Can someone explain what would be the single greatest challenge (from a research perspective) in making such a robot today? For example, is it:<p>1. The sensors?<p>2. The actuators?<p>3. Coming up with accurate dynamical models?<p>4. Solving the models accurately?<p>5. Solving the models efficiently?<p>6. Making the models robust to inaccuracy&#x2F;noise?<p>Yes, I realize all of these are probably hard. What I&#x27;m trying to understand is whether the biggest challenge is coming up with e.g. an accurate (possibly nonlinear) dynamical model, or with <i>solving</i> the model (efficiency&#x2F;accuracy), or with making existing models that are otherwise already completely accurate robust to outside noise, or with the manufacturing aspect (precision), or whatever.