| 摘要 |
An actuator (1) for mechanically supporting a structure such as an optical or radio telescope reflector (3). The actuator (1) is free to precess about a pivot point (C) which is fixed with respect to the supporting cell structure (9). This can be accomplished by gimballing the actuator (1) using vertical (13) and horizontal (17) trunnions. This gimballing arrangement permits radial and axial excursions of each actuator ball (29) to compensate for gravity vector variations as the reflector (3) is moved to point towards its target, and to compensate for thermal expansion variations between the reflector (3) and cell (9). Fine axial position adjustments are accomplished by a rotating nut (43) or a rotating screw (63) configuration in conjunction with a stepper motor (47 or 67). Motor (47 or 67) can receive its commands from a real-time closed loop system sensitive to axial position or axial load. A counterweight (57) appended to each actuator (1) balances the radial gravity loads among each of many actuators (1) and hard points (5) used to support the reflector (3). This system produces almost total decoupling of axial loads from radial loads, enabling the reflector (3) to "float" radially, permitting a thinner lighter reflector (3) which adjusts to the deflections of a lighter support cell (9) rather than being supported rigidly in a very stiff heavy cell (9).
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