Getting Around by Voice Control

Outside his orbiting capsule in his own space suit, an astronaut will be a man beset by problems. A brief pulse of power from a backpack rocket will start him moving in any direction he desires, but it will take another carefully calculated pulse to stop him, still others to move him up, down, backward or into a turn. How will he handle the continuous need to control his versatile little rocket without letting that one job keep him too busy for other useful work?

Answers to such questions fill a 287-page data-packed report to the National Aeronautics and Space Administration prepared by Honeywell Inc. Once they started working on the problems of personal space flight control, Honeywell engineers were soon tangled in startling complexities. The most obvious scheme was one of the first to be discarded. Levers similar to the conventional aircraft control stick would be all but impossible of operation by a man with his arms in the stiff sleeves of an inflated space suit. And more important, an astronaut's hands would have to be free for a variety of exacting tasks.

A search began for subtler ways to control an AMU (Astronaut Maneuvering Unit). Some of them, such as motions of the leg, feet, head or torso, were quickly rejected by Honeywell engineers as too difficult for an astronaut floating in a clumsy space suit. Somewhat more attractive was control by the astronaut's eye movements. A photocell watching the position of the eyeball could steer the astronaut to any target at which he looked steadily. But such control would not be enough. The astronaut would sometimes want to move backwards, and in any case he must always have his eyes free for looking from side to side. Control by small electrical currents generated when an astronaut moved certain chosen muscles was rejected as too difficult to make practical.

By Mouth. Finally Honeywell settled on the astronaut's mouth. Lip and tongue motions might do the job, but there is not much room in a space helmet, and extra equipment placed there would probably interfere with necessary speech over the radio. And the Honeywell men had a strong hunch that most astronauts would object to apparatus hitched to their lips or tongue.

A better possibility was the astronaut's breath. He might puff gently into sensing devices that would convey his commands to the AMU. But this system would not be accurate, and the extra puffing would waste oxygen and deposit undesirable moisture in the space suit's helmet.

Then tone was considered. The astronaut might hum different notes, and a simple device could translate this code into control commands. This system, which has been widely used in telephone switching, was rejected, says the report, because it relies "on musical skills not naturally possessed to any marked extent by the average astronaut."

By Words. The final decision was in favor of control by words. There are plenty of devices available that can distinguish with precision between a limited number of spoken words. The Honeywell men figured that a vocabulary of ten normal words was enough to give all needed commands. When the astronaut wants his gas jets to turn him to one side, say the engineers, all he should have to do is say "yaw" into his microphone. If he wants to make a fast turn, he will say "yaw, yaw, yaw." Direction of the yaw will be determined by saying "plus" or "minus," and the computer that is listening will tell the mechanism to execute the command.

Other word commands are "X," "Y" and "Z," which call for motion in one of three directions. The astronaut can also say "stop," to end whatever action is going on, or "cage" to shut down the whole apparatus. "Stop-plus" and "stop-minus" might be used to switch on the gyro apparatus that keeps his attitude stabilized within two different degrees of accuracy.

No voice command apparatus has yet been built, but the Honeywell engineers say that all its components can be available in the near future. And they are satisfied that the astronauts will approve. There will be no uncomfortable gadgets hitched to their tongues or eyes; all they will need do is speak clearly in a simple, natural code. The computer will pay no attention to the rest of their speech--at least as long as they are careful not to use the code words in meaningful combinations.

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