This paper presents the experimental validation of a framework for the systematic design, analysis, and performance enhancement of controllers that induce stable walking in Nlink underactuated planar biped robots. Controllers designed via this framework act by enforcing virtual constraintsholonomic constraints imposed via feedback-on the robot's configuration which create an attracting two-dimensional invariant set in the full walking model's state space. Stability properties of resulting walking motions are easily analyzed in terms of a two-dimensional sub-dynamic of the full walking model. A practical introduction to and interpretation of the framework is given. In addition, the paper develops the ability to regulate the average walking rate of the biped to a continuum of values by modification of within-stride and stride-boundary characteristics, such as step length.

The adaptive regulation is an important issue with a lot of potential for applications in active suspension, active vibration control, disc drives control and active noise control. One of the basic problems from the "control system" point of view is the rejection of multiple unknown and time varying narrow band disturbances without using an additional transducer for getting information upon the disturbances. An adaptive feedback approach has to be considered for this problem. Industry needs a state of the art in the field based on a solid experimental verification. The paper presents a benchmark problem for suppression of multiple unknown and/or timevarying vibrations and an associated active vibration control system using an inertial actuator on which the experimental verifications have been done. The benchmark has three levels of difficulty and the associated control performance specifications are presented 1. An extensive comparison of the results obtained by various approaches will be presented 2. * Control system department of GIPSA-LAB, St. Martin d'héres, 38402 FRANCE (e-mail: [ioan-dore.landau, tudor-bogdan.airimitoaie, abraham.castellanos-silva, Gabriel.Buche]@gipsa-lab.grenoble-inp.fr). † Paulstra S.A.; Vibrachoc Division 1 The GIPSA-LAB team has done the experiments for all the contributors. 2 Results for some of the approaches are included in the proceedings of ECC 13[3], [8], [9], [7], [1], [18].

International audienceAn active vibration control system using an inertial actuator for suppression of multiple unknown and/or time-varying vibrations will be presented. The objective is to minimize the residual force by applying an appropriate control effort through the inertial actuator. The system does not use any additional transducer for getting in real-time information upon the disturbances. A direct feedback adaptive regulation scheme for the suppression of multiple unknown and/or time-varying vibrations will be used and evaluated in real time. It uses the internal model principle and the Youla-Kucera parametrization. In the Appendix, a comparison with an alternative indirect adaptive regulation scheme is presented

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Summary. This paper reviews and expands the class of hybrid zero dynamics (HZD) controllers that induce stable running in bipedal robots and discusses related experiments conducted in September 2004 in Grenoble, France. In these experiments, RABBIT, a five-link, four-actuator, planar bipedal robot, executed six consecutive running steps. These steps were notably human-like, having a long stride length (approx. 50 cm or 36% of body length), flight phases of significant duration (approx. 100 ms or 25% of the step duration), an upright posture, and an average forward rate of 0.6 m/s. A video is available at [8,18]. Validation of the theory's prediction that the running gait would be stable was not possible in the time available for the experiments. Unmodeled dynamic and geometric effects that contributed to the implementation difficulties are discussed.