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# Calculation of Velocity Profile

IP.com Disclosure Number: IPCOM000111478D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 69K

IBM

## Related People

Fukushima, Y: AUTHOR [+3]

## Abstract

This article describes a method and algorithm of the calculation of velocity profile, which is used as a target velocity of seek operation of the actuator servo. This method can reduce the code size of servo program in the memory of control processor by calculating the target velocity during seek operation instead of Velocity table.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Calculation of Velocity Profile

calculation of velocity profile, which is used as a target velocity
of seek operation of the actuator servo.  This method can reduce the
code size of servo program in the memory of control processor by
calculating the target velocity during seek operation instead of
Velocity table.

Fig.1 shows the example of velocity curve.  If this curve is
given by table, it requires 512 bytes (256 words).  Instead of table,
the next target velocity is calculated using the distance from target
position.  Then coefficients of the regression curve of velocity vs.
distance from target track are stored in the memory.

The calculated curve shows non-linear like Fig.1.  So the
calculation was divided into some ranges of distance from target
track.  For example, Figs.2, 3 and 4 show the regression curve of
Fig.1.  And total result is shown in Fig.5.  In this example, the
target velocity was calculated by following equations and the range
is divided into 3.

3         2

y1 = a1 * x  + b1 * x  + c1 * x + d1

3         2

y2 = a2 * x  + b2 * x  + c2 * x + d2

3         2

y3 = a3 * x  + b3 * x  + c3 * x + d3

y1: target velocity (cyl-0 to 16)

y2: target velocity (cyl-17 to 50)

y3: target velocity (cyl-51 to 255)

a1, b1, c1, d1: coefficients (cyl-0 to 16)

a2, b2, c2, d2: coefficients (cyl-17 to 50)

a3, b3, c3, d3: coefficients (cyl-51 to 255)

In the memory, only 12 words area is required for the
coefficients and the calculation algorithm requires very small
program size.  Following flow chart shows an example of the
calculation algorithm....