Grey Wolf Optimizer-Based PID Controller Design for Laser Beam Pointing Applications

Abstract

Optical tracking and pointing system are nowadays employed in vast variety of civil and defence applications. Laser beam steering and pointing have always been a challenging task due to complex dynamics of the stabilization platform, mass imbalance, platform vibrations and other environmental factors. This paper presents a systematic approach to modelling and control of fast steering mirror (FSM), used for precise pointing and tracking applications. Initially, a transfer function model is developed to establish the relationship between line of sight (LOS) angle and applied torque. The objective of the control configuration design is to keep the line of sight of the sensor fixed with respect to inertial frame, irrespective of angular disturbances. Grey wolf optimization (GWO)-based PID controller is designed for rate loop configuration of fast steering mirror. The concept of GWO follows the hunting behaviour of grey wolves as search agents. Alpha, beta, delta and omega group of wolves are used for simulating the social hierarchy. The integral of time multiplied absolute error (ITAE) is used as an objective function for proportional integral derivative (PID) controller parameter evaluation using GWO. Although the design of PID controller satisfies the required pointing accuracy of the electro-optical FSM system, but the design of proposed GWO-based PID controller with ITAE as an objective function completely outperforms the existing controller in terms of dynamic input command response and insensitivity to the disturbances.