Linear dc motor vibration controller

For use with a space-deployed structure that is subject to vibrational movement, a system for imparting a controlled dampening force to said structure, so as to counter said vibrational movement comprising:

• a linear direct current motor having a primary winding and a rectilinear secondary actuator element magnetically coupled therewith, so that, in response to the generation of a magnetic field by said primary winding, there is effective rectilinear oscillatory motion between said primary winding and said secondary actuator element;
• wherein
• one of said primary winding and said rectilinear secondary actuator element is attached to said structure while the other of said primary winding and said rectilinear secondary actuator element is freely translatable with respect to said structure, whereby, in response to the generation of a magnetic field by said primary winding, there is relative movement between the other of said primary winding and said rectilinear secondary actuator element and said structure, so that a vibrational movement compensating force, against which said structure reacts, may be generated by said linear direct current motor, to thereby impart a controlled dampening force to said structure, and wherein
• relative movement between said other of said primary winding and said rectilinear secondary actuator element and said structure is controlled exclusive by controlled magnetic field interaction between said primary winding and said rectilinear secondary actuator elements.

A method of controlling vibration of a mechanical structure comprising the steps of:

• (a) coupling to said mechanical structure a linear direct current motor having a primary winding and a secondary member rectilinearly movable with respect to said primary winding, such that one of said primary winding and said secondary member is fixed with said mechanical structure and the other of said primary winding and said secondary member is movable with respect to said structure so as to be able to impart thereto a controlled linear inertial input by its movement;
• (b) applying a prescribed force input representative signal to said primary winding so as to cause the movable one of said primary winding and said secondary member to undergo a prescribed oscillatory rectilinear movement with respect to said mechanical structure and thereby effectively compensate for destabilizing vibrations of said mechanical structure resulting from force inputs other than said prescribed force input;
• (c) monitoring the relative movement between said primary winding and said secondary member on the rectilinear travel path of the movable one thereof and generating a signal representative of the location of displacement between said secondary member and said primary winding;
• (d) controlling the energization of said primary winding in accordance with the signal generated in step (c);
• (e) monitoring the displacement between said primary winding and said secondary member on the travel path of the moveable one thereof and measuring the length of time that the displacement between said primary winding and said secondary member is effectively positioned to one side of a predetermined location on said travel path and measuring the length of time that the displacement between said primary winding and said secondary member is effectively positioned to a second side of said predetermined location;
• and
• (f) adjusting the energization of said primary winding in accordance with a difference in the length of time measurements carried out in step (e) over a prescribed time interval in excess of the period of the lowest frequency of oscillation of said prescribed force input representative signal.

For use with a structure that is subject to vibrational movement, a method for imparting a controlled dampening force to said structure so as to counter said vibrational movement comprising the steps of:

• (a) providing a moveable means to be translated in an oscillatory movement with respect to said structure and thereby impart to said structure a vibrational movement compensating force against which said structure reacts, so that the vibrational movement thereof may be effectively countered by the controlled movement of said means;
• and
• (b) providing, at a location on said structure whereat said vibrational movement may occur, a rectilinear travel path of said moveable means to be translated therealong in an oscillatory manner;
• (c) imparting a controlled force to said moveable means so as to cause said moveable means to oscillate along said rectilinear travel path;
• and
• wherein one of said movable means and said rectilinear travel path comprises a winding of an electric motor and the other of said means and said rectilinear travel path comprises a linear magnetic field responsive element magnetically interacting with said winding of said electric motor, so that said winding may impart a force to said element, and wherein
• the oscillatory translation of said moveable means is controlled exclusively by controlled magnetic field interaction between said winding and said linear magnetic field responsive element.