Electromagnetic attachment mechanism

An electromagnetic attachment mechanism adapted for interfacing with a manipulator arm of a remote manipulator system, said attachment mechanism comprising:

• a housing with a base plate at one end thereof;
• a pair of electromagnets mounted in said housing, each said electromagnet comprising a U-shaped magnetic core with pole pieces at the ends thereof and a plurality of coils wound about said magnetic core between said pole pieces, said base plate having openings therethrough which are sized to accommodate said pole pieces;
• a spring suspension system having a spring bias mounting said electromagnets in said housing with the pole pieces exposed by the openings in said base plate and adapted for movement through said openings when attracted to a magnetic strike plate included in a grapple fixture affixed to a target object in proximity to the attachment mechanism;
• means on said housing for maintaining said pole pieces in spaced relation to said strike plate when the base plate of the housing is directed by said remote manipulator system into engagement with said grapple fixture to thereby establish a gap between the pole pieces and the strike plate;
• an individual control circuit for each electromagnet;
• first and second power sources connectable to said individual control circuits, respectively, for energizing said coils whereby said electromagnets exert an attractive force on said strike plate when in proximity thereto to overcome the spring bias of said spring suspension system and to cause said pole pieces to move through said base plate openings and said gap to contact and grip said strike plate and thereby impose a preload force of predetermined magnitude between said pole pieces and said strike plate;
• preload sensor means in each said individual control circuit for detecting the movement of the pole pieces of the electromagnet controlled thereby and for generating an electrical output signal indicative of the preload force thereby established;
• a back-up battery pack connected in each said individual control circuit as a redundant power source for each electromagnet;
• voltage sensor means in each said individual control circuit for sensing and providing a voltage drop signal for a voltage drop below a predetermined voltage level of the one of said power sources connected to said individual circuit;
• and means responsive to said voltage drop signal to automatically connect the battery pack to energize the electromagnet coils.

An electromagnetic attachment mechanism adapted for interfacing with a manipulator arm of a remote manipulator system, said attachment mechanism comprising:

• a housing with a base member at one end thereof;
• at least one electromagnet mounted in said housing on said base member, each said electromagnet comprising a magnetic core with pole pieces at the ends thereof and a plurality of coils comprising at least one holding coil and a pull-in coil wound about said magnetic core between said pole pieces;
• a spring suspension system mounting each said electromagnet in said housing on said base member with at least one pole piece of each said electromagnet exposed to the exterior of said housing and adapted for movement exteriorly of said housing when attracted to a magnetic strike plate in a grapple fixture affixed to a target object in proximity to the attachment mechanism;
• means on said housing for maintaining the pole pieces in spaced relation to said strike plate when said base member of the housing is directed into engagement with said grapple fixture to thereby establish a gap between said pole pieces and said strike plate;
• means for energizing said coils whereby each said electromagnet exerts an attractive force on said strike plate when in proximity thereto to cause at least one of the pole pieces of each electromagnet to move through said base member to contact and grip said strike plate and thereby impose a preload force of predetermined magnitude between said pole pieces and said strike plate;
• and
• means responsive to said preload force for automatically de-energizing the pull-in coil of each said electromagnet when said preload force is established whereby the grip of the target object is maintained solely by the attractive force of the holding coil.

An electromagnetic attachment mechanism, comprising:

• a housing;
• at least one electromagnet mounted in said housing, said electromagnet comprising a magnetic core with pole pieces at the ends thereof and a plurality of coils wound about said magnetic core between said pole pieces;
• a spring
• suspension system having a spring bias mounting said electro-magnet in said housing with the pole pieces exposed for movement when attracted to a ferrous strike plate affixed to a target object in proximity to the attachment mechanism;
• means on said housing for maintaining said pole pieces in spaced relation to said strike plate when said housing is directed into engagement with said target object to thereby establish a gap between said pole pieces and said strike plate;
• means for energizing said coils whereby said electromagnet exerts an attractive force on said strike plate when in proximity thereto to overcome the spring bias of said spring suspension system and to cause said pole pieces to move through said gap to contact and grip said strike plate.

The method of attaching a grapple fixture to a target object comprising the steps;

• carrying on a space vehicle a manipulator arm having a magnetic attachment mechanism;
• magnetically gripping the grapple fixture with the attachment mechanism;
• carrying on the grapple fixture fastening bolts having slotted heads;
• carrying on the attachment mechanism alignment pins having drive tips which cooperatively engage the slotted heads of fastening bolts;
• maneuvering the space vehicle and the manipulator arm to place the grapple fixture in the desired proximity to the target object;
• and
• driving the alignment pins in a selected direction of rotation to engage the slotted heads of the fastening bolts and, thereby, driving the fastening bolts into accommodating threaded bores provided in the target object.