Active rotational balancing system for orbital sanders

An apparatus for moving correcting masses to dynamically balance a rotating shaft having an axis, the apparatus comprising:

• a housing, substantially symmetric along each of a first plane perpendicular to the axis, a second plane containing the axis an perpendicular to the first plane;
• a first stepper motor attached to the housing;
• a second stepper motor attached to the housing in opposed relationship to the first stepper motor within the first plane and symmetric to and offset from the second plane such that the mass of the first stepper motor will counterbalance the mass of the second stepper motor upon rotation of the shaft;
• a first correcting mass assembly attached to the housing, the first correcting mass assembly configured to engage the first stepper motor such that rotation of the first stepper motor will move a first center of gravity along a first line extending radially from the axis and perpendicular to the second plane;
• and
• a second correcting mass assembly attached to the housing, the second correcting mass assembly configured to engage the second stepper motor such that the rotation of the second stepper motor will move a second center of gravity of the along a second line extending radially from the axis, perpendicular to the second plane and symmetrically offset from the first plane.

A method for active dynamic balancing of a rotating tool driven by a motor having a shaft, the shaft being supported by a first and second bearing on opposing sides of the motor, the system comprising:

• sensing radial accelerations on the shaft;
• generating an acceleration signal indicative of the radial accelerations;
• and
• adjusting a correcting mass in a correcting mass assembly responsive to the acceleration signal, the correcting mass assembly configured to rotate with the shaft and to move at least one correcting mass radially to the shaft.

A software program stored on a machine readable medium, the program configure for active dynamic balancing of a rotating tool driven by a motor having a shaft, the shaft being supported by a first and second bearing on opposing sides of the motor, the system comprising:

• a first script configured to sense radial accelerations on the shaft;
• a second script configured to generate an acceleration signal indicative of the radial accelerations;
• and
• a third script configured to adjust a correcting mass in a correcting mass assembly responsive to the acceleration signal, the correcting mass assembly configured to rotate with the shaft and to move at least one correcting mass radially to the shaft.