Running and Walking with Compliant Legs

Seyfarth, André; Geyer, Hartmut; Blickhan, Reinhard; Lipfert, Susanne W.; Rummel, Juergen; Minekawa, Yohei; Iida, Fumiya

doi:10.1007/978-3-540-36119-0_18

Cited by 39 publications

(27 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that subjects chose not self-stable combinations but rather combinations that would allow for immediate stability, knowing that other mechanisms for stable control would engage in later stages of locomotion. The retraction control scheme may be one such type of control mechanism Seyfarth et al, 2006).…”

Section: Stiffness and Angle Of Attack Adjustment Are Explained By A mentioning

confidence: 99%

“…Since its introduction it has been used in several research studies of hopping and running (e.g. Farley et al, 1991;Blickhan and Full, 1993;Full and Koditschek, 1999;Seyfarth et al, 2002;Geyer et al, 2006;Seyfarth et al, 2006) and in recent investigations of walking . The model consists of a mass-less spring and the body represented by a point mass and is simply described by the parameters stiffness k, angle of attack α 0 and leg length l 0 (Blickhan, 1989;McMahon and Cheng, 1990;Geyer, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…In simulations, by using leg retraction, changes in ground level of 50% of the initial leg spring length can be managed . Although swing-leg retraction is an important stabilizing mechanism, it has limitations at higher speeds and cannot increase stability by increasing the rotational velocity Seyfarth et al, 2006). Here, alternative strategies might be crucial for stable running.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Grimmer

Ernst

Günther

et al. 2008

Journal of Experimental Biology

112

133

View full text Add to dashboard Cite

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.

show abstract

Section: Stiffness and Angle Of Attack Adjustment Are Explained By A mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Grimmer

Ernst

Günther

et al. 2008

Journal of Experimental Biology

112

133

View full text Add to dashboard Cite

show abstract

“…Blickhan, 1989;Farley et al, 1993;Full and Koditschek, 1999;Geyer et al, 2006;McMahon and Cheng, 1990;Seipel and Holmes, 2007;Seyfarth et al, 2006;Seyfarth et al, 2002;Seyfarth et al, 2003). In this model, gravitational potential energy (E P ) and kinetic energy (E K ) are in phase and some energy is recovered through recoil in elastic structures (i.e.…”

Section: Introductionmentioning

confidence: 99%

Birds achieve high robustness in uneven terrain through active control of landing conditions

Birn-Jeffery

Daley

2012

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYWe understand little about how animals adjust locomotor behaviour to negotiate uneven terrain. The mechanical demands and constraints of such behaviours likely differ from uniform terrain locomotion. Here we investigated how common pheasants negotiate visible obstacles with heights from 10 to 50% of leg length. Our goal was to determine the neuro-mechanical strategies used to achieve robust stability, and address whether strategies vary with obstacle height. We found that control of landing conditions was crucial for minimising fluctuations in stance leg loading and work in uneven terrain. Variation in touchdown leg angle ( TD ) was correlated with the orientation of ground force during stance, and the angle between the leg and body velocity vector at touchdown ( TD ) was correlated with net limb work. Pheasants actively targeted obstacles to control body velocity and leg posture at touchdown to achieve nearly steady dynamics on the obstacle step. In the approach step to an obstacle, the birds produced net positive limb work to launch themselves upward. On the obstacle, body dynamics were similar to uniform terrain. Pheasants also increased swing leg retraction velocity during obstacle negotiation, which we suggest is an active strategy to minimise fluctuations in peak force and leg posture in uneven terrain. Thus, pheasants appear to achieve robustly stable locomotion through a combination of path planning using visual feedback and active adjustment of leg swing dynamics to control landing conditions. We suggest that strategies for robust stability are context specific, depending on the quality of sensory feedback available, especially visual input.

show abstract

“…This could also be addressed by including stance leg lengths and extension velocities in the state. Low level control or passive properties that make the legs appear to be compliant may allow the robot to achieve natural double support without explicit control [11]. We could also make these additional degrees of freedom functions of other aspects of the state, and thus not have to consider them during control law design [12].…”

Section: Discussionmentioning

confidence: 99%

Controlling Velocity In Bipedal Walking: A Dynamic Programming Approach

Mandersloot

Wisse

Atkeson

2006

2006 6th IEEE-RAS International Conference on Humanoid Robots

View full text Add to dashboard Cite

Abstract-We are interested in adding actuation to passive dynamic walkers to enable them to control their velocity. We control velocity by using dynamic programming to design control laws for each desired velocity. We consider three cases: a simulated planar compass gait walker, a simulated 3D compass gait walker with roll dynamics, and a simulated planar compass gait walker with a torso. Each of the walkers have massless legs. The actions include foot placement, ankle torque, and desired torso orientation. We use Poincaré sections to define the state of the model, and thus choose a new action once per footstep. The optimization criterion is based on the effort of swinging the limbs, applying torques, and maintaining the desired velocity. By generating control laws at different desired velocities and then selecting the appropriate control law we are able to control velocity in each of these walkers, and smoothly transition between different velocities. Our results also indicate how complex nonlinear control laws can be approximated by gain-scheduled linear control laws.

show abstract

Running and Walking with Compliant Legs

Cited by 39 publications

References 22 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

Birds achieve high robustness in uneven terrain through active control of landing conditions

Controlling Velocity In Bipedal Walking: A Dynamic Programming Approach

Contact Info

Product

Resources

About