RBF network based adaptive sliding mode control for solar sails

Abstract

Purpose The purpose of this paper is to resolve complex nonlinear dynamical problems of the pitching axis of solar sail in body coordinate system compared with inertial coordinate system. And saturation condition of controlled torque of vane in the orbit with big eccentricity ration, uncertainty and external disturbance under complex space background are considered. Design/methodology/approach The pitch dynamics of the sailcraft in the prescribed elliptic earth orbits is established considering the torques by the control vanes, gravity gradient and offset between the center-of-mass (cm) and center-of-pressure (cp). The maximal torques afforded by the control vanes are numerically determined for the sailcraft at any position with any pitch angle, which will be used as the restriction of the attitude control torques. The finite/infinite time adaptive sliding mode saturation controller and Bang–Bang–Radial Basis Function (RBF) controller are designed for the sailcraft with restricted attitude control torques. The model uncertainty and the input error (the error between real input and ideal control law input) are solved using the RBF network. Findings The finite true anomaly adaptive sliding mode saturation controller performed better than the other two controllers by comparing the numerical results in the paper. The control torque saturation, the model uncertainty and the external disturbance were also effectively solved using the infinite and finite time adaptive sliding mode saturation controllers by analyzing the numerical simulations. The stabilization of the pitch motion was accomplished within half orbit period. Practical implications The complex accurate dynamics can be approximated using the RBF network. The controllers can be applied to stabilization of spacecraft attitude dynamics with uncertainties in complex space environment. Originality/value Advanced control method is used in this paper; saturation of controlled torque of vane is resolved when the orbit with big eccentricity ration is considered and uncertainty and external disturbance under complex space background are settled. Moreover, complex and accurate nonlinear dynamical model of pitching axis of solar sail in body coordinate system compared with inertial coordinate system is provided.

Adaptive Finite-time Attitude Tracking Control for Solar Sail with State-dependent Torque Saturation

“…Baculi and Ayoubi (2017) designed a fuzzy attitude controller for solar sail, where a control parameter was applied to modify the torque saturation, but the actuator allocation and the design of control parameter were not considered. Lian et al (2018) proposed a saturated attitude controller for solar sail based on the adaptive sliding mode control theory where the stability analysis of the control system was given, but only the dynamics of pitch axis was taken into account.…”

“…Actually, neglecting the coupling between attitude angles and control torques would affect the actuator allocation since the three-axis control torques are functions of both the attitude angles and the actuators' variables. Lian et al (2018) choose the torque saturation as the maximum value that the actuator could offer with attitude angle of 90 degree, and assumed that the actuator should be always ready for the maximum torque for any other attitude, but the solutions of actuators' variables may not always exist for the required torque. The potential failure in actuator allocation would also damage the stability of attitude control system due to the considerable error between the controller's output and the affordable torque from the actuator system.…”

Neural Network Supervision Control Strategy for Inverted Pendulum Tracking Control

“…Kumar et al [15] use adaptive control technology to deal with tracking problems. At present, many researchers [16][17][18][19][20] have conducted in-depth studies on various inverted pendulum models using different control methods.…”

Robust fault-tolerant attitude control of spacecraft using hybrid actuators

“…This problem motivates fault-tolerant control design for spacecraft attitude maneuvers (Li et al , 2019; Liu et al , 2019), which usually requires reliability and guaranteed performance (Fan et al , 2017; Zhang et al , 2020; Sun et al , 2020). Furthermore, actuator saturation is another practically key issue (2018; Jia et al , 2019), which may degrade the closed-loop performance or even give rise to instability and has attracted enormous research effort (Shen et al , 2015a, 2015b; Lu et al , 2016; Lian et al , 2018). However, few of the existing papers has taken into account actuator misalignments, actuator faults and control saturation simultaneously.…”