Dynamically Stable Legged Locomotion

Raibert, Marc H.; Brown, H.B.; Chepponis, Michael; Koechling, Jeff; Hodgins, Jessica K.

doi:10.21236/ada120692

Cited by 43 publications

(10 citation statements)

References 170 publications

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“…It is hypothesized that SLR enhances performance of biological systems 5 , and that we might use SLR to improve the performance of legged robots, such as the Phides robot shown in Figure 1. Use of SLR to improve controller performance is attractive, because it is a conceptually simple extension to any foot placement controller, such as the constant angle of attack controller 6 and the neutral point controller 7 . The effect of swing-leg retraction on limit cycle walking 8 is relatively well studied and has been shown to improve energy efficiency, small disturbance stability, and large disturbance rejection [9][10][11] .…”

Section: Introductionmentioning

confidence: 99%

The effects of swing-leg retraction on running performance: analysis, simulation, and experiment

et al. 2014

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Using simple running models, researchers have argued that swing-leg retraction can improve running robot performance. In this paper, we investigate whether this holds for a more realistic simulation model validated against a physical running robot. We find that swing-leg retraction can improve stability and disturbance rejection. Alternatively, swing-leg retraction can simultaneously reduce touchdown forces, slipping likelihood, and impact energy losses. Surprisingly, swing-leg retraction barely affected net energetic efficiency. The retraction rates at which these effects are greatest are strongly model dependent, suggesting that robot designers cannot always rely on simplified models to accurately predict such complex behaviors.

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Section: Introductionmentioning

confidence: 99%

The effects of swing-leg retraction on running performance: analysis, simulation, and experiment

et al. 2014

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“…2.2. The notion of virtual legs has been used with great success by Raibert to control his two-and four-legged robots by extending the one-leg control algorithms, [60], [63]. It allows several separate physical legs to be represented by fewer virtual legs, Fig.…”

Section: Running Gaits and Locomotion Modelsmentioning

confidence: 99%

On the stable passive dynamics of quadrupedal running

Poulakakis

Papadopoulos

Buehler

2003 IEEE International Conference on Robotics and Automation (Cat. No.03CH37422)

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In this thesis, the dynamics of quadrupedal running via the bounding gait is studied. To analyse the properties of the passive dynamics of Scout II, a model consisting of a body and two massless spring-loaded prismatic legs is introduced.A return map is derived to study the existence of periodic system motions.Numerical studies of the return map show that passive generation of cyclic motion is possible. Most strikingly, local stability analysis of the return map shows that the dynamics of the open loop passive system alone can confer stability of the motion. Stability improves at higher speeds, a fact which is in agreement with recent results from Biomechanics showing that the dynamics of the body become dominant in determining stability when animals run at high speeds. Furthermore, pronking is found to be more unstable than bounding, which explains why Scout II shows a "preference" for the bounding gait. These results can be used in developing a general control methodology for legged robots, resulting from the synthesis of feed-forward and feedback models that take advantage of the mechanical system.ii RésuméCette thèse examine la dynamique d'un système quadrupède qui posséde une démarche de bondissement. Pour analyser les propriétés de la dynamique passive de Scout II un modèle se composant d'un corps et de deux jambes prismatiques à ressort sans masse est présenté. Une carte de retour est dérivée pour étudier l'existence des mouvements périodiques du système. Les études numériques de la carte de retour prouvent que la génération passive du mouvement cyclique est possible. L'analyse locale de stabilité de la carte de retour prouve que seul la dynamique du système passif sans rétroaction peut conférer stabilité du mouvement. La stabilité s'améliore à des vitesses plus élevées, un fait qui est en accord avec des résultats récents Biomécanique que la dynamique du corps devient dominante dans la détermination de la stabilité quand les animaux fonctionnent aux vitesses élevées. En outre, pronking s'avère plus instable que le bondissement, qui explique pourquoi Scout II montre une préférence pour la démarche de bondissement. Ces résultats et la synthèse des modèles alimenter vers l'avant et de rétroaction peuvent être employés en développant une méthodologie générale de commande pour les robots ambulatoire.iii

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“…Schiehlen [55] developed a bipedal locomotion system with StarlETH [28] proposed a 23 kg compliant quadrupedal robot, with a trotting gait walking at the speed of 0.43 m/s, when electric power equals 360 W. The robot was designed as a device with an adaptive torque control mechanism. Raibert's quadrupedal robot [48] was as heavy as 32 kg, and had multiple modes of running gaits-based legs moving in pairs: the trot, pace and bound locomotion. Scout II [63] was a 24 kg autonomous four-legged robot with only one actuator per compliant leg.…”

Section: Specific Resistancementioning

confidence: 99%

Energy-efficacy comparisons and multibody dynamics analyses of legged robots with different closed-loop mechanisms

Komoda

Wagatsuma

2016

Multibody Syst Dyn

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As for biological mechanisms, which provide a specific functional behavior, the kinematic synthesis is not so simply applicable without deep considerations on requirements, such as the ideal trajectory, fine force control along the trajectory, and possible minimization of the energy consumption. An important approach is the comparison of acknowledged mechanisms to mimic the function of interest in a simplified manner. It helps to consider why the motion trajectory is generated as an optimum, arising from a hidden biological principle on adaptive capability for environmental changes. This study investigated with systematic methods of forward and inverse kinematics known as multibody dynamics (MBD) before going to the kinematic synthesis to explore what the ideal end-effector coordinates are. In terms of walking mechanisms, there are well-known mechanisms, yet the efficacy is still unclear. The Chebyshev linkage with four links is the famous closed-loop system to mimic a simple locomotion, from the 19th century, and recently the Theo Jansen mechanism bearing 11 linkages was highlighted since it exhibited a smooth and less-energy locomotive behavior during walking demonstrations in the sand field driven by wind power. Coincidentally, Klann (1994) emphasized his closed-loop linkage with seven links to mimic a spider locomotion. We applied MBD to three walking linkages in order to compare factors arising from individual mechanisms. The MBD-based numerical computation demonstrated that the Chebyshev, Klann, and Theo Jansen mechanisms have a common property in acceleration control during separate swing and stance phases to exhibit the walking behavior, while they have different tendencies in the total energy consumption and energy-efficacy measured by the 'specific resistance'. As a consequence, this study for the first time revealed that specific resistances of three linkages exhibit a proportional relationship to the walking speed, which is consistent with human walking and running, yet interestingly it is not consistent with older walking machines, like ARL monopod I, II. The results imply a similarity between biological evolution and robot design, in that the Chebyshev mechanism provides the simplest walking motion with fewer linkages and the Theo Jansen mechanism realizes a fine profile of force changes along the trajectory to reduce the energy consumption acceptable for a large body size by increasing the number of links.

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Dynamically Stable Legged Locomotion

Cited by 43 publications

References 170 publications

The effects of swing-leg retraction on running performance: analysis, simulation, and experiment

The effects of swing-leg retraction on running performance: analysis, simulation, and experiment

On the stable passive dynamics of quadrupedal running

Energy-efficacy comparisons and multibody dynamics analyses of legged robots with different closed-loop mechanisms

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