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LTS Series Long Travel Stages
is decelerated at ‘a’ so that the final position is approached slowly in a controlled
manner.
Fig. 7.4 Graph of a trapezoidal velocity profile
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 applied in mm/s
3
and is derived from the Bow Index
field as follows:
Bow Value = 2
(Bow Index -1)
within the range 1 to 262144 (Bow Index 1 to 18).
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
Fig. 7.5 Typical S-Curve Profile
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
velocity
maximum
velocity (v)
time
acceleration (slope) a
BI BI
A
D
-BI -BI
V
Velocity
12 3 4 56 7
A - acceleration
D - deceleration
V - velocity
BI - bow index
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