[2] Collins, S., Ruina, A., Tedrake, R., Wisse, M.: 
Efficient bipedal robots based on passive dynamic walkers. Science 307 (2005), 1082-1085. 
DOI 10.1126/science.1107799 
[3] Garcia, M., Chatterjee, A., Ruina, A., Coleman, M.: 
The simplest walking model: Stability, complexity, and scaling. J. Biomech. Engrg. 120 (1998), 2, 281-288. 
DOI 10.1115/1.2798313 
[4] Goswami, A., Thuilot, B, Espiau, B.: Compass-like biped robot Part I: Stability and bifurcation of passive gaits. IINRIA Res. Rep. No. 2996, 1996.
[5] Goswami, A., Thuilot, B., Espiau, B.: 
A study of the passive gait of a compass-like biped robot: Symmetry and chaos. Internat. J. Robotics Res. 17 (1998), 12, 1282-1301. 
DOI 10.1177/027836499801701202 
[6] Grizzle, J. W., Abba, G., Plestan, F.: 
Asymptotically stable walking for biped robots: Analysis via systems with impulse effects. IEEE Trans. Automat. Control 46 (2001), 1, 51-64. 
DOI 10.1109/9.898695 | 
MR 1809465 | 
Zbl 0992.93058 
[7] Hiskens, I.: Stability of hybrid system limit cycles: Application to the compass gait biped robot. In: Proc. IEEE Conference on Decision and Control, Orlando 2001.
[8] Holm, J. K.: Control of Passive Dynamic Robots Using Artificial Potential Energy Fields. M. S. Thesis, Univ. Illinois Urbana-Champaign 2005.
[9] Holm, J. K., Lee, D. J., Spong, M. W.: Time scaling for speed regulation in bipedal locomotion. In: Proc. IEEE Conference Robotics Automation, Rome 2007, pp. 3603-3608.
[10] Ikemata, Y., Sano, A., Fusimoto, H.: Analysis of stable limit cycle in passive walking. In: SICE Anual Conference, Fubukui 2003, pp. 117-122.
[11] Kim, J., Choi, C., Spong, M. W.: Passive dynamic walking with symmetric fixed flat feet. In: Proc. IEEE International Conference on Control and Automation, Guangzhou 2007, pp. 24-30.
[12] Kuo, A. D.: 
Stabilization of lateral motion in passive dynamic walking. Internat. J. Robotics Res. 18 (1999), 9, 917-930. 
DOI 10.1177/02783649922066655 
[13] Kurz, M. J., Judkins, T. N., Arellano, C., Scott-Pandorf, M.: 
A passive dynamic walking robot that has a deterministic nonlinear gait. J. Biomech. 41 (2008), 6, 1310-1316. 
DOI 10.1016/j.jbiomech.2008.01.007 
[14] Kurz, M. J., Stergiou, N.: 
An artificial neural network that utilizes hip joint actuations to control bifurcations and chaos in a passive dynamic bipedal walking model. Biolog. Cybernet. 93 (2005), 3, 213-221. 
DOI 10.1007/s00422-005-0579-6 | 
Zbl 1116.92005 
[15] Kurz, M. J., Stergiou, N.: 
Hip actuations can be used to control bifurcations and chaos in a passive dynamic walking model. J. Biomech. Engrg. 129 (2007), 2, 216-222. 
DOI 10.1115/1.2486008 
[16] Lin, X., Ding, Y., Shen, M., Li, S.: Feedback stabilization of unstable periodic orbits for chaotic passive compass-like biped robot. In: Proc. 7th World Congress on Intelligent Control and Automation, Chongqing 2008, pp. 7285-7290.
[18] McGeer, T.: Passive walking with knees. In: Proc. IEEE Conference on Robotics and Automation, Cincinnati 1990, pp. 1640-1645.
[19] Miller, D. J., Stergiou, N., Kurz, M. J.: 
An improved surrogate method for detecting the presence of chaos in gait. J. Biomech. 39 (2006), 15, 2873-2876. 
DOI 10.1016/j.jbiomech.2005.10.019 
[21] Parker, T. S., Chua, L. O.: 
Practical Numerical Algorithms for Chaotic Systems. Springer-Verlag, New York 1989. 
MR 1009561 | 
Zbl 0692.58001 
[22] Seydel, R.: 
Practical Bifurcation and Stability Analysis. Second edition. Springer-Verlag, New York 1994. 
MR 1314200 
[23] Spong, M. W.: Passivity based control of the compass gait biped. In: Proc. World Congress of IFAC, Beijing 1999, pp. 19-24.
[24] Spong, M. W., Bhatia, G.: Further results on control of the compass gait biped. In: Proc. IEEE International Conference on Intelligent Robots and Systems, Las Vegas 2003, pp. 1933-1938.
[26] Stergiou, N., Buzzi, U. H., Kurz, M. J., Heidel, J.: Nonlinear tools in human movement. In: Innovative Analysis of Human Movement, Human Kinetics (N. Stergiou, ed.), Champaign 2004.
[27] Wisse, M., Schwab, A. L., Helm, F. C. T. Van der: 
Passive dynamic walking model with upper body. Robotica 22 (2004), 6, 681-688. 
DOI 10.1017/S0263574704000475