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A seek operation is performed by identifying a seek length of the seek operation and selecting a representation of a deceleration position-velocity profile based on the seek length. Successive demand velocity values are selected during the seek operation by identifying a distance-to-go and a distanc

A seek operation is performed by identifying a seek length of the seek operation and selecting a representation of a deceleration position-velocity profile based on the seek length. Successive demand velocity values are selected during the seek operation by identifying a distance-to-go and a distance-traveled of the seek length, calculating a representation of an acceleration demand velocity based on the identified distance-traveled and a representation of an acceleration position-velocity profile, identifying a representation of a deceleration demand velocity based on the identified distance-to-go and the selected representation of a deceleration position-velocity profile, and selecting the representation of either the acceleration demand velocity or the deceleration demand velocity. The representation of acceleration demand velocity is preferably performed by using a first scaling factors based on the seek length to adjust the identified distance-traveled, and using a second scaling factor based on the seek length to adjust a representation of a demand velocity of a normalized position-velocity profile.

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1. A process of operating a servo system to move a device between positions comprising:accelerating the device during an acceleration phase; decelerating the device during a deceleration phase; and matching maximum demand velocities of the acceleration and deceleration phases to thereby smooth a cro

1. A process of operating a servo system to move a device between positions comprising:accelerating the device during an acceleration phase; decelerating the device during a deceleration phase; and matching maximum demand velocities of the acceleration and deceleration phases to thereby smooth a crossover between acceleration and deceleration of the device. 2. The process of claim 1 further comprising:a) identifying a seek length based on a distance between start and destination positions; b) selecting a representation of a deceleration position-velocity profile based on the seek length; c) identifying a position of the device between the start and destination positions; d) calculating a representation of an acceleration demand velocity for the device for the identified position based on a representation of an acceleration position-velocity profile; e) identifying a representation of a deceleration demand velocity for the device for the identified position based on the selected representation of a deceleration position-velocity profile; f) selecting the identified representation of either the acceleration demand velocity or the deceleration demand velocity; and g) operating the servo system based on the selected representation. 3. The process of claim 2, wherein step (d) is performed by steps of:d1) calculating first and second scaling factors based on the seek length, d2) adjusting the identified position by the first scaling factor, d3) identifying a representation of a demand velocity of a normalized position-velocity profile for the acceleration phase based on the adjusted position, and d4) adjusting the identified representation of the demand velocity based on the second scaling factor. 4. The process of claim 3, wherein the first and second scaling factors are calculated based on quadratic equations.5. The process of claim 3, wherein the first scaling factor is based on andthe second scaling factor is based onAV(SeekLength)2+BV(SeekLength)+CV, where AX, BX, CX, AV, BV and CV are coefficients based on the seek length, and SeekLength is the seek length.6. The process of claim 2, wherein step (d) is performed by scaling identified positions of a representation of a normalized position-velocity profile based on a first scaling factor and by scaling velocities of the representation of the normalized position-velocity profile based on a second scaling factor.7. The process of claim 2, further includingg) repeating steps (c) through (f) for a plurality of positions between the start and destination positions. 8. The process of claim 2, wherein step (f) is performed by steps of:f1) comparing the representations of the acceleration demand velocity and the deceleration demand velocity, and f2) selecting the smaller of the acceleration demand velocity representation and the deceleration demand velocity representation. 9. The process of claim 1 wherein the matching comprises adjusting at least one of the acceleration and deceleration of the device.10. The process of claim 9 wherein the adjusting is based upon a quadratic equation.11. A process of operating a disc drive servo system in a seek mode, the process comprising:obtaining representations of an acceleration position-velocity profile for a head and a deceleration position-velocity profile for the head; matching maximum demand velocities of the representations of deceleration and acceleration position-velocity profiles; and positioning the head on a storage medium in accordance with the matched maximum demand velocities. 