Constant-Velocity Cam-Law, Motion-Law

Constant-Velocity : is a 'Polynomial' Motion-Law.

Note: You can use the Flexible-Polynomial motion-law to make a Constant-Velocity motion-law, You can specify it in two different ways:

by specifying positions or
by specifying the velocity.

See Flexible-Polynomial Law for more information.

Segment-Editor AND Blend-Point Editor

CAN specify the:

Position at the START of the segment.
Velocity at the START of the segment.

The Position and Velocity motion-values usually flow from the START of the Previous-Segment, especially when it is Flexible-Polynomial motion-law.

CANNOT specify the:

Velocity at the END of the segment, because the Velocity at the END must EQUAL the Velocity at the START of the segment!
Position at the END of the segment...

...the Position at the end of the Constant-Velocity segment is a function of the:

oPosition at the START of the segment
oVelocity at the START of the segment

SEGMENT-EDITOR: Control Buttons to specify the Constant-Velocity segment

VELOCITY DIS-CONTINUITY

'Discontinuity' means we allow a 'step' in the Velocity graph. This puts a 'kink' In the Position graph.

1.Click the Constant-Velocity segment to make it the RED Selected-Segment

Open the Segment-Editor

BPE-CB-DoNotFlow

2.De-select the Velocity 'Match' [Flow] Control-Button at the left of the Velocity motion-derivative

BPE-EditEnd

3.Make sure the 'Edit Start' Control Button is active, to the left of the 'Start Velocity' motion-value
^^ SEGMENT-EDITOR: Control Buttons to give a 'DIS-CONTINUITY [STEP] in Velocity with the CONSTANT-VELOCITY motion-law^^

^^ SEGMENT-EDITOR: Control Buttons to give a 'DIS-CONTINUITY [STEP] in Velocity with the CONSTANT-VELOCITY motion-law^^

4.Enter a value in the 'Start Velocity' data box. [see below, 1,480 as an example]

VELOCITY CONTINUITY

1.Click the Constant-Velocity segment to make it the RED Selected-Segment

In the Segment-Editor

BPE-CB-DoFlow

2.Select the 'Match' [Flow] Control-Button at the left side of the Velocity Control

See below: Segment Editor Control-Buttons for the Constant-Velocity Segment with 'flow'

The Start-Velocity Control Button becomes write-only because:

the Velocity at the Start of the Selected-Segment is specified by the Velocity at the end of the Previous-Segment.

The Edit End Control Button becomes write-only because:

the Velocity at the End of the Selected-Segment is equal to the Velocity at the start because it is defined as a 'Constant-Velocity' motion-law.
Segment Editor: Control-Buttons for the CONSTANT-VELOCITY segment with 'flow'

Segment Editor: Control-Buttons for the CONSTANT-VELOCITY segment with 'flow'

BPE-Previous-Segment

In the Segment-Editor:

3.Click the 'Previous' button to make the Previous-Segment become the Selected-Segment.

The Previous-Segment now becomes the Selected-Segment[!]. In this motion, the Previous-Segment happens to be a 'Flexible-Polynomial' motion-law. Thus, you can specify its Velocity at its end: its End-Velocity

4.Enter a value in the 'End-Velocity' data box. [see below, 1,380 in this example].

The End-Velocity of this segment 'flows' to the Next-Segment, which is the Constant-Velocity segment.

Segment-Editor: Flexible-Polynomial Segment and the 'PREVIOUS-SEGMENT' that 'flows' to the CONSTANT-VELOCITY segment.

Segment-Editor: Flexible-Polynomial Segment and the 'PREVIOUS-SEGMENT' that 'flows' to the CONSTANT-VELOCITY segment.


See also: Tutorial 3: Constant-Velocity with Flexible-Polynomial

Motion-Law - Constant-Velocity

Example in image:

The Velocity of the Constant-Velocity Segment is 1380 º/sec.

The Previous-Segment and the Next-Segment are Flexible-Polynomial Motion-Laws.

Application Notes:

For example, a transfer mechanism that makes a transfer to a belt moving at Constant-Velocity.

'On-the-fly' cutting, printing, filling, labeling machines.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd