Adaptive Neural Network-Based Satellite Attitude Control by Using the Dynamic Inversion Technique and a VSCMG Pyramidal Cluster

Mihai Lungu,Romulus Lungu

doi:10.1155/2019/1645042

Abstract

The paper presents an adaptive system for the control of small satellites’ attitude by using a pyramidal cluster of four variable-speed control moment gyros as actuators. Starting from the dynamic model of the pyramidal cluster, an adaptive control law is designed by means of the dynamic inversion method and a feed-forward neural network-based nonlinear subsystem; the control law has a proportional-integrator component (for the control of the reduced-order linear subsystem) and an adaptive component (for the compensation of the approximation error associated with the function describing the dynamics of the nonlinear system). The software implementation and validation of the new control architecture are achieved by using the Matlab/Simulink environment.

Highlights

Small satellites are becoming popular due to their low cost of development and shorter realization time; as a result, there has been a lot of effort to push satellite technology to smaller sizes/mass which would enable the small satellites to accomplish different missions as larger satellites; the modern control architectures’ design for small satellites is a continuing challenge
Depending on the gimbal axes, a Control Moment Gyroscopes (CMGs) can be distinguished to a Single Gimbal CMG (SGCMG), Variable-Speed CMG (VSCMG), and Double Gimbal CMG (DGCMG)
The satellite’s attitude control system (Figure 4) using a cluster consisting of four VSCMGs (Figure 1(b)) is software implemented and validated in Matlab/Simulink environment, for the case of a small satellite

Summary

Introduction

Small satellites (mass < 500 kg) are becoming popular due to their low cost of development and shorter realization time; as a result, there has been a lot of effort to push satellite technology to smaller sizes/mass which would enable the small satellites to accomplish different missions as larger satellites; the modern control architectures’ design for small satellites is a continuing challenge. A CMG acts as a torque amplifier, being suitable for three-axis slew maneuvering by providing the necessary torques via gambling a spinning flywheel [1]. Their main components are the flywheel (the spinning rotor) and the gimbal (the pivot about which the flywheel assembly is rotated); the produced torque’s magnitude is directly proportional to the inertia of the flywheel, the angular speed of the flywheel, and the rate of gimbal’s rotation. SGCMG is a CMG with a constant speed momentum wheel, gimbaled in one axis only; from the torque point of view, the most powerful CMGs are the VSCMGs since these can generate significant control couples (up to 3000 Nm); this kind of actuators can generate much greater torque with less energy when compared to ordinary reaction wheels, normally used on small satellites

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Results

Conclusion