Space Activity Suit - Bio-Suit

Bio-Suit

The Bio-Suit is an experimental space activity suit under construction at the Massachusetts Institute of Technology at the direction of professor Dava Newman, with support from the NASA Institute for Advanced Concepts. Similar to the SAS in concept, the BioSuit applies a number of advances in engineering and measurement to produce a dramatically simplified version of the SAS design.

Newman has worked extensively in biomechanics, especially in the field of computerized measurement of human movement. Applying this knowledge, Newman's team looked for points on the body where stretching motions did not take place by painting a series of circles over a portion of the body and then watching their deformations as the wearer walked around or performed various tasks. The circles deform into ellipses as the skin stretches over the moving musculature, and these deformations were recorded. After a huge number of such measurements the data is then examined to find all of the possible deformations of the circles, and more importantly, the non-moving points on them where the original circle and the deformed ellipse intersect (at four points per circle). By mapping these points over the entire body, a series of lines are produced that Newman refers to as "lines of non-extension". These lines generally follow the musculation; for instance, there is a prominent line of non-extension running from the shoulder area, down the front of the body, then curving under the armpit. This follows the line where the subscapularis connects to the skeleton.

The primary structure of the BioSuit is built by placing elastic cords along lines of non-extension. As the cords will not be stretched along these lines - at least in normal movements - whatever pressure they provide will be constant even as the wearer moves. In this way, they can very accurately control the mechanical counter-pressure the suit applies. The rest of the suit is then built up from spandex lying between the primary pressure cords. The Bio-Suit team has thus far constructed a number of lower leg prototypes using different materials, including nylon-spandex, elastic, and urethane-painted foam. In one experimental design, kevlar fabric was used between the cords for areas where the expansion was limited. Each suit has to be custom tailored for the wearer, but the complexity of this task is greatly reduced through the use of whole-body laser scans.

The result is a one-layer version of the SAS; it is lighter than the original and considerably more flexible, allowing much more natural motion and decreasing the energy cost of motion. Current versions of portions of the BioSuit have consistently reached 25 kilopascals (190 mmHg; 3.6 psi), and the team is currently aiming for 30 kilopascals (230 mmHg; 4.4 psi) for a baseline design. As mechanical counter-pressure has proven difficult for small joints such as those in the hands, the BioSuit baseline design uses gas-filled gloves and boots, in addition to a gas-filled helmet.