ME 415W - Fall 2005
Satellite Docking Mechanism
Project Overview:
Boeing is the world’s leading aerospace company and the largest combined manufacturer of commercial jetliners and military aircraft. With products in rotorcraft, electronic and defense systems, missiles, rocket engines, satellites, launch vehicles and advanced information and communication systems, the company’s reach extends to customers in 145 countries. Boeing is also one of the largest U.S. exporters.
Boeing is interested in extending the life of satellites being put into service by adding a docking interface to which a service satellite would attach. The entire docking assembly should consist of a capturing device (active half) on the servicing satellite and a corresponding interface on the target satellite (passive half). This mechanism will create cost saving opportunities by utilizing one satellite to extend the working lives of existing satellites instead of replacing them.
Approach
Docking mechanism ideas were generated and then compared in a selection matrix with following criterion: weight, durability, repeatability, satellite misalignment considerations, and ability to lock the degrees of freedom between satellites.
Solution:
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The final optimized design fulfills the objectives of both grabbing the satellite and also latching onto it to prevent movement in both the planar and rotational directions. It also solves the problem of positioning the active satellite to a tight tolerance, as the funnel-shaped opening and the rotational aligning component position and lock the two satellite's into place.
The docking mechanism consists of both a passive component on the target satellite and an active component on the servicing space vehicle. The passive component is a hollow tube with a funneled opening at the entrance and an increased diameter at the far end. The funnel component is larger than the inside diameter of the tube, to allow plenty of offset in the initial positioning process. There are also six holes around the outside of the funnel to place the rotational locking mechanism.
The active half consists of three components: a hollow shaft, a triangular latching device on a cantilevered beam, and a plate with filleted protrusions (not indicated in the CAD models). The beam and latching device sit inside the shaft, with a triangular-shaped end protruding through its corresponding opening in the shaft. The latching arm's initial position is controlled by a spring connected to the bottom of the beam and inside the shaft.
The three protrusions on the outer disc of the active component are 120o apart from each other. The protrusions secure into three of the six possible designed holes that are located on the outer rim of the passive component. The six holes are oriented 60o from each other. This alignment of the protrusions and holes will limit the rotation of the shaft, thus limiting the rotation of the chasing satellite relative to the target satellite.
The docking sequence is as follows:
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Initial Positioning: The active component approaches the target satellite and is guided into position as it passes through the funnel. |
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Docking Sequence: As the shaft passes beyond the funnel, the spring is compressed and the latch is contained within the shaft. |
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Locking Sequence: When the assembly has mated, the latch returns to its initial position, locking the mechanism in place. At this time, the plate on the end of the male shaft locks the device rotationally as the protrusions settle into the corresponding openings. |
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Team Orbital (from left to right):
Design Team Advisor:
Project Sponsor:
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Last Updated: November 30, 2005
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