tasks involved in analyzing and synthesizing humanoid movement. These tasks include fitting an articulated physical model to motion capture data, modifying the model pose to achieve a desired configuration (inverse kinematics), inferring internal torques consistent with changing pose data (inverse dynamics), and transferring a movement from one model to another model (retargeting). The result is a powerful and intuitive process for analyzing and synthesizing movement in a single unified framework.Item Muscle function and coordination of amputee and non-amputee stair ascent(2015-08) Harper, Nicole Guckert; Neptune, Richard R.; Barr, Ronald E; Deshpande, Ashish D; Sulzer, James S; Wilken, Jason MStair ascent is a common activity of daily living and is necessary for maintaining independence in a variety of community environments. However, it can be a biomechanically challenging task. For example, for transtibial amputees the loss of the ankle plantarflexors coupled with the task demands of stair ascent require amputees to develop compensatory mechanisms that utilize the prosthesis and remaining musculature. The overall goal of this research was to use advanced musculoskeletal modeling and simulation techniques in a series of studies to understand how individual muscles contribute to stair ascent in non-amputees and how unilateral transtibial amputees compensate with the prosthesis and remaining musculature during stair ascent. In the first study, a simulation of non-amputee stair ascent was developed to elucidate the contributions of individual muscles and the biomechanical mechanisms by which they accomplish stair ascent. The hip abductors, hip extensors, knee extensors and plantarflexors were found to work synergistically to generate, absorb and/or transfer mechanical power to accomplish stair ascent. In the second study, a simulation of transtibial amputee stair ascent was generated to identify functional deficits and compensations necessary for amputees to ascend stairs. The passive prosthesis was able to emulate the role of the uniarticular plantarflexors, but was unable to replicate the role of the biarticular plantarflexors. As a result, compensations from other muscles were necessary. In the final study, simulations of non-amputee and amputee stair ascent were used to determine the contributions of individual muscles and the prosthesis to dynamic balance control, which was quantified using whole-body angular momentum. The prosthesis was able to replicate the role of the plantarflexors in the regulation of sagittal-plane and, to a lesser extent, transverse-plane angular momentum. However, while the non-amputee plantarflexors contributed minimally to frontal-plane angular momentum, the prosthesis acted to rotate the body towards the contralateral leg, which required additional muscle compensations. By understanding the role of the individual muscles and prosthesis in achieving stair ascent and identifying the compensations used by amputees, this research provides a foundation for designing refined prostheses and targeted rehabilitation programs that improve an individual’s ability to ascend stairs.