Tuning of Pulse-Width Pulse-Frequency Modulator using PSO: An Engineering Approach to Spacecraft Attitude Controller Design

In this paper, a new technique for fine tuning of spacecraft autopilots based on pulse-width pulse-frequency (PWPF) modulators is presented. PWPF is one of the most commonly used approaches to control signal modulation. Its main application is found in spacecraft controllers to produce discontinuous on-off control signals for two situational actuators. The main reasons for the popularity of this method are the reduced energy consumption and the quasi linear operation with high degrees of freedom in adjustment. But, due to multiplicity and nonlinear relationship between parameters, fine tuning of PWPF is known to be an engineering problem. Similar complexity is observable in adjusting the incorporated controller parameters. These involvements regarding the industrial and academic background of PWPF are not properly explored. The paper shows how particle swarm optimization (PSO) can be invoked to set both controller and PWPF parameters. Several spacecraft autopilots have been designed to show effectiveness of the proposed method.