I am working on getting 4th axis to work. While it does move as commanded, it does so in a visibly jerky way.
At first I thought that it was mechanical issue inside the rotary table, such as rust, poor gear meshing, eccentricity etc. I took off the motor and even the lovejoy coupling. The motor, with the attached resolver etc, is now completely alone, lying on a foam pad on the floor. The way this system works is that the motor has a little tiny toothed belt going to the resolver, wires from resolver go into "Resolver to Quadrature Encoder Converter", and from there into PPMC as an input. The bad news is that even without anything on the shaft, it still moves in a jerky way. What I mean by this is not just vibration, but the fact that it periodically accelerates and decelerates.FASTER-slower-FASTER-slower etc. This shakes the whole motor as it moves. I have a feeling that acceleration happen at predictable angles of the motor shaft. It is not just some random vibration from a poorly tuned feedback loop. I think that it turns faster in some quadrants and slower in some other quadrants. I know several facts: 1) If I apply a constant voltage to the motor, from a DC power supply, the motor turns smoothly like a clock. 2) I believe that at least over a whole number of turns, the resolver is accurate. Say, if I command the RT to move by 360 degrees, it does move by 360 degrees exactly and ends up at the perfect mark./ 3) If I try to apply force to deflect motor shaft, in some positions it is easier to move the shaft in one direction that another. The shaft springs back, since there is a P factor (I and D are 0), but clearly it is harder to turn it in one direction than another. This depends on shaft opsition. >From this, I conclude that this is a feedback based issue, such as the resolver or resolver converter somehow being behind and ahead on reporting its position, which leads to uneven rate of speed. Any ideas? ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
