Slower than 2Hz stepping frequency about walk-these-ways

[gmargo11]

Hi @thvhauwe ,

The pretrained policy is only trained with stepping frequency range 2.0 to 4.0, which is specified by the parameters limit_gait_frequency and gait_frequency_cmd_range in https://github.com/Improbable-AI/walk-these-ways/blob/master/scripts/train.py#L157. Training a new policy with both these adjusted, for example to [1.5, 4.0], should work.

You can see how the gait frequency command is converted into a contact target here: https://github.com/Improbable-AI/walk-these-ways/blob/master/go1_gym/envs/base/legged_robot.py#L826

To clarify, is it the case that lower frequency commands are never being sampled when you train, despite changing the Cfg? Or that lower frequencies are being sampled, but the robot is not learning to execute them?

-Gabe

[thvhauwe]

Thnx for replying!

Playing around with the play.py script showed the new policy learned to walk with lower frequency (albeit with some jigging
behaviour of swing legs, likely due to untuned rewards).

The remaining question is how to port this to the real robot. What line has to be changed to change the cmd frequency there?

[gmargo11]

During deployment, the command frequency is computed in go1_gym_deploy/utils/cheetah_state_estimator.py:

Modifying Line 174: cmd_freq = 3.0 will change the frequency in the default mode

Modifying Lines 183-186 will adjust the range of frequencies you can command with the joystick:

if MODE_RIGHT == "step_frequency":
            min_freq = 2.0
            max_freq = 4.0
            cmd_freq = (1 + self.right_stick[1]) / 2 * (max_freq - min_freq) + min_freq

Be sure to use the top right trigger to toggle into mode E (step frequency).