Article
Minimum-Time Attitude Maneuver and Robust
Attitude Control of Small Satellite Mounted with
Data Relay Communication Antenna
Kota Mori
1,
* and Masaki Takahashi
2
1
School of Science for Open and Environmental Systems, Graduate School of Science and Technology,
Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
2
Department of System Design Engineering, Faculty of Science and Technology, Keio University,
3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan; takahashi@sd.keio.ac.jp
* Correspondence: birdkouta@keio.jp; Tel.: +81-80-6639-3168
Received: 14 January 2019; Accepted: 4 March 2019; Published: 11 March 2019
Abstract:
This paper proposes a nonlinear control method for carrying out Minimum-time satellite
attitude maneuver and antenna motion which have robustness against model uncertainty. In recent
years, small Earth observation satellites have been utilized and expected to maneuver rapidly
in missions such as multi-target acquisition. On the other hand, small satellites need to send the
observation data to ground station. Recently, small Earth observation satellites acquire high-resolution
data, resulting in an increase in the time required for data communication. Thus, small satellites need
to use inter-orbit communication link through Data Relay test satellite sending data from Data Relay
communication (DRC) antenna. In conventional operations, the antenna motion is implemented after
satellite attitude maneuver. However, this method has a time delay between the completion of the
attitude maneuver and the start of data communication. The purpose of this study is to extend the
time of earth observation and data communication by carrying out satellite maneuver and antenna
motion concurrently. Because small satellite mounted with DRC antenna has large mass ratio of the
antenna, we cannot ignore time variability of the moment of inertia of the whole system and reaction
torque generated by antenna motion. Hence, in order to take the influence of the antenna motion into
consideration, we combine a satellite attitude control system and an antenna drive system into one
control system by governing equations and constructing the optimal control problem. We convert the
optimal control problem into a NLP by discretizing the control input (a series of pulses) to minimize
the final time of the total maneuver that includes the antenna adjustment. In addition, it is considered
that a model uncertainty and unknown disturbance occurs in real space. Thus, we have to design
feedback controller to secure robustness in model error and unknown disturbance. Accordingly
in order to propose a nonlinear control method for carrying out minimum-time satellite attitude
maneuver and antenna motion which have robustness against model uncertainty and unknown
disturbance, we calculate a reference attitude by application of optimal control input torque to ideal
satellite model and design servo controller by using state-dependent Riccati equation (SDRE) control
method in order to track time-variant reference attitude.
Keywords:
small satellite; Data Relay Communication antenna; attitude control; Minimum-time;
Nonlinear Programming problem; State-dependent Riccati equation; Robust control; nonlinear
servomechanism
1. Introduction
Japan promote the development of high resolution small-sized satellite like ASNARO (advanced
satellite with New system architecture for observation). The ASNARO project is an Earth observation
Appl. Sci. 2019, 9, 1001; doi:10.3390/app9051001 www.mdpi.com/journal/applsci
