﻿ MotionDesigner Reference & User Interface > Motion Laws / Cam-Laws for Segments > CV Inverse Crank [Special]

# CV Inverse Crank

### CV (Constant-Velocity) Inverse Crank

Motion-Description

 We can explain this motion-law if we project the motion of a Point, that is at the end of a rotating Crank, onto a Line. When a Crank rotates with Constant angular velocity, the motion of a Point that we project onto any Line is Simple-Harmonic-Motion. When the Crank rotates with the CV-Inverse-Crank motion-law, the motion of a Point that we project onto a particular Line is Constant Linear Velocity.

#### Motion-Values

 Start Position - control with the Segment-Parameters - see below. End Position - control with the Segment-Parameters - see below.

You CANNOT control the:

 Start Velocity and End Velocity Start Acceleration and End Acceleration Start Jerk and End Jerk The actual velocity, acceleration, and jerk values, and the distance the Point moves along the Line are a function of the: •Segment-Width •Length of the Rocker/Crank •Segment-Parameters

Segment Parameters

 Typical Segment-Parameters for the CV Inverse-Crank motion-law Svchematic to help you understand how to use the CV Inverse Crank motion-law. The Segment-Parameters are ANGLES: Min Vel (Minimum Velocity) The Angle relative to the Base-Value angle that you control with the Motion-Dimension FB at which the Crank rotates with Minimum-Velocity. Rel Start (Relative Start) The angle, relative to the angle you control with Min Vel, at which Point starts to move along the Orange Line with Constant-Velocity. Rel End (Relative End) The angle, relative to the angle you control by Min Vel , at which Point ends the move along the Orange Line with Constant-Velocity. Note: The Crank rotates Counter-Clockwise when Rel. Start is Negative and Rel. End is a Positive. The Crank rotates Clockwise when Rel. Start is Positive and Rel. End is Negative.

Segment-Range

 Start-Range End- Range 0 ≤ Start-Range < End-Range ≤ 1

Example motion with 2 x CV Inverse-Crank motion-laws

EXAMPLE

Two CV Inverse Crank segments in one Motion.

Segment : Constant-Velocity Inverse-Crank

X-axis : 0 to 90º

Segment Parameters are:

Angle of Minimum Velocity = 90º

Relative Start Angle = –30º

Relative End = 30º

With these Parameters:

X-axis = 0º ; Y–axis = 60º.

X-axis =90 ; Y–axis = 120º

Segment : Flexible-Polynomial

X-axis : 90 to 180º

Y-axis at Start P=120. V, A, J flow from the end of the Constant-Crank-Velocity Segment.

Y-axis at End 240º

Segment : Constant-Velocity Inverse-Crank

X-axis : 180 to 270º

Segment Parameters are:

Angle of Minimum Velocity = 270º

Relative Start Angle = –30º

Relative End = 30º

With these Parameters:

X-axis = 180º ; Y–axis = 240º

X-axis = 270 ; Y–axis = 300º

Segment : Flexible-Polynomial

X-axis : 90 to 180º

Y-axis P at Start = 300º. V, A, J flow from the end of the Constant-Crank-Velocity Segment.

Y=axis at End = 420º.