Along my PhD thesis, one of the main difficult I faced was the evaluation of the biped locomotion. How can we give a mark to a motion as complex as the biped locomotion involving at the same time the hardware design, the whole body control and dynamics ?
In science we like to explore each parameters one by one and be ensured that they are independent. Concerning the walking, it is not the case raising challenge to evaluate and compare performance both for mechanics design and the control.
I suggest we use this topic to reference interesting work trying to address these challenges.