Modeling of Astronaut
Jumping and Locomotion

Human mechanisms for control of posture and motion are normally optimized to perform in Earth's 1-G environment. When astronauts adapt to the microgravity of spaceflight, they exhibit quantitatively different control strategies, often measured as degradation in performance for balance, locomotion, and jumping tasks. This collaborative research effort between our laboratory and the Neuroscience Laboratory at NASA Johnson Space Center focuses on the development of a full-body, multisegment biodynamic model of human postural and motion control, including simplification and integration of physiological subsystem descriptions.

This model will provide a framework for testing three hypotheses:

1. Astronauts exposed to microgravity during spaceflight will exhibit quantitative differences in whole-body motion post-flight during jumping and locomotion, including modified intersegmental coordination, altered impact and energy transfer schemes, and decreased stability
2. Alterations in astronaut biodynamics postflight result from adaptive adjustments to specific full-body motor control strategies, especially hierarchical control arrangements, vestibular and proprioceptive feedback loops, and musculoskeletal impedance modulation;
3. The modeled adaptive control strategies will elucidate motor behavior adopted in microgravity, clarify readaptation upon return to 1-G, and allow assessment of full-body motor control across a continuum of G-levels.

This study will complement ongoing research into trunk, head, and eye movement coordination strategies, lower-limb kinematics, and single-joint energy transfer at the Johnson Space Center Neuroscience Laboratory. Full body dynamic models will provide greater insight into motion control requiring the coordination of many muscles and joints. Furthermore, multi-segment and polyarticulate models are necessary to examine control of impedance and inertial properties, which have important consequences when considering limb-environment interactions.