Advanced Micro Controls Inc. SMD17E2 - Page 47

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SMD17E2 User Manual CALCULATING MOVE PROFILES
47
S-Curve Acceleration Equations (continued)
Triangular S-Curve Acceleration (continued)
The value of the Acceleration Jerk parameter can now be easily calculated.
This value represents the ideal Acceleration Jerk parameter value for a triangular S-curve acceleration. Set-
ting the value lower than this will result in a longer acceleration period, while setting the value above this will
result in a trapezoidal S-curve acceleration.
When a
s
= a
c
The above examples assume that you can increase the programmed acceleration value to keep the accelera-
tion time the same. If your constant acceleration value is the maximum your system will allow, then using 
S-curve accelerations will lengthen the time needed to accelerate to your desired speed.
In the case of Triangular S-curve accelerations where the Acceleration Jerk parameter is optimized at 200/t,
the value of “t” must be twice that of the acceleration period when constant acceleration is used. For example,
assume a equivalent constant acceleration of 20,000 steps/sec
2
that is applied for 2.0 seconds. If the accelera-
tion value must remain at 20,000 steps/sec
2
, then the acceleration phase will take 4.0 seconds and the Accel-
eration Jerk parameter should be set to 50 (200/4.0)
j
a
s
t 2
--------= jat=
j
2a
s
t
--------=
Ja
s
100
---------
2a
s
t
--------= j
Ja
100
---------=


Ja
s
t 200a
s
=
J
200
t
---------= Acceleration Jerk parameter = 200 / acceleration time