1. Which field bus/motion bus offers the fastest cycle time?
EtherCAT, with the AKD, can update at 250nS cycle time. That’s 4000Hz. Also, with interpolated position mode, you can delivery data at a slower rate and the drive will calculate the missing data points to give a 4000Hz position update.
2. Which control method is best for synchronization of a large number of axes with tightly coordinated motion?
EtherCAT hardware delivers data to each drive in tandem so the data packet has to pass thru all drives, I/O, etc and then return back the same way. Depending on the EtherCAT controller, you can update 32+ drives in a 1mS cycle time.
3. Which bi-quad filter configuration is most forgiving?
LeadLag filter is the most forgiving. As the amplitude of your system’s resonance/anti-resonance changes (because of belt tension, stiffness, etc) this type of filter will “self adjust” in amplitude to compensate.
4. When creating a "Plant" Bode plot, what injection point do you like best?
Traditional Plant bode plot is current injection in an attempt to create a bode plot with as little influence, from the drive, as possible. The AKD can calculate the Plant bode plot with either.
5. What feedback type has the highest resolution (including interpolation if possible)?
Resolver is read with an analog A to D converter and can be interpolated to 24 bits/rev 2048 PPR. Comcoder can not be interpolated so it’s fixed at 8192 count/rev or 13 bit/rev 2048 PPR. Heidenhain & Hengstler use analog SINE/COS signals and can be interpolated to 27 bit/rev. SFD is resolver feedback that is interpolated in the motor to 24 bit/rev. The data is transfered to the drive over a high speed synchronous serial link.
The AKD autotune’s target can be set by Gain margin and by Phase margin. There is no limit to how high a bandwidth the Autotune can calculate but the true max bandwidth is dependent on the mechanical stiffness, resonance, etc.
7. What kind of filters would you expect an "Autotune" to be able to configure to achieve this bandwidth?
Vibration control is a complex problem; the solution will differ depending on the specific type of vibration encountered. AKD design tools enable the user to specify multiple filter types and determine where they are placed in the velocity loop. AKD ‘s frequency analysis tools that allow for different excitation modes giving the user the ability to measure and characterize different systems. The flexibility of the AKD platform both in design and measurement allows the user to solve a wide variety of vibration problems.
8. When creating a Bode Plot, what excitation type can be used?
While the Autotune can only use current injection, the bode plot tool can use all above and include “stability motion” to exclude stick-slip and/or backlash.
