Requesting Motor Parameters for PID Control – Pololu 4756 & 4746

Support Motor controllers/drivers and motors
1

Hi,

We’re using the Pololu 4756 and 4746 motors in a robotics project with PID control, driven by the Dual TB9051FTG Motor Driver. To model the motors in Simulink, we need some parameters that aren’t listed on the product pages:

  • Resistance (R)
  • Inductance (L)
  • Torque constant (Km)
  • Back EMF constant (Kb)
  • Rotor inertia (J)
  • Friction coefficient (B)

Could you please share these or any estimated values?

Thanks a lot!

2

Hello.

I moved your post to help keep the forum organized.

Many of the parameters you are interested in can be derived from the performance curves in our 37D gearmotor datasheet, which is available on the product page under the “Resources” tab:

This forum post I wrote outlines how you can derive many common parameters, including the ones you mentioned, using the information from the performance curves:

Unlike the motor discussed in that forum post, the inductance of our 12V 37D motors is about 2.3mH.

Also, for moment of inertia calculations, the output shaft on our 37D gearmotors is stainless steel. Calculating the inertia of the output shaft would give you a low-side approximation (since it would not account for the inertia of the gears or armature), so you might also consider using some fraction of the motor weight (available on the product page under the “specs” tab) and the overall dimensions to make a high-side inertia approximation too.

- Patrick

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