Electronic Design

Fluid-Sphere Gyro Has High Sensitivity

A radical departure from conventional gyro design has resulted in a device that can detect motion too minute to be measured. The miniature gyro's unique sensing ability makes it especially suitable for stabilizing space platforms carrying extremely delicate equipment.

The new space-system component, according to the manufacturer, Sperry Gyroscope Co., Great Neck, L.I., N.Y., is a fluid-sphere gyroscope, called the SYG-2000. It has a sensitivity believed to be as low as 1/100 of a sec of arc.

The heart of the mechanism is a spinning mass of liquid, confined within a hollow sphere.

In operation, a cylinder is constantly rotated by two hysteresis motors at either end. Inside this cylinder is the hollow sphere filled with silicon fluid. Any angular motion of the rotor from this axis produces variations in pressure between the fluid and the cavity wall. Pressure is sensed by a series of diaphragms buried in the rotor-cavity assembly. Pressure variations force the diaphragms to oscillate at an amplitude proportional to the angular displacement between the rotor and fluid axes. The diaphragms act as a miniature microphone to convert pressure variations into electrical signals.

The two-axis SYG-2000 contains fewer than half the number of parts required by a conventional gyro. Anisoelastic drift is 0.003 deg per hour per g2.

The tolerance requirements for the fluid-containing sphere are so lax that Sperry is able to use an investment casting without further machining.

The unit can be delivered in five to six months at less than $2000. (Electronic Design, Oct. 25, 1961, p. 56)

TAGS: Components
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