Smart materials, advanced electronics and modern control theory have found many applications in the past few decades. This talk presents a brief account of the applications in the author’s research including small piezo devices, smart trim panel for aircraft interior noise reductions, medical devices for physical rehabilitations. The emphasis of the talk will be on the medical devices including mart knee braces, variable resistance exercise devices and smart knee ankle braces. The devices are designed for early gait training of stroke patients, and strength training of people with muscle injuries. Control designs of the above mentioned applications will be briefly discussed.