Ballscrew Inertia Matching

[KEJR]

This goes somewhat beyond the scope of the Power PMAC, and may even extend back to the turbo PMAC, but is there anything in the Delta Tau servo algorithms that aid in tuning ballscrew systems with fairly high inertia mismatches? I'm sizing a ballscrew application (bellows coupling to a motor) for a very simple XY application and have inertia ratio (load / motor) of 6:1. In past experience with other motion controllers this is acceptable but going much more than a 5:1 ratio is usually ill advised for high performance tuning, even with notch filtering. Is this still the case with Power PMAC or are there any DT tricks to improve this? I apologize in advance if this is not the appropriate forum for this type of question. KEJR

[bradp]

Many features of the control loop will definitely help in this situation. The ability to have multiple filters, Seperate position and velocity loop filters, Ability to adjust the servo frequency to optimize the signal to noise ratio, and the ease of modifying our existing structure or creating your own structure. On a ballscrew system where the inertia is constant the resonant frequency should also be constant. In this case the trajectory prefilter will also be a big help. There are some other methods that help in cases of large inertia mismatch. We are looking at these and might have something in the future. For us the problem is finding a rather global solution. In the meantime you might find a solution that works well for your specific application. In this case the ease of adding a custom algorithm will be a helpful.