Missile Seeker Gimbal Feedforward Testbed
The Feedforward Testbed program was a demonstration project to develop a mirror-stabilized beam-steering mechanism for use in small missiles. Missile seekers are generally a gyroscope stabilized gimbal mounted to the front of a missile that attempts to track the target.
At the time of this project, miniature stabilization-quality solid-state gyroscopes did not exist, and mechanical “spinning wheel” gyroscopes were the only viable solution for tactical military stabilization applications. A brassboard, three-axis seeker was developed to serve as a controls testbed for hardware and algorithm development. A three-axis, mirror-steered gimbal assembly was chosen to provide full hemispheric coverage. As the seeker had to look straight ahead, the “keyhole”, or “gimbal lock” characteristics of a two-axis gimbal was not feasible. The assembly was too small to support the mechanical gyroscopes available at the time, so a feedforward control system was developed that achieved stabilization by slaving the relative position and rate of the mirror to a strapdown inertial navigation system. The effort led to United States Patent 6609037, “Gimbal pointing vector stabilization control system and method”.
The program included the design and fabrication of an all-new flexible controller to support the significant hardware, software, and algorithm development effort associated with the project. The controller was a rack-mounted design with modular processor, I/O, gyroscope electronics, resolver electronics, and servo-amplifier assemblies. The design allowed for rapid reconfiguration and upgrade of any one component with minimum system-level reconfiguration. The general utility of this controller was quickly recognized, and additional copies of the “rapid prototyping system” were produced and employed for years on subsequent programs. Additional details can be found in the Low-Profile Antenna case study and in the technical paper, “Feedforward Stabilization Testbed”, DeBruin, et al, Proc. SPIE, Vol. 2739, 1996, pp. 204-214.