Meyer, F., Spröwitz, A., Lungarella, M., & Berthouze, L. (2004). Simple and low-cost
compliant leg-foot system. In 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems
(IROS) (pp. 515-520). Piscataway, NJ: IEEE. doi:10.1109/IROS.2004.1389404.