User Manual
Appendix G
GFK-1742F
Jan 2020
Strobe Accuracy Calculations
464
Figure 220: Effective response time delay
Therefore, in the example above, the worst-case error due to acceleration/deceleration
can be expressed as +/- 0.086 degrees (approximately 2 counts) of position or as 62.5
microseconds of delay (given that the initial velocity is 0). Note that the DSM cannot deal
with fractional units and therefore the error will be rounded to the nearest count or user
unit.
The formulas for determining the strobe error due to acceleration/deceleration on a
Digital axis are as follows:
Counts_of_error =
Effective_delay =
Where:
A = Acceleration/deceleration during the strobe event
T
p
= Position sampling period which is 250 microseconds
V
I
= Velocity just before the strobe
Note that the formulas above assume constant acceleration throughout the sampling
period. The formulas for determining the error for the cases where acceleration is not
constant during the sampling period are too complex for the context of this manual.