1 MEASUREMENT OF RESULTANT ACCELERATION UTILIZING

This paper describes measurement of resultant acceleration of motion and gravity in 3D space based on sensing a metallic ball position on elastic layer housed in a spherical shell. Construction of different types of silicon rubber is introduced and their displacements against pressure are calculated by using the Hertz' law. Since the resultant acceleration makes the ball roll toward the direction to find a balanced position in the shell, the center position of the metallic ball is measured. The rubber layer is concentric to the shell and liable to distort so that three proximity sensors of high-frequency oscillation type can detect characteristics of sink versus pressure. We show measurement principle of extracting the acceleration by using the characteristics. Experimental results are shown and compared among various rubbers to have the most appropriate design of the sensor. We got practical data such that angular error less than ± 7.4[deg]; amount error less than 2.86 x 10-2 [m/s2]; force sensitivity 4.9 x 10-2[N]; insensible range less than ± 3.8[deg]; periodic time 95[ms]. 1