Abstract
Overall direction-of-action measurement is described. In the measurement, an opaque ball housed in a transparent spherical-vessel is used as a sensor equipment. Since there is sufficient room in the vessel, the ball can move freely under the influence of acceleration of gravity and motion. Specifically, in a static condition, it makes an equilibrium state by indicating the direction of the gravitational field. Under this condition, the ball becomes an optical target and is illuminated by the light from a point source of light. Projected image of the ball in a photosensitive area becomes nearly equal to an ellipse which distinguishes between interior darkness and exterior brightness. Relationships between the displacement of the target and the image data are geometrically analyzed to extract the directional information from the projected image. Flowchart to determine the exact direction resulted from the analysis.
In the experiment, the lens of ball-shaped is used to throw the projected image into the limited photosensitive area. It has been confirmed that the measurement error is within 12 degrees in all directions and the time required is within 500 milliseconds. This method would be applicable to realize direction sensors to prevent platforms, inverted pendulums, and leg systems from inclining, shaking, and falling down.
