"Now, if we are really to think about robots that would interact with human or move in the human environment, we would need to have those robots not fixed but mobile. So we started to look at mobile manipulation, and that brings a lot of interesting issues in the dynamic of macro mini-structures. The properties of dynamics in relation to reduce effective inertias, redundancy, and all kind of things that were amazingly interesting to analyze and work on. As we pursued this work, we discovered that, “Well, there’s more.” When we got to humanoid robotics we have the branching, complex branching structure, with multiple tasks that need to be simultaneously achieved while maintaining constraints, while maintaining balance, given the fact that these robots are under-actuated. It’s amazing. You have one problem after the other. It’s so rich, so exciting. So that was one line of the work that I was really interested in, dynamic control and control structures."