|
Originally appeared in "Aerospace Technology Innovation" Volume 6, Number 5 September/October 1998
Docking one spacecraft with another will be
much easier, thanks to smart computer software being developed at NASA's Ames Research Center. The neural net software
will "learn" the motion behavior of a spacecraft as it flies, so it will not undershoot or overshoot docking targets..
The Ames "neurocontroller" will be able to automatically dock a spacecraft of unknown
mass with another by flying the spacecraft short distances in different directions and learning the handling
characteristics of the craft, according to Dr. Robert W. Mah, an Ames research scientist. "The neurocontroller
automatically enables precise, safe docking. This software learns similar to the way human beings learn—by experience,
handling the spacecraft," Mah said. The neural net software used in the controller is similar to that used to
automatically focus home camcorders.
"Current methods used to dock spacecraft will be improved to make docking easier for astronauts," Mah said. "Docking a
spacecraft by manual joystick control depends on the skill of the operator."
Manual docking can be slower than desired, and in some cases precious fuel can be wasted. Conventional software has been
used to automatically dock spacecraft, when the spacecraft mass properties are known, according to Mah. "But conventional
automated docking doesn't work well when the exact mass is unknown or changing robot arm positions alter spacecraft
flight characteristics," Mah said.
A future "worker bee" spacecraft, which would be used during construction in space, might grab a construction part and
rotate, Mah said. "The arm and the part held by the spacecraft have a tendency to keep rotating," he added. In contrast,
the same spacecraft equipped with the neurocontroller would immediately learn the new "feel" of the way the spacecraft
rotates in space while firing its impulse jets. The smart software would then precisely slow the spacecraft's rotation by
"burning" the jets for just the right amount of time.
The Ames neurocontroller has not yet been tested in space. "We hope to do space tests eventually, but first we need to
fine-tune the software in the lab, making more realistic simulations with test vehicles floating on a cushion of air
over a special granite table," Mah concluded.
The neural net software is a form of artificial intelligence. It can be used in the medical field for neurosurgery and
for breast and prostate cancer surgery to identify tissues and tumors with less damage. The software has the ability to
"learn" the characteristics of a system or different kinds of tissues, such as brain or tumor tissue. In the aircraft
industry, neural net software could be used to safely land damaged planes and could be an effective tool for the next
generation of flight controllers.
|
