Question Different movement according to object scale

Hello,

I have modeled the rotary pendulum system and want to learn to maintain vertical balance in this system through ML-agent. A component called "Hinge Joint" was added to the connection to move. However, even with the same 3D model, the pendulum has a different movement depending on the object scale, so I posted this question.





This link is the video for this system for ten times the scale.
https://1drv.ms/v/s!AoJuJvjDVETltW1tJwI1ZKiGWlbh

In the case of such a large object scale, the pendulum moves according to the motor movement of the "Hinge Joint".





https://1drv.ms/v/s!AoJuJvjDVETltW5-bvyZehnoU8H6

In the case of such a small object scale, the pendulum does not move.
I want to ask why this is happening and what should I do to make the pendulum move on a small scale?

Thank You,