INCLINOMETER MEASUREMENT SYSTEM AND METHOD PROVIDING CORRECTION FOR MOVEMENT INDUCED ACCELERATION ERRORS

摘要

The present invention includes a system and a method by which the inclination of a machine element, such as a platform, may be sensed, and errors that might otherwise result from tangential and radial acceleration eliminated. The platform defines orthogonal X and Y axes, and a Z axis orthogonal to both the X and Y axes. The platform is rotatable about an axis extending parallel to the Z axis. The system includes an inclinometer, mounted on the platform at a location spaced from the axis of rotation by a distance r, for providing inclinometer outputs indicating acceleration in the X and Y directions, designated as Ix and ly, respectively. A line from the axis of rotation to the inclinometer forms an included angle B with the X axis. A rate gyro is mounted on the platform. The rate gyro senses the rotational speed w of the platform about the axis of rotation and provides a rate gyro output indicating the rotational speed w. A circuit differentiates the rate gyro output to determine the angular acceleration of the platform dw/dt. A circuit multiplies the angular acceleration by the value r to determine the tangential acceleration of the platform at the point where the inclinometer is mounted r(dw/dt). A circuit resolves the tangential acceleration of the platform at the point where the inclinometer is mounted to determine the X axis component thereof, and resolves the tangential acceleration of the platform at the point where the inclinometer is mounted to determine the Y axis component thereof. A circuit subtracts the X axis component of the tangential acceleration of the platform at the point where the inclinometer is mounted from the acceleration Ix, sensed in a direction parallel to the X axis, and subtracts the Y axis component of the tangential acceleration of the platform at the point where the inclinometer is mounted from the acceleration ly, sensed in a direction parallel to the Y axis. As a consequence, the inclinometer outputs Ix and ly are corrected for errors that would otherwise result from tangential acceleration.