Walkabouts

An example of straight legged walking on the HRP-4C robot. Most humanoids have constantly bent knees, and this gives them some leeway to handle vertical forces throughout the stride. Real humans do this by having a curved spine which is flexible, and this robot presumably has something comparable at the waist section.

If you pause the video as the leg is about to be lifted you can see that - unusually for most humanoids - there is a separate toe section which facilitates the push off.

Humans are the only primates who routinely walk upright, and it turns out that being able to do this efficiently requires pretty accurate sensing and motion control, which is why we're now only just beginning to see really human-like walking in robots.

I'm not expecting there to be practical uses of large humanoids like this in the near future, simply because of their large complexity and cost, although in the longer term assuming that current technology trends continue a humanoid form seems to be considered desirable and would fit best with existing infrastructure.