Yoshiro Hamada

Design and implementation of robust symmetric attitude controller for ETS-VIII spacecraft

To meet increasing mission requirements, communication satellites are being equipped with large flexible antenna reflectors and solar paddles. A typical such satellite, the Engineering Test Satellite VIII (ETS-VIII) spacecraft, was launched into geostationary orbit by the Japan Aerospace Exploration Agency (JAXA) in December 2006. The main mission of ETS-VIII is to support next-generation mobile digital communications, and for this purpose it is equipped with two large deployable antenna reflectors and a pair of large solar paddles that rotate around the pitch axis. The authors are planning to perform on-orbit attitude control experiments using ETS-VIII at the end of its mission life, aiming to develop a baseline for future controller design for this class of satellite using advanced control theories. This paper proposes two degrees-of-freedom control based on robust direct velocity and displacement feedback as a candidate controller technology. The spacecraft modeling and controller synthesis methods are discussed, and a controller implementation for an on-orbit control experiment is presented with simulation results.

Robust Two-Degrees-of-Freedom Attitude Controller Design and Flight Test Result for Engineering Test Satellite-VIII Spacecraft

This paper reports flight test results of robust attitude control for the Engineering Test Satellite VIII (ETS-VIII) spacecraft. The main mission of ETS-VIII is to support next-generation mobile digital communications, and for this purpose it is equipped with two large deployable antenna reflectors and a pair of large solar panels that rotate around the pitch axis. We have proposed and demonstrated several control methods for this spacecraft based on advanced control theories for linear parameter varying multi-input multi-output systems, and in this paper we focus on a two-degrees-of-freedom controller. We describe the controller design methods and present the results of on-orbit flight tests. The controllers superiority is demonstrated by comparing its performance with other controllers.

GAIN SCHEDULING CONTROLLER DESIGN FOR ENGINEERING TEST SATELLITE-VIII

Abstract In this paper a new design method of a gain scheduling controller is described and a design procedure for Engineering Test Satellite (ETS)-VIII is explained. The derived gains are easy to be scheduled since the scheduling law consists of small number of grid points and requires just linear interpolation calculation. Using this method, stability and performance are guaranteed at each parameter value (paddle angle in this case). Some simulation results are provided to show the effectiveness of our controller.

Gain Scheduling Controller Synthesis with Spline-Type Parameter-Dependent Quadratic Forms via Dilated Linear Matrix Inequalities

This paper proposes a new synthesis of a gain scheduling controller based on the approximation of Lyapunov matrices by spline functions. The synthesis condition is described as dilated linear matrix inequalities which can be solved numerically. While in a previous study the derived feedback gains always have the same knots as the approximated Lyapunov matrices, our condition enables the feedback gains to have fewer knots without conservatism. Scheduled gains which are piecewise-linear on a parameter can also be obtained by adding constraints to the proposed synthesis condition.

Design and Implementation of Robust Symmetric Attitude Controller for ETS-VIII Spacecraft

This paper studies the robust attitude control of the large flexible communication satellite ETS-VIII. As a controller candidate, we propose a two-degrees-of-freedom control based on robust direct velocity and displacement feedback, in order to develop a baseline of future controller design technology for this class of spacecraft. For this purpose, the spacecraft modeling and controller synthesis methods are discussed. Then, the controller implementation for on-orbit control experiment is shown with some simulation results.

Flight Test Results for Circular Path Following by Model Predictive Control

Abstract This paper describes a novel lateral guidance law of an unmanned aerial vehicle using model predictive control and shows its flight test results. The guidance law is accompanied with an extended Kalman filter which estimates steady wind velocities in order to follow a pre-specified reference path defined in the ground-fixed coordinate system. A small scale research vehicle, developed by Japan Aerospace Exploration Agency, is used for flight tests and the results show the proposed systems high guidance performance.

Robust attitude control of ETS-VIII spacecraft via symmetric controller

Abstract This paper studies the robust attitude control of large Geo-synchronous communication satellite ETS-VIII. After describing its model features and control issues, a candidate of robust controller design method is proposed. The controller has the form of two-degrees-of freedom control in order to satisfy both specifications of disturbance attenuation and attitude maneuver. The feedback control employs the symmetric controller having the salient robust stability property irrespective of the plant parameters. Its optimization scheme in the H∞ norm sense is discussed. Finally, the on-orbit control experiment plan is shown with some simulation results.

Gain-scheduled preview control for aircraft gust alleviation

This paper deals with a Gust Alleviation control (GA control) system using Gain-scheduled control (GS control) for preview control. Firstly, GS control is applied to discrete-time preview control via LPV (Linear Parameter-Varying) control theory. Secondly, the aircraft model in turbulence is improved. By using the improved aircraft model and the applied GS controller, it is shown that the proposed control system effectively attenuates aircraft acceleration in turbulence and it is robust against aircraft model changes in turbulence through some numerical simulations.

Orbital Experiments of Linearly Interpolated Gain Scheduling Attitude Controller Using ETS-VIII Spacecraft

Abstract This paper describes orbital attitude control experiments carried out on the ETS (Engineering Test Satellite)-VIII in June 2009. These experiments aim to develop a technical basis for the orbital control of a class of future large flexible spacecraft. Several novel robust control laws were tested, including a μ-synthesis based control law, a DVDFB (Direct Velocity and Displacement FeedBack) control law and a linearly interpolated gain scheduling law. Among them, this paper focuses on the gain scheduling law. Experimental results of this control law are presented to show its high control performance and lower computational burden compared with other control laws.

Aircraft gust alleviation preview control with a discrete-time LPV model

This paper deals with a Gust Alleviation (GA) system using Gain-Scheduled (GS) discrete-time preview control. An LPV (Linear Parameter-Varying) model of an aircraft is proposed through a series of approximations of the elements of the state-space matrices based on understanding of flight dynamics. By composing a smaller convex hull and applying GS control, it is shown that the proposed control system effectively attenuates aircraft acceleration in turbulence and it is robust against cruising speed changes through some numerical simulations.