@article{son2006ultrasonic, title = {An ultrasonic standing-wave-actuated nano-positioning walking robot: piezoelectric-metal composite beam modeling}, author = {Son, Kwon Joong and Kartik, Venkataraman and Wickert, Jonathan A and Sitti, Metin}, journal = {Journal of vibration and control}, volume = {12}, number = {12}, pages = {1293--1309}, publisher = {Sage Publications}, year = {2006}, doi = {} }