Motor drive error question
I have a question regarding a rather complex belt driven rotor system that is giving me fits; very intermittent . It is a pretty high mass ~800lbs balanced rotor driven by a large 3 phase PLC. It runs slow (<15RPM max) then slowing when moving to specific positions. The belt is new, steel or fiber reinforced V belt. When it is moving the last few degrees to position, the system logs very many changes of direction entries until it finally settles out. Balance is well within tolerances. The belt tension is set by measuring the gap between the tensioner arm and the mount and is where it was when the old belt was in place. The gap does indicate the tension may be lower than called for, so I plan to add tension to the belt to see if this resolves the problem.
Is it possible the belt tension is such that when moving into position, the new belt has enough play/springiness/something that when the PLC drives, the belt has to "catch up" and then the rotor will slightly overshoot, PLC says drive back (change of direction) drive forward etc. and the rotor exhibits a slowly decaying oscillation. It appears to resemble the behavior of an under-damped PI control system. So, this is really part question, part reasonableness check on my logic with this issue. Any ideas would be great, thanks to all.