MOTION CONTROL: Load shaft consideration

[Akanimo]

Hi everyone,

Reviewing motion control literature, from what I've gathered from text and mathematical expressions presented in literature, it seems like the mass (and inertia) of the load shaft is not considered. Is this the case?

Thanks in advance.

 

[FvM]

To which literature are you referring? I see all kinds of physical plausible models in literature. Simple first order models where motor and load inertia are transformed to one equivalent term, higher order models with multiple inertia terms and elastic coupling in between. At the end of the day, you have to decide which model is appropriate for your system.

 

[Akanimo]

I believe I need to make my question clearer.

Let's assume a simple application with load shaft and a hollow cylindrical load. The load is fitted to the load shaft through the cylindrical hole on the load. The motor shaft is directly coupled to the load shaft, such that when the motor shaft spins, the load shaft is also made to spin and the load also spins. So the motor shaft, the load shaft and the load spin at the same speed.

For this application, the inertia that the motor would work against as presented in literature would be: load inertia and coupler inertia.

My question is, does the weight (or mass) of the load shaft not matter? Why is the load shaft not considered (or seems not to be considered)?

 

[FvM]

What are you specifically asking? If part of the total drive inertia is magically excluded from the calculations? For sure it's not. At best ignored if its contribution to the dynamic behaviour is very small.