Self-stability of a simple walking model driven by a rhythmic signal

Aoi, Shinya; Tsuchiya, Kazuo

doi:10.1007/s11071-006-9030-3

Cited by 36 publications

(28 citation statements)

References 51 publications

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“…For example, a movement generated by a 'predetermined pattern' acting as input to a musculo-skeletal system under gravity (Ringrose, 1997b;Aoi and Tsuchiya, 2007) might be as self-stable as spring-mass walking or running Ghigliazza et al, 2005;Owaki and Ishiguro, 2007). Other examples of self-stable mechanisms are: a purely passive robot steadily moving down a slope under gravity plus roll friction (McGeer, 1990a;McGeer, 1990b), insect locomotion in the horizontal plane (Schmitt and Holmes, 2000a;Schmitt and Holmes, 2000b;Schmitt and Holmes, 2001), oscillations induced by a fixed muscle stimulation program (Wagner and Blickhan, 1999;Wagner and Blickhan, 2003), robot juggling (Schaal et al, 1996), and somersault locomotion (Mombaur et al, 2005).…”

Section: Self-stabilitymentioning

confidence: 99%

Running on uneven ground: leg adjustment to vertical steps and self-stability

Grimmer

Ernst

Günther

et al. 2008

Journal of Experimental Biology

114

133

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SUMMARYHuman running is characterized by comparably simple whole-body dynamics. These dynamics can be modelled with a point mass bouncing on a spring leg. Theoretical studies using such spring-mass models predict that running can be self-stable. In simulations, this self-stability allows for running on uneven ground without paying attention to the ground irregularities. Whether humans actually use this property of the mechanical system in such an irregular environment is, however, unclear. One way to approach this question is to study how the leg stiffness in stance and the leg orientation in flight are changed in response to ground perturbations. Here, for 11 human subjects we studied two consecutive contacts during running on uneven ground with a force plate of adjustable height (step of +5, +10 and +15 cm). We found that runners adjust their leg stiffness to the height of a vertical step. The adjustment is characterized by a 9% increase in leg stiffness in preparation for the perturbation and by a systematic decrease in proportion to the step height. At the highest vertical step (+15 cm), leg stiffness was reduced by about 26%. We also observed that the angle of attack decreased from 68 deg. to 62 deg. with increasing ground height. These leg adjustments are in accordance with the predictions of a stable spring-mass system. Furthermore, we could describe the identified leg forces and leg compressions with a simple spring-mass simulation for a given body mass, leg stiffness, angle of attack and initial conditions. We compared the experimental findings with the self-stabilizing properties of the spring-mass model, and discuss how humans use a combination of strategies that include purely mechanical self-stabilization and active neuromuscular control. Finally, beyond self-stability, we suggest that control may apply to smooth centre of mass kinematics.

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Section: Self-stabilitymentioning

confidence: 99%

Running on uneven ground: leg adjustment to vertical steps and self-stability

Grimmer

Ernst

Günther

et al. 2008

Journal of Experimental Biology

114

133

View full text Add to dashboard Cite

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“…stability and controllability of walking dynamics) is different in these two approaches. From this perspective, it is particularly interesting to conduct a compara- The lower plots show the frequency parameter of oscillator, and the stride length of every step during the three successful trials tive study between the proposed controller and the other approaches such as the phase resetting controllers, the reflexbased controllers and the CPG-based controllers (Aoi and Tsuchiya 2007;Taga et al 1991;Manoonpong et al 2007;Ijspeert 2008).…”

Section: Resultsmentioning

confidence: 99%

Minimalistic control of biped walking in rough terrain

Iida

Tedrake

2010

Auton Robot

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Toward our comprehensive understanding of legged locomotion in animals and machines, the compass gait model has been intensively studied for a systematic investigation of complex biped locomotion dynamics. While most of the previous studies focused only on the locomotion on flat surfaces, in this article, we tackle with the problem of bipedal locomotion in rough terrains by using a minimalistic control architecture for the compass gait walking model. This controller utilizes an open-loop sinusoidal oscillation of hip motor, which induces basic walking stability without sensory feedback. A set of simulation analyses show that the underlying mechanism lies in the "phase locking" mechanism that compensates phase delays between mechanical dynamics and the open-loop motor oscillation resulting in a relatively large basin of attraction in dynamic bipedal walking. By exploiting this mechanism, we also explain how the basin of attraction can be controlled by manipulating the parameters of oscillator not only on a flat terrain but also in various inclined slopes. Based on the simulation analysis, the proposed controller is implemented in a real-world robotic platform to confirm the plausibility of the approach. In addition, by using these basic principles of self-stability and gait variability, we demonstrate how the proposed controller can be extended with a simple sensory feedback such that the robot is able to control gait patterns autonomously for traversing a rough terrain.

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“…A few potential research directions in the future include the extension of physical model with knee and ankle joints as previously shown in [10], [12], [19], and the enhancement of the control architecture with more dynamic features [13], [18], [20], [21].…”

Section: Discussionmentioning

confidence: 99%

“…And third, due to its simplicity, the model can be easily extended to its variations for a systematic analysis. iida@csail.mit.edu, russt@mit.edu Previously this simple model showed limit cycles of passive dynamic walking in slopes [9], and the model was enhanced with various motor control to deal with a flat terrain [10], [11], [12], [13] and with the other variations of environment [14], [15], [16], [17], [18]. The investigations of this model, however, were mainly conducted in simulation with a few exceptions [10], [12], and the model has not been tested in the real-world rough terrains previously.…”

Section: Introductionmentioning

confidence: 99%

Minimalistic control of a compass gait robot in rough terrain

Iida

Tedrake

2009

2009 IEEE International Conference on Robotics and Automation

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Abstract-Although there has been an increasing interest in dynamic bipedal locomotion for significant improvement of energy efficiency and dexterity of mobile robots in the real world, their locomotion capabilities are still mostly restricted on flat surfaces. The difficulty of dynamic locomotion in rough terrain is mainly originated in the stability and controllability of gait patterns while exploiting the natural mechanical dynamics of the robots. For a systematic investigation of the challenging problem, this paper presents the simplest control architecture for the compass gait model which can be used for locomotion in rough terrain. Locomotion of the model is mainly achieved by an open-loop oscillator which induces self-stabilizing gait patterns, and we test the proposed control architecture in a real-world robotic platform. In addition, we also found that this controller is capable of varying stride length with a minimum change of control parameters, which enables locomotion in rough terrains. By using these basic principles of self-stability and gait variability, we extended the proposed controller with a simple sensory feedback about the location in the environment, which makes the robot possible to control gait patterns autonomously for traversing a rough terrain. We describe a set of experimental results and discuss how the proposed minimalistic control architecture can be enhanced for dynamic locomotion control in more complex environment.

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Self-stability of a simple walking model driven by a rhythmic signal

Cited by 36 publications

References 51 publications

Running on uneven ground: leg adjustment to vertical steps and self-stability

Running on uneven ground: leg adjustment to vertical steps and self-stability

Minimalistic control of biped walking in rough terrain

Minimalistic control of a compass gait robot in rough terrain

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