Advanced Lyapunov Control of a Novel Laser Beam Tracking System

Abstract

Laser communication systems developed for mobile platforms, such as satellites, aircraft, and terrain vehicles, require fast wide range beam-steering devices to establish and maintain a communication link. Conventionally, the low-bandwidth, high-steering-range part of the beam-positioning task is performed by gimbals that inherently constitutes the system bottleneck in terms of reliability, accuracy and dynamic performance. Omni-Wrist™, a novel robotic sensor mounts capable of carrying a payload of 5 lb and providing a full 180-deg hemisphere of azimuth/ declination motion is known to be free of most of the deficiencies of gimbals. Provided with appropriate controls, it has the potential to become a new generation of gimbals systems. The approach we demonstrate describes an adaptive controller enabling Omni-Wrist™ to be utilized as a part of a laser beam positioning system. It is based on a Lyapunov function that ensures global asymptotic stability of the entire system while achieving high tracking accuracy. The proposed scheme is highly robust, does not require knowledge of complex system dynamics, and facilitates independent control of each channel by full decoupling of the Omni-Wrist™ dynamics. We summarize the basic algorithm and demonstrate the results obtained in the simulation environment