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...stability. In more complex models, combinations of continuous dynamics within stance and touchdown/liftoff switching or impact maps are involved, resulting in higher-dimensional Poincaré maps (e.g., =-=[237, 239, 238, 240, 138, 82, 249]-=- and see section 5), but while coupled equations of motion must be integrated through stance to derive these maps, the stability properties of their fixed points are still partly determined by trading...

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... a better understanding of the dynamics of biped locomotion we find it instructive to first explore the behavior of a simple walker model. Physical models[26][4] and theoretical and simulation results=-=[9]-=-[11] have demonstrated the fact that even passive biped robots with simple kinematics can successfully walk down an inclined slope in a steady gait. The motive power of such robots comes from the conv...

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...tions from the SLIP predictions, which can be quantified by a more detailed error analysis (see [10] and the references therein). In related work, McGeer [11] and, more recently, Ruina and colleagues =-=[12, 13]-=- have designed, analyzed, and built passive walking machines that are entirely uncontrolled yet produce stable gaits. These differ from SLIP-type machines in that their rigid legs incur impacts at tou...

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...ngth would be a good choice. However, we argue that a good local stability does not imply a good disturbance rejection for larger disturbances. As an example, we compare the findings of Garcia et al. =-=[2]-=- on the simplest walking model with our own. Their simplest walking model was equipped with point feet (foot radius equal to zero), and showed stable downhill walking for slopes up to 0.015 [rad]. How...

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...king corresponds to periodic motions of these dynamic systems. Such systems have been studied with no actuation and control (McGeer, 1990, 1991 [15, 16, 17]; McMahon, 1984 [18]; Garcia, et. al., 1997 =-=[6]-=-; Goswami,et. al., 1996 [7]) as well as with various amounts and types of power input and active control (see,e.g., Hemami and Chen, 1984 [11]; Furusho and Sano, 1990 [5]; Taga, 1991 [23]; Beletskii, ...

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...physiological accuracy of the models vary depending on the purpose of the study. Extremely simple models that are not physiologically realistic can and do give insight into biological function (e.g., =-=[14]-=-). On the other hand, more complex models that describe the physiology closely might be necessary to explain some other phenomenon of interest [15]. Most models used in understanding neuromuscular fun...

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... two-dimensional passive mechanical models that walk like humans. The models are two-dimensional because they can move only in the sagittal plane. More recently, Coleman and Ruina [22], Garcia et al. =-=[34]-=-, and Collins et al. [24] describe passive mechanical machines that walk in three dimensions. Collectively, these systems demonstrate that the jointed leg systems of humans have an innate ability to w...