THORLABS TST101 User Manual page 46

Chapter 6
The S-curve profile is a trapezoidal curve with an additional 'Bow Value' parameter,
which limits the rate of change of acceleration and smooths out the contours of the
motion profile. The Bow Value is specified in mm/s
field as follows:
The Bow Value is applied in mm/s
Bow Value = 2
In this profile mode, the acceleration increases gradually from 0 to the specified
acceleration value, then decreases at the same rate until it reaches 0 again at the
specified velocity. The same sequence in reverse brings the axis to a stop at the
programmed destination position.
Example
1 2
-BI
A
BI
The figure above shows a typical S-curve profile. In segment (1), the S-curve profile
drives the axis at the specified Bow Index (BI) until the maximum acceleration (A) is
reached. The axis continues to accelerate linearly (Bow Index = 0) through segment
(2). The profile then applies the negative value of Bow Index to reduce the
acceleration to 0 during segment (3). The axis is now at the maximum velocity (V), at
which it continues through segment (4). The profile then decelerates in a similar
manner to the acceleration phase, using the Bow Index to reach the maximum
deceleration (D) and then bring the axis to a stop at the destination.
The higher the Bow Index, then the shorter the BI phases of the curve, and
the steeper the acceleration and deceleration phases. High values of Bow
46
3
(Bow Index -1)
within the range 1 to 262144 (Bow Index 1 to 18).
3 4
V
Fig. D.3 Typical S-Curve Profile
Index may cause a move to overshoot.
3
and is derived from the Bow Index
and is derived from the Bow Index field as follows:
5 6
-BI
D
Time
Note
7
A - acceleration
D - deceleration
V - velocity
BI - bow index
BI
HA0333T Rev BK Sept 2015