Requesting #4843 Motor Parameters (20.4:1 Metal Gearmotor 25D HP 12V) for PID Control

[Mohamed]

Hallo,

I am using the Pololu 20.4:1 Metal Gearmotor 25D HP 12V #4843 Motor in a project of PID Speed Controll, driven by the Single BTS7960 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 (Kt)
• Back EMF constant (Kb)
• Rotor inertia (J)
• Gearbox inertia (J)

Could you please share these or any estimated values?

regards!
Mo

[PatrickM]

Hello.

Thank you for your interest in our motors. Many of the parameters you are interested in can be derived from the performance curves in our 25D 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:

#2214 "100:1 Micro Metal Gearmotor HP 6V with Extended Motor Shaft"

Hello. You can find information about many of these parameters, on the product page and in the datasheet for our Micro Metal Gearmotors (which you can find under the resources tab). The datasheet also includes performance curves for the motors. In the datasheet specs and performance curves you can find the rated/nominal voltage, maximum efficiency, no-load speed, no-load current, and stall torque. In the rest of this post, I will tell you how you can derive or estimate the values that are not e…

Unlike the motor discussed in that forum post, the inductance of our 25D HP 12V motors is about 1.4mH.

Also, for moment of inertia calculations, the output shaft on our 25D 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 making 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