Dwell Motion-Law

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Dwell Motion-Law

Dwell Cam-Law, Motion-Law

Motion Description

Dwell is a Traditional Motion-Law. It is a Polynomial Motion-Law.

The Dwell motion-law has a constant Position, or zero displacement.

By definition, its motion-values for Velocity, Acceleration, and Jerk are zero throughout the Segment-Width.


You CAN control the:

Position at the Start - which usually flows from the Position at the end of the Previous-Segment

You CANNOT control the:

Position at the End  - by definition, it is equal to the Position at its Start

Velocity at the Start or End

Acceleration at the Start or End

Jerk at the Start or End

Segment Parameters




Application Notes:

Use a Dwell when you want a tool to be stationary.

However, Dwell segments are used too frequently.  Why?

The other segments become shorter in duration, and their peak accelerations also increase. Shorter segment are more likely to induce vibration in the mechanism. The Peak Torque of the drive-shaft also increases, and reverses from a positive to a negative torque more rapidly. This can lead to wind-up and over-run of the drive-shaft.


Try not to use a Dwell segment unless you need a tool to be absolutely stationary for at least 20° range of the X-axis.

If the dwell is less than 20°, then. as an alternative, try to delete the Dwell segment. Then, use segments that are before and after the 'dwell' that have zero jerk-values at the Blend-Point that replaces the Dwell segment.