An extremum seeking control based approach for alignment problem of mobile optical communication systems

Optical wireless communication (OWC) has proliferated a wide range of applications in many fields due to its advantages of low-cost, high bandwidth, etc. However, the strict alignment requirements of widely used line-of-sight (LOS) deployments are challenging to be achieved, especially for those moving optical communication systems. In this paper, we propose an extremum seeking control based control strategy to solve the alignment problem for mobile optical communication systems. Our proposed approach consists of two steps: coarse alignment and fine alignment, both rely on the measurements from the vision sensor Pixy2. The coarse alignment uses a feedback proportional-derivative (PD) control and is responsible for tracking and following the receiver. The objective of the fine alignment is to get rid of the effects of any static or dynamic disturbances. The perturbation-based extremum seeking control (ESC) is adopted for a continuous search for the optimal position, where the received optical power is maximum in the presence of disturbance. The proposed approach is simple, effective, and easy to implement.