Research in Dan's group is focused on the application of dynamical systems theory to the design, construction and empirical testing of machines that juggle, run, climb, and in general, interact physically with their environment to perform useful work. Dan and his group seek to probe the foundations of autonomous robotics by reasoning formally about mathematical models that represent the successes and limitations of their physical platforms. They maintain close collaborations with biologists, whose insights about animal mobility and dexterity inspire their thinking and designs.