System inertia 1

[NHPilot]

I have an instrument with a motor driving timing belts which in turn drive various disks with hubs,shafts, bearings, etc. The motor control software needs to know the total system inertia in order to properly control speed.

Can anyone suggest a way to measure actual total intertia for all of the moving parts connected to the motor?
I can remove the motor and have access to the input shaft if that helps. If I can measure the torque required to start the system moving, can this be used to calculate what I'm looking for?

 

[EnglishMuffin]

Answer to last qusetion : No. The minimum torque required to just start the system moving depends on friction only.
One way to check the inertia would be to measure the acceleration for a known torque and calculate the inertia from that. You might be able to estimate the torque from the motor current. If you knew enough about the system stiffness, you could estimate the inertia from the torsional natural frequency. However, the normal approach is to calculate the inertia. Is there any reason you can't do this ?

 

[GregLocock]

One way would be to conduct a full throttle acceleration, then add a known additional inertia (ie a flywheel) to the system, and repeat.



Cheers

Greg Locock