NASA'S JOHNSON SPACE CENTER USES VICON SYSTEMS TO TEST SPACE SUITS AND VEHICLES

You may have heard about Vicon motion capture systems being used for the blockbuster hit Gravity, making Sandra Bullock and George Clooney look like they were floating through space dodging satellite debris. But what you may not know is that the same technology is used by NASA to prepare for real-life space missions. NASA's Johnson Space Center (JSC) in Houston, Texas has been using Vicon systems for more than eight years to test the designs of space suits and vehicles.

Although manned missions have been put on hold due to budget cuts, NASA is currently preparing for manned space exploration missions to Mars and the Moon in the coming years. Space vehicles, spacesuits and other hardware are very complex and costly to design and build, requiring numerous iterations to meet performance requirements and costing tens of millions of dollars. NASA's JSC needed a solution to help them design suits and vehicles that, when built, allow astronauts to function effectively.

HUMAN-CENTERED DESIGN

"The main issue was that we used to think of humans last," said Matthew Cowley, senior design engineer at Johnson Space Center. "For example, we'd design and build a vehicle first, and then try to fit a person in it. But when we'd test them with real-life people in spacesuits we'd find that that they couldn't function or move around in the vehicles properly." This could cause problems not only for the mission itself, but for the astronauts involved. So NASA's aim was to find a technology that would enable human-centered design.

NASA chose Vicon systems based on their quality and reliability. They currently use Vicon's Nexus software along with several different types of Vicon cameras, including the Vicon MX System.

JSC engineers use the Vicon systems to ensure that new space suit designs allow astronauts to interact with vehicles and their environment unhindered. Examples include testing how astronauts and their space suits will perform if their vehicle breaks down and they have to walk several miles back to base with a limited oxygen supply. Or verifying whether the design of spacesuits and vehicles enables astronauts to reach and operate controls and safety equipment, such as fire extinguishers, while wearing their suits.

DESIGN IN MOTION

With Vicon systems JSC spacesuit engineers are able to acquire a lot more information to better analyze the motions of different designs, helping them understand not only the gross mobility of the suit, but how each individual component contributes to overall mobility.

To test mobility, engineers used to have subjects move in certain directions, photograph them and then take measurements, which was more time consuming, less effective and less accurate. Now they can have the subjects move in the suit and perform functional tasks to understand which joints they use and how much that joint contributes to the motion.

"The use of motion capture when testing suits is incredibly accurate," said Amy Ross, Johnson Space Center spacesuit engineer. "Testing used to take hours and data analysis would sometimes take months, but now tests only last an hour or so and we can have data available much sooner."

With Vicon systems now in use, JSC can put humans first, allowing them to test how different designs will impact human performance in real-life environments in ways they never could before.


SPACESUIT TESTING IN A MULTI-PURPOSE CREW VEHICLE MOCKUP

For a recent study, NASA needed to evaluate four prototype suits to compare their performance and select the preferred suit components and designs. They needed an advanced, high fidelity motion capture system to evaluate the suits in action in a transparent space vehicle mockup. NASA engineers used a Vicon system to collect suit mobility data, test seat-suit-vehicle interface clearances, and examine suit performance within a multi-purpose crew vehicle (MPCV) mockup. They tested range of motion for various tasks using subjects of different sizes - both suited and unsuited, and in pressurized and unpressurized conditions.

The data revealed that most of the spacesuits tested had sufficient ranges of motion for selected tasks to be executed successfully. Any failures for subjects to complete a task were generally due to problems with suit-vehicle integration, poor agility and perception with pressurized gloves, or field-of-view issues when the subject was seated - rather than insufficient mobility of the new spacesuits.

PARTIAL GRAVITY TESTING

NASA also uses Vicon systems to evaluate suited human performance in reduced gravity. To do this effectively, partial-gravity analog environments ideally need to allow unrestrained freedom of movement while accurately simulating partial-gravity kinetics. In previous studies, two partial-gravity simulations were used to characterize suited human performance. The JSC Space Vehicle Mockup Facility's (SVMF's) partial gravity simulator (POGO) was one of them. A Vicon MX System was used to capture kinematic data in various environments. Retroreflective markers were placed on key parts of the body and hardware. Data was processed with custom-made inverse kinematic and dynamic models using Vicon Bodybuilder, which provided additional flexibility and accuracy over previous models used by the team.

"Vicon was particularly helpful with this partial gravity simulator test," said Cowley. "We were able to see differences with the Vicon system we wouldn't have been able to quantify readily with other methods of motion capture."

TESTING THE CYCLOPS SATELLITE LAUNCHER

Vicon systems are also being used to test the new SSIKLOPS (Cyclops) small satellite launcher, which will throw small satellites into orbit from the International Space Station.

"We put the launcher and a satellite on a frictionless floor and used our Vicon MX system to test the accuracy, speed and trajectory of the launcher," said Cowley. The Vicon system allows JSC to calculate the exact angle the launcher needs to throw the satellites.