Fundamental Study of Measuring an Overall Direction of Action by Using a Suspended Weight

Abstract

This paper deals with a sensor for the measurement of an overall direction of a resultant force of both gravity and motion acting on objects in-a-3-D space. The sensor uses a spherical weight suspended by springs freely, without producing lateral distortion of the springs. When a platform on which the sensor is attached accelerates, the weight moves toward the direction in which a composite direction of motional and gravitational accelerations is obtained. Displacement of the weight is proportional to the magnitude of the acceleration. Four small-sized magnets are installed on the surface of the weight so that the displacement is measured by using halleffect devices. In order to evaluate total stiffness and natural frequency of the suspended weight, behavior of the weight is analysed. Experimental results show that the measurement error in a steady condition is within 5.8° in all directions of gravity.