Falling down when deployed in Go1

[dstx123]

I tried to retrain the RMA algorithm using go1 urdf, but found that the robot would tend to lean forward or fall over. Do you have any suggestions for this? The parameter "rl_coeff" is set to 1. Below are the visual results of the two stages. Trained 24,000 rounds in the first phase:

https://github.com/antonilo/vision_locomotion/assets/51892853/f6736bcd-b444-4e28-a7fd-d6f69269d38e

Trained 1200 rounds in the second stage:

https://github.com/antonilo/vision_locomotion/assets/51892853/b76acec5-cacc-401b-8761-5cf9137ef631

result graph:

By the way, what does the parameter "jt_mean_pos" in "Environment.hpp" mean? Will this affect go1's training? And why do the hip joints of robots trained by the RMA algorithm tend to expand? This seems to make the gait appear unnatural.