Bicycles and motorcycles are widely-used transportation/recreation vehicles and an unstable platform. Compared with passenger vehicles, active safety technology is less developed for bicycle/motorcycle systems and yet it is urgently needed. The project will build a theoretical and algorithmic foundation for the bicycle-based dynamic balance modeling and control for safety enhancement. Specifically, the principal investigator plans to develop (1) A human/bicycle/environment (HBE) interaction modeling scheme; (2) human-centered active safety control; and (3) “smart bicycle” systems design and testing.