Spacecraft payload positioning with respect to a virtual pivot point

#This invention relates generally to spacecraft and, in particular, to methods and apparatus for providing payload positioning with respect to a virtual pivot point.

#The assignee of the present invention manufactures and deploys spacecraft for communications and broadcast services. To meet market demands for advanced services from such spacecraft, spacecraft payloads of increased size and improved pointing performance are required. For example, there is a demand for increased aperture antenna reflectors, having diameters of three meters or greater, and larger, more complex, radio frequency (RF) feed arrays. A payload element, such as, for example, an antenna reflector, and/or an RF feed array, often require one or more positioning mechanisms configured to provide for (i) initial deployment of the payload element from a stowed launch position to an (on-orbit) operating position, and/or (ii) on-orbit steering of the reflector or feed to provide precise pointing.

#Such positioning of spacecraft payload elements has conventionally been performed, by, for example, linear or rotary actuators as illustrated in FIG. 1A and FIG. 1B, respectively. Referring to FIG. 1A, spacecraft main body structure 100 is coupled to reflector 120 by way of panel 110. Panel 110 may have a deployment hinge (not shown) proximate to spacecraft 100 to facilitate an initial deployment from a stowed (launch) configuration to a deployed (on-orbit) configuration. Operation of linear actuators 132 results in rotation of reflector 120 about each of two mutually orthogonal axes 136 and 138 defined by pivots 134. Referring now to FIG. 1B, rotation of reflector 120 in each of two mutually orthogonal axes 136 and 138 may, alternatively, be accomplished by way of two rotary actuators 140.

#Features of the invention are more fully disclosed in the following detailed description of the preferred embodiments, reference being had to the accompanying drawings, in which:

#FIGS. 1A and 1B illustrate known antenna positioning techniques.

#FIG. 2 illustrates a four-bar linkage according to an embodiment.

#Throughout the drawings, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components, or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the drawings, the description is done in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention as defined by the appended claims.

#Specific exemplary embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms, and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

#It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. It will be understood that although the terms “first” and “second” are used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another element. Thus, for example, a first user terminal could be termed a second user terminal, and similarly, a second user terminal may be termed a first user terminal without departing from the teachings of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The symbol “/” is also used as a shorthand notation for “and/or”.