Prior to this, he was Principal Scientist at the Palo Alto Research Center (formerly Xerox PARC) where he established a group developing modular self-reconfigurable robots. His group has demonstrated modular robots that can form different shapes, jump, ride tricycles, climb stairs, poles and fences, manipulate objects and reassemble themselves after being kicked into pieces. His other research interests include biologically inspired mechanisms, flying robots and meso-scale MEMs devices.