Abstract Because control moment gyroscopes (CMGs) can generate a large torque compared to reaction wheels, they are used as actuators for attitude control of large spacecraft. However, when the number of Single-Gimbal CMG (SGCMG) units is five or less, there can be internal singularities that cannot generate torque around the desired direction. To construct a system that has no internal singularities, six or more SGCMGs are required, because an orthogonally arrayed, three scissored-pair CMG system has no internal singularities. Because CMG singularities are disruptive for attitude control, a great deal of effort has been devoted to overcoming the CMG singularity problem; the various designs include Variable-Speed CMGs (VSCMGs), Double-Gimbal CMGs (DGCMGs), and Double-Gimbal Variable-Speed CMGs (DGVSCMGs). However, these designs still have problems, such as slow response to torque generation commands about the wheel axis in VSCMGs and DGVSCMGs, and difficulty in precise attitude tracking when perturbation torque is generated to avoid singularities. To overcome the problems of the traditional CMG configurations, this paper proposes a new CMG system configuration that we call the Double-Gimbal Scissored-pair CMG (DGSPCMG) system. Because the DGSPCMG system is a hybrid system combining a Scissored-Pair CMG and a DGCMG, the DGSPCMG system does not have internal singularities except at the origin and along the x-axis. Moreover, this system can recover from an internal singularity by null motion only, and from outer singularities (saturation singularities) by steering the scissored-pair gimbals only. Thus, the generation of perturbation torque is unnecessary for recovering from singularities, and a precise attitude tracking maneuver can be more easily achieved. This paper presents a conceptual design of a DGSPCMG system and describes a steering control law for the proposed system. Furthermore, the validity of the proposed steering control law is demonstrated through numerical simulations and results of comparison experiments are shown to demonstrate the advantage of the DGSPCMG over a VSCMG.

中文翻译：

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双云台剪叉CMG转向控制律

摘要 由于控制力矩陀螺（CMG）与反作用轮相比能产生较大的扭矩，因此被用作大型航天器姿态控制的执行器。但是，当单万向节 CMG (SGMCG) 单元的数量为五个或更少时，可能会存在无法在所需方向周围产生扭矩的内部奇点。要构建一个没有内部奇点的系统，需要六个或更多 SGCMG，因为正交排列的三剪刀对 CMG 系统没有内部奇点。由于 CMG 奇点对姿态控制具有破坏性，因此已投入大量精力来克服 CMG 奇点问题；各种设计包括变速 CMG (VSCMG)、双万向节 CMG (DGCMG) 和双万向节变速 CMG (DGVSCMG)。然而，这些设计仍然存在问题，例如 VSCMGs 和 DGVSCMGs 中对围绕轮轴的扭矩生成命令的响应缓慢，以及在产生扰动扭矩以避免奇异性时难以精确的姿态跟踪。为了克服传统 CMG 配置的问题，本文提出了一种新的 CMG 系统配置，我们称之为双万向节剪式对 CMG (DGSPCMG) 系统。因为 DGSPCMG 系统是一个结合了 Scissored-Pair CMG 和 DGCMG 的混合系统，所以 DGSPCMG 系统除了在原点和沿 x 轴之外没有内部奇点。此外，该系统可以仅通过零运动从内部奇异点恢复，并且仅通过操纵剪刀对万向节从外部奇异点（饱和奇异点）恢复。因此，从奇异点恢复不需要产生扰动扭矩，并且可以更容易地实现精确的姿态跟踪机动。本文介绍了 DGSPCMG 系统的概念设计，并描述了所提出系统的转向控制律。此外，通过数值模拟和比较实验的结果证明了所提出的转向控制律的有效性，以证明 DGSPCMG 优于 VSCMG。