﻿ MotionDesigner Reference & User Interface > Motion Laws / Cam-Laws for Segments > Constant-Velocity

# Motion-Law: Constant-Velocity

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

This is a Polynomial motion type.

Motion-Description

 The Velocity is constant for the period of the segment-width.

Motion-Values

You CAN control the:

 Start-Position The Start-Position usually flows from the End-Position of the Start-Velocity The Start-Velocity usually flows from the End-Velocity of the Previous-Segment

You CANNOT control the:

 End-Position The End-Position is a calculated from the Start-Position, Start-Velocity, and Segment-Width End-Velocity The End-Velocity is equal to its Start-Velocity Start Acceleration = End-Acceleration = 0 Start-Jerk = End-Jerk = 0

Segment Parameters

 None

Segment-Range

 None

### Example - Velocity Continuity

 1.Use the Motion-Law Selector to change the 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 Flow / Match - see image The Velocity at the Start of the Selected-Segment is now forced to be equal to the Velocity at the End of the Previous-Segment. The Start Velocity becomes read-only. 2.Edit the End Velocity You should see that the Start-Velocity is equal to the End-Velocity. Blend-Point Editor: Velocity Equal at Blend-Point. Smooth Flow of Velocity at Blend-Point Equal Gradients of Position Graph at Blend-Point

### Example 2 - VELOCITY DIS-CONTINUITY

Definition of a Motion Dis-continuity:

The motion-values change instantly, such that there is a step between two adjacent motion-values. The motion-discontinuity is associated with a motion-derivative. E.g.: A motion has a Velocity discontinuity

A Velocity discontinuity is not recommended, of course. There is infinite acceleration at the Velocity discontinuity - which is mechanically not possible. A Velocity discontinuity puts a kink in the Position graph.

An example of a Velocity Dis-Continuity.

 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.