Changing the Gear Ratio on a Motion Controller During a Move Primary Software: Driver Software>>NI-Motion/FlexMotionPrimary Software Version: 6.1.4 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: Motion Control>>Controllers>>PCI-7340, Motion Control>>Controllers>>PCI-7350
Problem: I am currently using electronic gearing in my motion control application. Whenever I try to change the gear ratio during a move, the motor jumps suddenly and sometimes I receive a following error. Is there any way to change the gear ratio while the motor is moving without this behavior? Solution: The sudden jumping and following errors are expected when changing the ratio for an absolute gearing move. This is because the slave axis will need to accelerate instantaneously to try to catch up to the new position. For instance, if the gear ratio is changed from 2:1 to 3:1 when the master is at position 10,000 and the slave is at position 20,000, the slave will need to jump instantly to position 30,000. Depending on the type of move, this example will most likely not cause a following error, but will show the erratic jumping. If the ratio had been increased to 6:1 instead, the slave would be expected to change from 20,000 to 60,000. The 40,000 count difference is typically enough to cause a following error. This behavior will occur even if you stop the motion before adjusting the ratio. The recommended method for changing the gear ratio during a move is to use relative gearing instead of absolute gearing. Relative gearing will apply the new ratio relative to the current position, preventing the sudden jump and following errors. The Load Gear Ratio VI and the flex_load_gear_ratio function both have parameters to set absolute or relative gearing. This parameter will need to be specified each time the gear ratio is changed. Related Links: Developer Zone Tutorial: Gearing Settings for Motion Controllers Developer Zone Tutorial: Electronic Gearing Motion Control Support Attachments:
Report Date: 10/29/2004 Last Updated: 08/04/2007 Document ID: 3ES6ICKZ |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
