Partial gravity Suspension Simulator
Jeff Brewer, Ph.D. Dissertation, Effects of Running with Backpack Loads During Simulated Gravitational Transitions: Improvements in Postural Control, December, 2003
This project involves the use of a partial gravity suspension simulator to determine interactions between loading and variants of the optic flow field in order to aid astronauts as they transition from a microgravity environment (orbit) to the Earth's gravitational field near the Earth's surface (also called 1G).
This picture is a CAD model showing the main features of the partial gravity simulator. See how we constructed the simulator in the photos below.
In the photo, Jeff Brewer is testing out the partial gravity simulator. Our ability to achievenearly constant tension levels throughout a wide vertical travel range is very unique. No other simulator uses our innovative design. Click here for a video clip of Partial G Jumping.
Simulated lunar loping is quite interesting. Actually, it's a lot of fun too! Our subjects did a great deal of this locomotion so that we could better understand the adaptation of postural control mechanisms.
Installation of the virtual environment projection system was the final major component for making the simulator operational.
In order to make full use of the 6 by 8 foot opening in front of the partial gravity simulator, a special projector stand was created to allow for horizontal mounting of the projector. The projector can be configured in the rotated position shown or in a table mount position. Using the projector in this non-traditional orientation requires us to design our software with the rotation incorporated. The virtual environment created with such a large projection system provides an exciting immersive experience for the subject and a rich test bed for locomotion research.
This side view of the partial gravity simulator reveals the 6 camera Motion Analysis system that is being used to collect kinematic data for our subjects. Kinematic data is the data that documents the limb positions and patterns of a subject over time.
The partial gravity simulator is being used to help discover the ways in which the goals of the person (to maintain balance, move efficiently, etc.) and environmental constraints combine to enable successful standing or locomotion both at 1 G (gravitational acceleration close to the Earth's surface) and in altered gravitational environments. Modeling efforts are underway to generate improved simulations of human movement under a variety of environmental conditions. The equation above, borrowed from Newtonian mechanics, highlights the stiffness, viscosity, and acceleration aspects of human locomotion models. Our approach to modeling human motion involves several steps:
- First, we investigated the many ways in which a person can adapt to external (simulated) gravitational changes using controlled experiments.
- Second, we infer how these adaptation strategies can be initiated and controlled by the postural control system. This stage of the process involves an understanding of current neural control modeling efforts.
- Third, models are developed to simulate human performance in response to various environmental challenges.
- Fourth, models are tested and validated during controlled experiments.
Goals of this Research
- Develop better methods for preparing astronauts to adapt their postural control system (for stable standing, walking, and running) as they transition from a microgravity environment to a partial gravity environment or back to the Earth's 1-g environment
- Help maintain and improve the fitness level of astronauts while in a microgravity environment
- Gain further insight into human postural control mechanisms in the hope that improved training/rehabilitation protocols can be developed for disabled individuals
This research is a natural extension of the many human movement investigations and simulation efforts that have been conducted at Texas Tech's Ergonomics Laboratory. This project represents the first time that a partial gravity suspension simulator is being coupled with sophisticated computer generated imagery to create such a compelling and environmentally challenging virtual environment. If you have an interest in learning more about these innovative research techniques for studying postural control, you may contact Dr. Simon Hsiang, through the Texas Tech IE department.
We are able to create a wide array of virtual environments for our subjects to 'walk through'. Give it a try!