Transducer positioning apparatus with multiple modes of motion

A method, responsive to external position commands, first and second position information signals which provide position information with respect to positions of a transducer apparatus over selected ranges of positions, and a reference position information signal which provides reference position information at discrete positions, for positioning the transducing apparatus relative to a rotating storage medium at a selected position thereon, comprising the steps of:

• producing displacement of the transducing apparatus toward a position indicated by a received external position command in a plurality of different, separately excitable control modes which each correspond to a different discrete range of displacement from the indicated position;
• determining position information from the first and second position information signals;
• determining the velocity of a positioning apparatus;
• combining the position information determined from the first and second position information signals;
• monitoring the reference position information signal at the discrete positions to determine an offset value with respect to position information determined from the first and second position information signals;
• selecting the first position information signal for position determination in response to position information derived from the first position information signal being less than one-half of the combined position information, and selecting the second position information signal for position determination in response to the position information derived from the first position information signal being greater than one-half of the combined position information;
• determining a difference in position between a position indicated by the determined position information and a position indicated by an external position command;
• and
• selecting the control mode for producing displacement of the transducer in response to a discrete range of displacement indicated by the determined difference in position and the determined velocity.

A method for moving a transducing apparatus from a current position to a desired position with respect to a rotating storage medium by positioning apparatus having a plurality of separately excitable ranges of motion, first and second position information signals which provide position information with respect to positions of the transducing apparatus over selected ranges of positions, and a reference position information signal which provides reference position information at discrete positions in response to reference position information stored in the rotating storage medium, the rotating storage medium having a plurality of tracks for the storage of information, and each track containing reference position information, the method comprising the steps of:

• determining parameters associated with the positioning apparatus;
• determining position information from the first and second position information signals;
• combining the position information determined from the first and second position information signals;
• monitoring the reference position information signal at the discrete positions to determine an offset value with respect to position information determined from the first and second position information signals;
• selecting the first position information signal for position determination in response to position information derived from the first position information signal being less than one-half of the combined position information, and selecting the second position information signal for position determination in response to the position information derived from the first position information signal being greater than one-half of the combined position information;
• determining a current position for the transducing apparatus from the selected position information signal;
• determining a distance between the current position of the transducing apparatus and the desired position;
• determining a velocity of the transducing apparatus;
• selecting one of a plurality of modes of motion for the transducing apparatus responsive to the determined distance and velocity;
• and
• advancing the transducing apparatus toward the desired position according to the selected mode of motion, the determined distance and velocity, and the determined parameters.

A method for moving a transducing apparatus from current position to a desired position with respect to a rotating storage medium by monitoring position information indicating a position of the transducing apparatus, the position information including first and second position information signals which provide position information with respect to positions of the transducing apparatus over selected ranges of positions, the storage medium having a plurality of tracks for storage of information thereon, each track containing a reference position information signal which provides reference position information at discrete positions, the method comprising the steps of:

• determining position information from the first and second position information signals;
• combining the position information determined from the first and second position information signals;
• monitoring the reference position information signal at the discrete positions to determine an offset value with respect to position information determined from the first and second position information signals;
• selecting the first position information signal for position determination in response to position information derived from the first position information signal being less than one-half of the combined position information, and selecting the second position information signal for position determination in response to the position information derived from the first position information signal being greater than one-half of the combined position information;
• determining current position from the selected position information signal;
• determining a distance between the current position of the transducing apparatus and the desired position;
• determining a velocity of the transducing apparatus;
• selecting one of a plurality of modes of motion for the transducing apparatus responsive to the determined distance and velocity, the modes of motion including a first mode wherein said transducing apparatus is first accelerated to a preselected velocity and thereafter maintained at substantially the preselected velocity for a determined distance greater than a first preselected distance, and in response to the determined distances being equal to or less than the first preselected distance, or the determined velocity being greater than the preselected velocity, decreasing the velocity in discrete steps, and wherein position of the transducing apparatus is determined with respect to every other track;
• a second mode wherein the velocity of said transducing apparatus is decreased in discrete steps for the determined velocity less than the preselected velocity and the determined distance greater than a second preselected distance, and wherein position of the transducing apparatus is determined with respect to every track;
• a third mode wherein velocity of said transducing apparatus is decreased in discrete steps for a determined distance equal to or less than the second preselected distance and greater than a third preselected distance;
• a fourth mode responsive to the determined distance being less than the third preselected distance wherein position of the transducing apparatus is controlled in response to an integration and differentiation of the position information, as well as the position information;
• advancing the transducing apparatus toward the desired position according to the selected mode of motion;
• and
• changing the selected mode of motion based upon the distance and velocity determinations of the transducing apparatus associated with each of the modes of motion.

Apparatus responsive to external position commands for positioning a transducing apparatus relative to a rotating storage medium at selected positions thereon, the positioning apparatus including encoding apparatus for producing first and second position information signals which provide position information with respect to positions of the transducing apparatus over selected ranges of positions, means for generating a reference position information signal which provides reference position information at discrete positions, and externally commutated transducer positioning apparatus having commutation points associated therewith, the positioning apparatus further comprising:

• a first means for determining the commutation points for the externally commutated transducer positioning apparatus;
• a second means for determining position information from the first and second position information signals;
• a third means for combining the position information determined from the first and second position information signals;
• a fourth means for monitoring the reference position information signal at the discrete positions to determine an offset value with respect to the position information determined from the first and second position information signals;
• a fifth means for selecting the first position information signal for position determination in response to the position information derived from the first position information signal being less than one-half of the combined position information, and selecting the second position information signal for position determination in response to the position information derived from the first position information signal being greater than one-half of the combined position information;
• a sixth means for determining maximum and minimum values of the first and second position information signals produced by the position encoding apparatus;
• a seventh means for determining position from the selected position information signal;
• and
• control means, responsive to the external position commands, and said first, second, third, fourth, fifth, sixth and seventh means for positioning the transducing apparatus at the selected positions relative to the rotating storage medium by selectively commutating the transducer positioning apparatus.