Prior Scientific ProScan III Manual page 86

ProScan® III Manual
S curve vs. Trapezoidal Accelerations
Step motors for years have been accelerated with a standard trapezoidal acceleration. An
example of a trapezoidal acceleration is shown below: This method of motor acceleration
has a great impact on the performance of the system.
The trapezoidal acceleration causes the stage to jerk as it starts, switches from
acceleration mode to maximum velocity mode, and switches from maximum velocity
mode to deceleration mode. (Note all of the sharp corners on the graph). This can cause
the stage to vibrate and it can increase stage settling time.
The ProScan controller accelerates the stage via the S-curve as shown below.
The S-curve acceleration transitions from starts to stops with smooth accelerations and
decelerations thereby resulting in faster, quiet, and vibration free performance. The stage
can actually be moved faster due to the ramp characteristics of the S-curve. Settling time
is greatly reduced and overall stage performance is enhanced.
© Prior Scientific Instruments Ltd Version 1.12 June 2017 Page 84