| 摘要 |
This invention is a rotary actuator in which the angular momentum of a ratationally pointed structure is offset by the angular momentum of a compensating inertia. The compensating inertia structure is rotational driven relative to the pointed structure across a differential gear which assures the ratio of the rotational rate of the compensating inertia to the rotational rate of the pointed structure is a negative constant. The differential gear consist of a stationary gear fixed to the base vehicle, a platform gear axially coincident with the stationary gear but free to rotate relative to the stationary gear being fixed to the pointed structure. Planetary gears mesh with the stationary and planetary gears and are driven relative to the compensating inertia structure by planetary drive motors. The planetary drive motors are part of the rotating compensating insertia structure and are symmetrically positioned around the stationary gear axis driving the planetary gears around the periphery of the stationary gear and around the periphery of the platform gear. Because the diameter of the stationary gear is larger than the diameter of the platform gear assures the ratio of the rotational rate of the compensating inertia structure of the rotational rate of the pointed structure relative to the stationary gear axis is a negative constant. The magnitude of the rotational rate difference between the compensating inertia and pointed structure can be designed as large as desired by making the platform gear diameter approach the stationary gear diameter. Mechanical backlash is eliminated at rotational rate polarity changes by assigning one planetary drive motor polarity to one motor and the opposite polarity to a different planetary drive motor. Motor redundancy is achieved by having at least one planetary drive motor available in the event of a motor failure. Since the redundant planetary drive motors are part of the compensating inertia, they reduce the mass of inactive inertia structure required to achieve the desired compensating inertia magnitude.
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