﻿ MotionDesigner Reference & User Interface > Motion Laws > Constant-Velocity : Specify Velocity

# Motion-Law: Constant-Velocity

Navigation:  MotionDesigner Reference & User Interface > Motion Laws >

# Motion-Law: Constant-Velocity

### Constant-Velocity Cam-Law, Motion-Law

 This is a Polynomial motion type See also : Constant-Velocity: Specify Two Positions. Motion-Values: You CAN specify its: •Start-Position The Start-Position usually flows from the End-Position of the Previous-Segment   •Start-Velocity The Start-Velocity usually flows from the End-Velocity of the Previous-Segment You CANNOT specify its: •End-Position •End-Velocity •End-Acceleration or End-Jerk The End-Position is a calculated from the: oStart-Position, oStart-Velocity, and Then End-Velocity is (obviously) equal to its Start-Velocity

### VELOCITY DIS-CONTINUITY

Definition of discontinuity: the derivative of the motion-derivative changes instantly, There is an instant change of the motion-value for the motion-derivative.

A step-change in Velocity is not recommended, of course.

A discontinuity in Velocity is also infinite acceleration - mechanically impossible.

A step-change puts a kink in the Position graph.

It is here as an example.

 1.Use the Motion-Law Selector to change a motion-law of a segment to a Constant-Velocity. 2.Click above or below the segment in the motion-graphs. The Constant-Velocity segment is now the Selected-Segment. 3.Open the Blend-Point Editor 4.Set the Match Control-Button to Do Not Match 5.Enter a Start-Velocity value that is not equal to the End-Velocity value. Blend-Point Editor: Velocities at Blend-Point are not Equal Step in Velocity Graph, & Kink(corner) in Position Graph. Step in gradient at Blend-Point in Position-Graph.

### Example continued...

Velocity Continued.

 1.Use the Motion-Law Selector to change a motion-law of a segment to a Constant-Velocity. 2.Click above or below the segment in the motion-graphs. The Constant-Velocity segment is now the Selected-Segment. 3.Open the Blend-Point Editor 1.Set the Match Control Button to Do Flow / Do Match - see image Blend-Point Editor: Velocity Equal at Blend-Point. Smooth Flow of Velocity at Blend-Point Equal Gradients of Position Graph at Blend-Point