Abstract
The development of an optical sensor for measuring overall direction of action is treated. The measurement principle is based on distortions found in the projected image of a ball moving freely in liquid within a spherical vessel under the in fluence of the acceleration of gravity and motion. The sensor has an opaque ball housed in a bigger, transparent, spherical vessel. The opaque ball is illuminated by light coming from a pinhole, which is located close to a subminature lamp. The light passes through the spherical vessel to a translucent screen placed behind the vessel, and the image silhouetted on the screen is projected through a lens toward an area sensor. This lens is ball shaped so as to reduce the large image from the screen. Digitized signals from the area sensor are transferred into a microcomputer to obtain the farthest and nearest positions of the image from the center of the sensor. Next, the direction of the opaque ball is calculated.
The measurement is carried out in a static condition. Thus, the sensor output stands for the direction of the gravitational field. Experimental results are presented to show that the angular errors are within 12° for the overall direction. This sensor can be applied widely to the measuring of angular variations from the direction of the gravitational field.
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