Device for deploying and pointing an equipment item carried by a spacecraft
A device for deploying and pointing an equipment item is disclosed including a mobile platform for receiving the equipment item, a carrier integrally secured to a wall of a spacecraft, and three identical linear actuators which connect the carrier to the mobile platform and are suitable for moving the platform in translation along one axis and for orienting the platform in rotation about two axes. Each linear actuator including a first portion connected to the platform by a universal joint, a second portion connected to the carrier by a pivot connection, a motor, and a screw/nut joint interconnecting the two portions, each universal joint being suitable for preventing the screw/nut joint from rotating about the axis, such that driving the motor causes a translational movement between the first and the second portion.
1. A device for deploying and pointing an equipment item, comprising:
a mobile platform for receiving the equipment item,
a carrier integrally secured to a wall of a spacecraft, and
three identical linear actuators connecting the carrier to the mobile platform,
the linear actuators are suitable for moving the mobile platform in translation along an axis and for orienting the mobile platform in rotation about two axes,
wherein each linear actuator includes:
a first portion connected to the mobile platform by a universal joint,
a second portion connected to the carrier by a pivot connection,
a motor, and
a screw and nut joint interconnecting the first and second portion,
the universal joint of each actuator is suitable for preventing rotation about an axis of the screw and nut joint, such that rotational actuation of a screw or nut by the motor causes a translational movement between the first and the second portion.
2. The device according to claim 1 , wherein the linear actuators are suitable for moving the mobile platform between a stacked position and at least one operational position, and the carrier and the mobile platform are adapted such that, in the stacked position, the mobile platform bears against the carrier at three support points respectively adjacent to each linear actuator.
3. The device according to claim 2 , wherein the mobile platform and the carrier are adapted to establish, in the stacked position, three sphere-chute type connections between the mobile platform and the carrier, the axes of the sphere-chute connections not are parallel to each other.
4. The device according to claim 3 , wherein the three sphere-chute connections are evenly distributed over a circle, the axes of the chutes extending radially relative to the circle.
5. The device according to claim 2 , further comprising a launch holding device suitable for holding the mobile platform, in the stacked position, against the carrier during launch of the spacecraft.
6. The device according to claim 2 , the device further is dimensioned to allow, in the stacked position, a transmission of greater forces via the support points than via the linear actuators.
7. The device according to claim 6 , wherein each universal joint comprises at least one flexible strip suitable for limiting the forces that are transmitted from the platform to the corresponding linear actuator.
8. The device according to claim 1 , wherein the actuators are arranged, relative to the carrier and to a receiving platform, such that each among the carrier and the platform are symmetrical with respect to a central symmetry.
9. The device according to claim 1 , wherein each screw/nut joint is formed by a roller screw.
10. The device according to claim 9 , wherein the roller screw comprises: a screw, comprising a shank and a threaded rod; a threaded nut mounted on the threaded rod; and a sheath extending around the screw and the nut and housing a lubricant, the sheath comprising:
a first sheath portion connected to the nut and covering a free end of the threaded rod of the screw, the first sheath portion is closed at one end, said closed one end is located at the free end of the threaded rod,
a fixed second sheath portion covering the shank of the screw,
a third sheath portion slidingly mounted on the second sheath portion, and
a fourth sheath portion connected to the nut, and extending from the nut to the shank of the screw so as to partly cover the third sheath portion,
wherein the third and fourth sheath portions are adapted to prevent escaping of lubricant from the sheath.
11. A method for deploying the device according to claim 1 , the device is mounted on a satellite, and initially is in a stacked position in which the mobile platform is resting against the carrier,
the method comprising:
controlling each linear actuator so as move the mobile platform in translation away from the carrier, from an initial stacked position in which the mobile platform is resting against the carrier, and
controlling each actuator to orient the platform in at least one predetermined direction.
12. A non-transitory computer-readable storage having stored thereon a computer program, comprising code instructions, the computer program is loadable into a processor and adapted to cause the processor to carry out, when the computer program is run by the processor, the method according to claim 11 .