High-Speed Attitude Control System for Small Satellite with Micro-CMGs

Abstract

The problem of high-speed maneuver with CMGs (Control Moment Gyros) is considered. In general, CMGs are mostly mounted on large spacecraft, such as ISS (International Space Station) or MIR space station because it is large in size and requires a substantial amount of power. The objective of this paper is to introduce the Micro-CMG, which has been jointly-developed by LSS and TAMAGAWA SEIKI Co., Ltd. This CMG is used to achieve the mission that the small satellite named TSUBAME observes the emission of gamma-ray burst. Furthermore, a time-optimal control problem is solved numerically using the gradient method to obtain the time-optimal input to the pyramid array of four CMGs. The solution gives some indication of the feasibility of the mission of TSUBAME.

Design and Structural Analysis of a Control Moment Gyroscope (CMG) Actuator for CubeSats

“…Each SGCMG has a mass of about 35 g, and the total mass of the system is well below the 500g requirement and is estimated to 250g using avionics from existing ADCS systems currently in orbit. Compared to other CMG developments for CubeSats [6,[12][13][14][15][16][17][18][19], the developed CMG can be a scalable solution for CubeSats of 1 to even 16U in size and the choice of a miniaturized stepper motor in a lean mechanical design brings a very lightweight design which can outperform reaction wheel systems in terms of mass, cost and performance. For example, similar reaction wheels with the same torque capability as the proposed CMG will weigh as much as the mechanical mass of the CMG cluster [4].…”

“…In Table 1, the SwampSat, Tsubame, Lappas, Baker and Cranfield CMGs parameters refer to 4-CMG clusters. The Honeybee CMG is available in multiple configurations and is presented as a single unit and BILSAT-1 used a 2-CMG parallel arrangement [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The first CMG development for small satellites involved a 52.25 mN•m CMG in a classical CMG cluster which was successfully demonstrated using a ground-based air bearing system to simulate satellite attitude motion.…”

“…The proposed CMG design involved the use of a stepper motor for the gimbal as in Ref [6] due to the low power and mass advantages, and was shown to be a viable option for microsatellites with a CMG cluster mass less than 1 kg, as shown in Table 1. Tsubame's CMGs, developed for a 49-kg microsatellite, used hysteresis synchronous motors for the flywheel and hybrid-type stepper motors for the gimbal [18]. Using AC motors generally reduces power consumption compared to DC motors but result in a loss in speed control.…”

Sub-Optimal Control Law for Minimum Energy Attitude Maneuver using CMGs

“…1 and all the pyramid skew angles are the same value. The total angular momentum of pyramid type CMGs is expressed by sum of each CMG angular momentum vector as (8) where…”

“…4,5) In addition, feed-forward control inputs are described by using the optimal control theory considering maneuver time, singularities, or energy consumption. [6][7][8] Although optimal feed-forward control achieves singularity avoidance and optimal maneuvers, initial assumption and iterative calculations are needed to obtain optimal inputs. There are few studies about optimal control laws which have small calculation cost.…”