Development of kinematics for gimballed mirror systems

In order to meet the performance contraints imposed on modern stabilization and tracking systems, a wide variety of gimbal and optical configurations are required. As mechanisms become more complex, understanding the kinematic relationships within the assemblies becomes less intuitive. Therefore careful analysis is needed to insure the mechanisms operate properly and to identify appropriate means for control. The analysis should include the development of kinematics for transforming vectors through the gimbal set. Such vectors could be vehicle angular rate, target position, and gravity. This paper outlines the general steps to be followed in such a development and then presents a specific gimballed mirror system to serve as an example for other development of this type. This system uses a strapdown detector and mounts the optics (two front-surface flat mirrors and a derotation prism) on gimbals to stabilize and point the Line-of-Sight. Finally, this system is also used to illustrate the analysis of the kinematics necessary for maintaining the target image upright in the displayed field-of-view.