﻿ MotionDesigner Reference & User Interface > Motion Laws / Cam-Laws for Segments > Triple-Harmonic Motion-Law > Triple-Harmonic: Zero-Jerk-at-Crossover Motion-Law

# Triple-Harmonic: Zero-Jerk-at-Crossover Motion-Law

### Triple-Harmonic: 'Approximate Zero-Jerk at Crossover'

 Crossover : the point at which the Acceleration changes to Deceleration, or vice-versa When Jerk is zero as the acceleration changes from a positive value to a negative value, we say the Motion-Law has Zero Jerk at Crossover. Acceleration changes slowly. When acceleration changes slowly, and it is also near to zero, the velocity also changes slowly. If there is backlash in the mechanical transmission between the follower and the tool, then backlash is traversed as the force changes from a positive action to a negative action. Since the velocity happens to be changing slowly, the impact velocity should also be small, with this motion-law. Note: the Force changes when the total force on the mechanical element changes sign. The force in the system is not only a function of the Motion-Law. The Force may also include: constant, spring, damping and other forces). To use this Motion-Law: 1.Select Triple Harmonic 2.Open the Segment Editor. 3.Edit the Segment Parameters: First Harmonic = Second harmonic = 0.0 Third Harmonic = We calculate the third harmonic for you. Segment Parameters Harmonic Settings that give an Acceleration with Zero Jerk at Crossover Pseudo Zero Jerk at Start, End and at Crossover from 3 Harmonics.