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Can I Specify Acceleration and Velocity for a Contoured Move?

Primary Software: Driver Software>>NI-Motion/FlexMotion
Primary Software Version: N/A
Primary Software Fixed Version: N/A
Secondary Software: N/A
Hardware: Motion Control>>Controllers>>PCI-7344

Problem:
How can I specify acceleration, velocity, and deceleration for a contoured move when the trajectory generator on the motion controller is not used during a contoured move? 

Solution:
Acceleration and velocity cannot be directly specified for a contoured move. A contoured move creates a cubic spline based on position points declared by the user in the form of an array. The contouring algorithm maps a smooth curve between the contour points that the user specifies. The time interval between points is based on the Requested Interval input.


With each loop iteration of the PID controller, the motion controller passes the next cubic-spline-generated position point to the motor.  Given each new instantaneous step input, the controller then tries to attain this new position given the limitations of the motor’s inertia and the power available from the amplifier.

For example, the following figure illustrates a simple contoured move between five points, with a Requested Interval of 10 milliseconds. The position array in this example is [0, 16, 14, 7, 9]. Notice that the actually path is a smooth curve created by the cubic spline algorithm.




Related Links:
Support: NI-Motion User Manual
Developer Zone Tutorial: Motion Control Technical Library
KnowledgeBase 3889JV4I: Why Does Motion Assistant Exceed Velocity Constraints when Running a Contoured Move?

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Report Date: 10/15/2007
Last Updated: 01/16/2009
Document ID: 4EEJKGQ7

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