Again, strain wave gearing (as an approach, including electric motors with high specific power) is lighter than using hydraulics, overall. The same is true for planetary roller screws. This is true regardless of scale. Hydraulics are used for other reasons than maximum performance physically achievable.
Boston Dynamics decreased the weight of their hydraulics system by 3d printing hydraulic channels in the skeleton. That’s expensive, and planetary roller screws are still better if done properly.
Again, strain wave gearing (as an approach, including electric motors with high specific power) is lighter than using hydraulics, overall. The same is true for planetary roller screws. This is true regardless of scale. Hydraulics are used for other reasons than maximum performance physically achievable.
Boston Dynamics decreased the weight of their hydraulics system by 3d printing hydraulic channels in the skeleton. That’s expensive, and planetary roller screws are still better if done properly.