P. Allard, M. Tuhaime, P. S. Thiry, and G. Drouin, Use of gait simulation in the evaluation of a spring-loaded knee joint orthosis for Duchenne muscular dystrophy patients, Medical & Biological Engineering & Computing, vol.Sept., issue.2, pp.165-170, 1981.
DOI : 10.1007/BF02442710

P. D. Vita, M. Torry, K. L. Glover, and D. L. Sperroni, A functional knee brace alters joint torque and power patterns during walking and running, Journal of Biomechanics, vol.29, issue.5, pp.583-588, 1996.
DOI : 10.1016/0021-9290(95)00115-8

I. Guigues and D. Staps, Biomechanical Evaluation of a Device for Assistance in Knee Flexion, 1998.

R. Mcn and . Alexander, Three Uses for Springs in Legged Locomotion, The Int. J. of Robotics Research, vol.9, issue.2, pp.53-61, 1990.

G. T. Yamaguchi and A. Takanishi, Development of a biped walking robot having antagonistic driven joints using nonlinear spring mechanism, Proceedings of International Conference on Robotics and Automation, pp.185-192, 1997.
DOI : 10.1109/ROBOT.1997.620036

R. Q. Van-der-linde, Active leg compliance for passive walking, Proceedings. 1998 IEEE International Conference on Robotics and Automation (Cat. No.98CH36146), 1998.
DOI : 10.1109/ROBOT.1998.680673

M. Bergerman, C. Lee, and Y. Xu, Experimental study of an underactuated manipulator, Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots, pp.317-322, 1995.
DOI : 10.1109/IROS.1995.526235

M. Bergerman, C. Lee, and Y. Xu, A dynamic coupling index for underactuated manipulators, Journal of Robotic Systems, vol.113, issue.4, pp.693-707, 1995.
DOI : 10.1002/rob.4620121006

URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.30.6455

S. Mochon and T. A. Mcmahon, Ballistic walking: an improved model, Mathematical Biosciences, vol.52, issue.3-4, pp.241-260, 1980.
DOI : 10.1016/0025-5564(80)90070-X

M. C. Laiou and A. Astolfi, Underactuated Nonlinear Systems with Non-stabilizable Linear Approximation: A Case Study, IFAC Int. Workshop on Motion Control, pp.23-238, 1998.

A. De-luca, R. Mattone, and G. Oriolo, Control of underactuated mechanical systems: application to the planar 2R robot, Proceedings of 35th IEEE Conference on Decision and Control, pp.1455-1460, 1996.
DOI : 10.1109/CDC.1996.572718

M. Reyhanoglu, A. Van-der-shaft, N. H. Mcclamroch, and I. Kolmanovsky, Nonlinear control of a class of underactuated systems, Proceedings of 35th IEEE Conference on Decision and Control, pp.1682-1687, 1996.
DOI : 10.1109/CDC.1996.572793

G. Oriolo and Y. Nakamura, Control of mechanical systems with second-order nonholonomic constraints: underactuated manipulators, [1991] Proceedings of the 30th IEEE Conference on Decision and Control, pp.2398-2403, 1991.
DOI : 10.1109/CDC.1991.261620

G. A. Pratt and M. M. Williamson, Series elastic actuators, Proceedings 1995 IEEE/RSJ International Conference on Intelligent Robots and Systems. Human Robot Interaction and Cooperative Robots, pp.399-406, 1995.
DOI : 10.1109/IROS.1995.525827

URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.380.8194

J. Pratt, P. Dilworth, and G. Pratt, Virtual model control of a bipedal walking robot, Proceedings of International Conference on Robotics and Automation, 1997.
DOI : 10.1109/ROBOT.1997.620037

M. Spong, Swing Up Control of the Acrobot Using Partial Feedback Linearization, Prep. IFAC Symposium on Robot Control, pp.833-838, 1994.

M. D. Berkemeier and R. S. Fearing, Sliding and hopping gaits for the underactuated Acrobot, IEEE Transactions on Robotics and Automation, vol.14, issue.4, pp.629-634, 1998.
DOI : 10.1109/70.704235

F. Saito, T. Fukuda, and F. Arai, Swing and locomotion control for two-link brachiation robot, [1993] Proceedings IEEE International Conference on Robotics and Automation, pp.5-12, 1994.
DOI : 10.1109/ROBOT.1993.291874

J. J. Borrelly, The ORCCAD Architecture, The International Journal of Robotics Research, vol.17, issue.4, pp.338-359, 1998.
DOI : 10.1177/027836499801700403

URL : https://hal.archives-ouvertes.fr/hal-00930119

A. Goswami, B. Espiau, and A. Keramane, Limit Cycles in a Passive Bipedal Gait and Passivity-mimicking Control Laws, Autonomous Robots, vol.4, issue.3, pp.273-286, 1997.
DOI : 10.1023/A:1008844026298

B. Espiau and R. Boulic, On the Computation and Control of the Mass Center of Articulated Chains, www.inria.fr/RRRT/publications-eng.html), submitted to Multibody System Dynamics
URL : https://hal.archives-ouvertes.fr/inria-00073210

F. Génot and B. Espiau, On the Control of the Mass Center of Legged Robots Under Unilateral Constraints, CLAWAR Symposium, 1998.