Device, system and method for attitude control

#The presently disclosed subject matter relates to devices, systems and methods for attitude control, in particular to such devices in the form of control moment gyroscopes (CMG) and to attitude control systems incorporating such devices, particularly for use in space vehicles and the like.

#Control moment gyroscopes (CMG) are devices used for attitude control, and often form part of an attitude control system (ACS) in space vehicles. ACS's can be used for maintaining a particular fixed orientation of the vehicle with respect to some desired datum, or for changing the attitude of the vehicle when required.

#For example, CMG's are reportedly used in DigitalGlobe's Worldview-1 and Worldview-2 satellites, and in the International Space Station. For example, Astrium and Rockwell Collins Deutschland provide CMG's for small satellites.

#In order to better understand the subject matter that is disclosed herein and to exemplify how it can be carried out in practice, examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

#FIG. 1 illustrates in cross-sectional side view an example of a control moment gyroscope according to an aspect to the presently disclosed subject matter; FIG. 1(a) illustrates an alternative variation of the example of FIG. 1 without the cover and in a first spatial configuration; FIG. 1(b) illustrates an alternative variation of the example of FIG. 1 without the cover and in a second spatial configuration; FIG. 1(c) illustrates an alternative variation of the example of FIG. 1 with a rotor assembly shroud and in a first spatial configuration; FIG. 1(d) illustrates an alternative variation of the example of FIG. 1 with a rotor assembly shroud and in a second spatial configuration

#FIG. 2 schematically illustrates in cross-sectional side view an example of a vehicle comprising a plurality of control moment gyroscope according to an aspect to the presently disclosed subject matter.

#Referring to FIG. 1, an example of a control moment gyroscope (CMG), generally designated 100, according to an aspect of the presently disclosed subject matter, comprises a rotor assembly 190 rotatably mounted to housing 160. The rotor assembly 190 comprises a rotor element 110 rotatably mounted to a gimbal system 140 about rotor spin axis RA, and gimbal system 140 is in turn rotatably mounted to the housing 160 about gimbal axis GA.

#Rotor motor 115, mounted to the gimbal system 140, is provided for controllably spinning rotor element 110 about rotor spin axis RA. While in this example the rotor element 110 is spun at constant speed during operation of the CMG 100, in alternative variations of this example the rotor element 110 can be spun at a controllably variable speed during operation of the respective CMG. In any case, the rotor element 110 has a rotor diameter D, and a moment of inertia when spun about rotor spin axis RA at a particular desired angular speed for operation thereof.

#In this example, gimbal system 140 is configured for controllably tilting the rotor assembly 190 including rotor element 110 about a single gimbal axis GA, different from the rotor spin axis RA and in particular orthogonal to the rotor spin axis RA, to enable tilting of the rotor about one of azimuth and elevation. For example, the gimbal system 140 comprises a gimbal frame 142, journalled to bearings 146 mounted to the housing 160 or part thereof. The gimbal system 140 is controllably driven via gimbal motor 145. Thus, in this example, the rotor element 110 is rotatably mounted to a gimbal system 140 at the frame 142.