User manual

Rockwell Automation Publication MOTION-UM003F-EN-P - March 2015 265
Program Appendix C
Very small Jerk rates, that is less than 5% of time, produce acceleration and
deceleration profiles close to rectangular ones, such as the one shown in
Trapezoidal Accel/Decel Time on page 263
.
Calculations are performed when an Axis Move, Change Dynamics, or an MCS
Stop of StopType = Move or Jog is initiated.
IMPORTANT
Higher values of the % of Time result in lower values of Jerk Rate Limits
and, therefore, slower profiles. See the following table for reference.
Table 45 - Velocity versus Jerk
Trapezoidal Velocity
Profile
(1)
(1) The example on page 263 (labeled Trapezoidal Accel/Decel Time) uses a rectangular acceleration profile.
S-shaped Velocity Profile
with 1< = Jerk <100% of
Time
(2)
(2) The example on page 265 (labeled Programmable S-curve Accel/Decel Time, Acceleration Jerk = 60% of Time) uses a trapezoidal
acceleration profile.
S-shaped Velocity Profile
with Jerk = 100% of
Time
(3)
(3) The example on page 266 (labeled S-curve Accel/Decel Time, Backward Compatibility Setting: Acceleration Jerk = 100% of Time)
uses a triangular acceleration profile.
Accel/Decel Jerk in
Units/sec
3
∞
Accel/Decel Jerk in
% of Maximum
NA 0 - 100% NA
Accel/Decel Jerk in
% of Time
0% 1 - 100% 100%
Max Accel
2
Max Velocity
to
∞
Max Accel
2
Max Velocity
VelocityAccelJerk
Time
Time
Time
Programmable S-curve Accel/Decel Time,
Acceleration Jerk = 60% of Time
30% 30%40%
% of Time = 60%