Danfoss MCO 305 Design Manual page 47

MCO 305 Design Guide
Limited-Jerk
Understanding Limited-Jerk Movements
Limited-jerk movements are similar to normal Trapezoidal movements except that the user may control the
"gentleness" of the acceleration and deceleration ramps. This allows the user to limit the "jerk" caused by
the "instantaneous" acceleration of a Trapezoidal movement.
Typical applications where limited jerk is required:
– lift
– movement of heavy loads
As an example, the following chart shows the acceleration, velocity, and position curves for a Trapezoidal
movement from one position to another position. The sharp changes in acceleration cause the motor to
experience a "jerk" at the beginning and end of each velocity ramp.
The following chart shows the same movement done using a Limited-jerk movement. Note that the accele-
ration changes are no longer "instantaneous" and that the "corners" of the velocity curve have become
rounded. This will result in a smoother motor movement. It will also require slightly longer to get to the
desired target position because the motor takes longer to accelerate to maximum acceleration.
__ Functions and Examples __
®
MG.33.L4.02 – VLT is a registered Danfoss trademark
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