>> Fig. 2 illustrates the design of the robot and the key parameters, with design rules given in Table II and the experimental robot’s final parameters given in Table III.

There is no Table II :(

Passive Dynamic Walking is interesting. I remember being really impressed by a video of a pair of legs going down a slope without any mechanical force on the "walker" itself to move them, just gravity and friction, I guess. That was back in 2014, probably. It seems like people have kept working on the concept. I have no way to tell though whether the idea really has cough cough legs, or it will just remain an engineering curiosity that can never be put to real work.

I can't really tell from this paper. Robotics is not my expertise (I work on autonomous navigation and decision-making for robots, but I'm not allowed to go anywhere near the robots. Electronics fry when I'm in proximity).

Edit: collection of passive dynamic walking videos:

https://youtu.be/FfKQSUhYjlY?si=9xGPqYwMeUyIwjqu