12. The process of claim 11 further comprising:a) identifying a seek length based on a distance between start and destination tracks on the storage medium; b) selecting the representation of a deceleration position-velocity profile based on the seek length; c) identifying a track position of the head between the start and destination tracks; d) calculating a representation of an acceleration demand velocity for the head for the identified track position based on the representation of the acceleration position-velocity profile; e) identifying a representation of a deceleration demand velocity for the head for the identified track position based on the selected representation of a deceleration position-velocity profile; f) operating the servo system based on the representation of one of the acceleration demand velocity or the deceleration demand velocity; and g) repeating steps (c) through (f) for a plurality of tracks between the start and destination tracks. 13. The process of claim 12, wherein step (d) is performed by steps of:d1) calculating first and second scaling factors based on the seek length, d2) adjusting the identified track position by the first scaling factor, d3) identifying a representation of a demand velocity of a normalized position-velocity profile for the acceleration phase based on the adjusted track position, and d4) adjusting the identified representation of the demand velocity based on the second scaling factor. 14. The process of claim 13, wherein the first and second scaling factors are calculated based on quadratic equations.15. The process of claim 13, wherein the first scaling factor is based on andthe second scaling factor is based onAV(SeekLength)2+BV(SeekLength)+CV, where AX, BX, CX, AV, BV and CV are coefficients based on the seek length, and SeekLength is the seek length.16. The process of claim 12, wherein step (d) is performed by scaling identified positions of a representation of a normalized position-velocity profile based on a first scaling factor and by scaling velocities of the representation of the normalized position-velocity profile based on a second scaling factor.17. The process of claim 12, wherein step (f) is performed by steps of:f1) selecting the smaller of the acceleration demand velocity or the deceleration demand velocity, and f2) operating the servo system based on the representation of the selected demand velocity. 18. Servo apparatus to move a head in a disc drive, comprising:an actuator responsive to a representation of a demand velocity to move the between tracks; and acceleration/deceleration circuitry configured to provide an acceleration demand position-velocity profile and a deceleration demand position-velocity profile to the actuator in which maximum demand velocities of the profiles are matched to thereby smooth a crossover between acceleration and deceleration of the head. 19. The servo apparatus of claim 18 further comprising:a seek length identifier identifying a seek length between start and destination tracks; a calculator responsive to the identified seek length for calculating a scaling factor; position detection apparatus for identifying a position of the head between the start and destination tracks; first storage apparatus responsive to the identified seek length and to the identified track position of the head to select a representation of a first demand velocity; second storage apparatus responsive to the identified track position of the head and to the scaling factor to provide a representation of a second demand velocity; and a selector responsive to the first and second storage apparatus to select the representation of either the first or second demand velocity. 20. The servo apparatus of claim 19, wherein the calculator is responsive to the identified seek length to calculate first and second scaling factors, and the second storage apparatus stores a normalized acceleration position-velocity table and is responsive to the first scaling factor to scale the identified track position,the second storage apparatus being responsive to the scaled track position to provide the representation of the second demand velocity based on a normalized demand velocity for the scaled track position and the second scaling factor. 21. The servo apparatus of claim 20, wherein the calculator calculates the first and second scaling factors based on quadratic equations.22. The servo apparatus of claim 20, wherein the calculator calculates the first scaling factor based on andcalculates the second scaling factor based onAV(SeekLength)2+BV(SeekLength)+CV, where AX, BX, CX, AV, BV and CV are coefficients based on the seek length, and SeekLength is the seek length.23. The servo apparatus of claim 19, wherein the calculator calculates first and second scaling factors and the second storage apparatus scales the identified track position of the head to a representation of a normalized position-velocity profile based on the first scaling factor and scales corresponding velocities of the representation of the normalized position-velocity profile based on the second scaling factor.24. The servo apparatus of claim 19, wherein the position detection apparatus identifies plural track positions of the head as the head moves from its start to its destination track, and, for each track position,the first storage apparatus contains a plurality of deceleration position-velocity tables each correlating a track position of a head to a velocity through respective deceleration phases for different seek lengths, the first storage apparatus selecting a deceleration position-velocity table based on the seek length and selecting a first demand velocity from the selected deceleration position-velocity table based on the identified track position, and the second storage apparatus scales the identified track position to identify a representation of a normalized demand velocity for the scaled track position, and scales the identified representation of the normalized demand velocity to provide the representation of the second demand velocity. 25. The servo apparatus of claim 19, wherein the selector selects the smaller of the representations of the first and second demand velocities.