Browsing by Author "Lewandowski, Beth"
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Item Estimation of Lower-body Kinetics from Loading Profile and Kinematics Alone, Without Measured Ground Reaction Forces(48th International Conference on Environmental Systems, 2018-07-08) Thompson, William; Huffman, R. Kenneth; Gallo, Christopher; Dewitt, John; Humphreys, B. T.; Godfrey, Aaron; Frenkel, David; Lewandowski, BethBiomechanical models of human motion can estimate kinetic outcomes, such as joint moments, joint forces, and muscle forces. Typically, one performs an inverse dynamics (ID) analysis to compute joint moments from the kinematics and measured external forces. Sometimes it is impractical to measure ground reaction forces and moments (GRF&M). We devised an empirical method for performing ID analysis of resistance exercises without measured GRF&M. The method solves the multibody dynamics equations of motion with four key assumptions about the GRF&M that reduce the number of unknowns. The assumptions are 1) negligible ground reaction moments, 2) fixed lateral/medial location of the center of pressure (COP), 3) equal fore/aft location of the COP between the feet, and 4) constant angle of the GRF vector relative to vertical in the frontal plane. We used evaluation trials from a prototype exercise countermeasure device to test this approach. Four participants performed squat and deadlift exercises at various loads. We compared results from traditional ID analysis to results without measured GRF&M using our method. We found that joint moment trajectories in the sagittal plane were similarly shaped between the two methods, and the amount of root mean squared error (RMSE), measured by difference in joint moment impulse, was typically under 15% (except for deadlift at the knee, <50%). Non-sagittal joint moment trajectories, which are much lower in overall magnitude, were not always similarly shaped between the two methods. Non-sagittal moments displayed much higher RMSE, with values ranging from 50-1000%. These findings were further supported by validation metrics (Sprague and Geers’ P and M metrics, Pearson’s r correlation coefficient). Based on these findings, we concluded that useful kinetic results are obtained from ID analysis of squat and deadlift exercises, even without measuring GRF&M, as long as the outcomes of interest lie in the sagittal plane.Item Strategy for Risk Quantification of Spaceflight Crew Health and Performance Using Dynamic Probabilistic Risk Assessment(2024 International Conference on Environmnetal Systems, 2024-07-21) Munster, Drayton; Matar, Mona; Gokoglu, Suleyman; Lewandowski, Beth; McIntyre, Lauren; Myers, JerryAt NASA, the Crew Health and Performance (CHP) system represents the span of countermeasures, capabilities, interventions, and tested processes and procedures that in combination work to mitigate the human component of spaceflight mission risk. Across the varying NASA mental models of the CHP system, the different functionalities needed to meet human flight systems standards can be broken down into specific categories (i.e. medical capability, environmental health, behavioral health). These categories can be further broken down into specific subgroups generally associated with the CHP functionalities meant to mitigate or buy down individual human system risks. Taking a similar development approach used by the NASA Human Research Program for modeling risk in the spaceflight medical system, we seek to leverage dynamic probabilistic risk assessment as a means to quantify and relatively assess the human risk state within the crew health and performance domain.12 By utilizing existing tools as integrators, we propose a rapid development strategy for incorporating research and operational data that represent the influence of the CHP system functionalities, in order to provide order of magnitudes estimates of the influence on most human system risks outcomes. By taking a modest cumulative risk approach and limiting scope to primary paths of influence between the CHP functionalities and human system risks, we can quickly prototype the integrative effects of CHP functional combinations to solicit valuable feedback from stakeholders and customers on the data, relationship, and structure of the integration. In this presentation, we will introduce the initial concept and development timeline for this tool and demonstrate a proof-of-concept through an application to the exercise device as a countermeasure in an Artemis-like design reference mission.