A Unique Three-Axis Gimbal Mechanism

摘要

Many gimbal configurations are used to point and stabilize the lines-of-sight (LOS) of cameras, FLIRS, LADARs and other sensors in a growing number of military, commercial and scientific applications. The number of gimbal axes incorporated in a design can greatly increase the size, weight, cost and structural flexibility of a system. Therefore an attempt is usually made to accomplish the required field-of-regard (FOR) coverage and LOS control required using the minimum number of gimbals. Two gimbals orthogonal to the LOS is, perhaps, the most common configuration because this arrangement is the minimum number of gimbals required to point a sensor relative to the vehicle on which it is mounted, stabilize the LOS about two orthogonal axes and maintain a stable image of a target in the sensor field-of-view (FOV). However, two gimbals cannot prevent image rotation about the LOS which can result in undesirable image orientation and additional image-degrading smear at the edges of the FOV. When image orientation is important or when the image smear due to the roll motion cannot be tolerated, engineers are often faced with having to add a third gimbal about the roll axis or incorporating complex "deroll" optical assemblies in the sensors optical train. This paper describes a unique gimbal mechanism developed by Raytheon to achieve a third degree of gimbal freedom about the roll axis while minimizing the size and weight added to the system. An incidental advantage of this gimbal concept is that it allows a generally larger sensor aperture than other approaches since it requires less space.