Can I Use Two Motors/Encoders with Different Steps/Counts Per Revolution to Perform 2-D Moves?Hardware: Motion Control
Problem: I have motors/encoders that have different steps/counts per revolution conected to my PCI/PXI-73xx motion controller. I would like to use them both to perform a circular move however the input is in steps. Solution: This is not a feature that is built into NI-Motion, however it is possible to use motors or encoders with different steps or counts per revolution. There are two different ways to accomplish this. Option 1: Option one will use gearing and will require an unused axis on your motion controller. To accomplish this you will need to setup a dummy open-loop stepper axis. The dummy axis will be the master of the gearing system and the axis with the motor will be the slave. The gear ratio will be set to correct the differences in the motors or encoders. For example, assume axis X moves 5 inches per 10,000 counts and axis Y moves 10 inches per 10,000 counts. To overcome this you will need to set up a third axis, we will call it Y2. Set up axis Y2 as an open loop stepper and as the master to axis Y. Use a gear ratio of 2:1. From this point on use axis X and Y2 in your motion application. When run, the program will move axis X 10,000 counts and axis Y 5,000 counts. Limitations:
Any type of motion can be accomplished using contouring. The problem with contouring is that it can be difficult to produce the contoured profile while maintaining the proper move constraints. To accomplish this will require some algebra and calculus. Related Links: Developer Zone Tutorial: Gearing Settings for Motion Controllers Developer Zone Tutorial: Configuring a Motion Control System Attachments:
Report Date: 08/19/2008 Last Updated: 11/13/2008 Document ID: 4OIC5L6T |
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