Getting Inaccurate Velocity Reading with ValueMotion Primary Software: Driver Software>>ValueMotion SoftwarePrimary Software Version: 4.5 Primary Software Fixed Version: N/A Secondary Software:
Problem: When I use the Velocity Read or RPM functions at low speeds, the functions return incorrect speeds. For example, when I run the motor at 100 RPM, the functions return values like 75 and 130 but never 100. Is there anything that I can do to correct this error? Solution: This is a very common issue with many users. This has to do with the fact that when reading velocity, the sample period takes some discrete amount of time. The board can only detect whole steps and not fractions of steps during the sample period. For example, if the motor went 4.5 steps, then the board would only detect 4 steps and it would calculate a velocity based on that. The 0.5 step would carry over into the next sample period, and the board would think that 5 steps had occurred during that next sample period, because 0.5 step + 4.5 steps = 5 steps. The velocity calculated in the sample period with 4 steps will be different than the velocity calculated in the period with 5 steps, and neither result will be the accurate velocity. The solution to this problem is to average the velocities that are read. Taking an average will get you much closer to the real velocity. Related Links: Attachments:
Report Date: 12/09/1999 Last Updated: 02/14/2002 Document ID: 1S8G161Q |
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