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Brushless DC Servo Driver K-Cube
Fig. 6.7 Graph of a trapezoidal velocity profile
The
S-curve
profile is a trapezoidal curve with an additional 'Jerk' parameter, which limits
the rate of change of acceleration and smooths out the contours of the motion profile.
Jerk Setting
– This parameter is specified in mm/s
3
and accepts values in the range
0 to 46566139. It is used to specify the maximum rate of change in acceleration in a
single cycle of the basic trapezoidal curve.
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. 6.8 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 jerk (J) until the maximum acceleration (A) is reached.
The axis continues to accelerate linearly (jerk = 0) through segment (2) . The profile
then applies the negative value of jerk 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 jerk value to reach the maximum deceleration (D) and then bring the
axis to a stop at the destination.
velocity
maximum
velocity (v)
time
acceleration (slope) a
J
J
A
D
-J
-J
V
Time
V
elocit
y
1
2
3
4
5
6
7
A -
acceleration
D -
deceleration
V -
velocity
J -
jerk
