Dynamic considerations of heel-strike impact in human gait

Ros, Javier; Font-Llagunes, Josep M.; Plaza, Aitor; Kövecses, József

doi:10.1007/s11044-015-9460-0

Cited by 7 publications

(4 citation statements)

References 29 publications

(43 reference statements)

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“…This means that models for inverse dynamics simulations [7]- [9] are not useful in this context, since they can only predict forces from experimental motion. Also, although impulsive models [10], [11] yield practically the same motion as continuous contact models, they provide little information on contact forces, which is less useful for certain studies. A continuous contact model can be used in a forward dynamic simulation and calculates the contact forces throughout impact and contact.…”

Section: Introductionmentioning

confidence: 99%

A 3D ellipsoidal volumetric foot–ground contact model for forward dynamics

Brown

McPhee

2017

Multibody Syst Dyn

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Foot-ground contact models are an important part of forward dynamic biomechanic models, particularly those used to model gait, and have many challenges associated with them. Contact models can dramatically increase the complexity of the multibody system equations, especially if the contact surface is relatively large or conforming. Since foot-ground contact has a large potential contact area, creating a computationally efficient model is challenging. This is particularly problematic in predictive simulations, which may determine optimal performance by running a model simulation thousands of times. An ideal contact model must find a balance between accuracy for large, conforming surfaces, and computational efficiency.Volumetric contact modelling is explored as a computationally efficient model for footground contact. Previous foot models have used volumetric contact before, but were limited to 2D motion and approximated the surfaces as spheres or 2D shapes. The model presented here improves on current work by using ellipsoid contact geometry and considering 3D motion and geometry. A gait experiment was used to parametrise and validate the model. The model ran over 100 times faster than real-time (in an inverse simulation at 128 fps) and matched experimental normal force and centre of pressure location with less than 7% root-mean-square error.In most gait studies, only the net reaction forces, centre of pressure, and body motions are recorded and used to identify parameters. In this study, contact pressure was also recorded and used as a part of the identification, which was found to increase parameter optimisation time from 10 s to 164 s (due to the additional time needed to calculate the pressure distribution) but helped the results converge to a more realistic model. The model matched experimental pressures with 33-45% root-mean-square error, though some of this was due to measurement errors.The same parametrisation was done with friction included in the foot model. It was determined that the velocity-based friction model that was used was inappropriate for use in an inverse-dynamics simulation. Attempting to optimise the model to match experimental friction resulted in a poor match for friction forces, inaccurate values for the coefficient of friction, and a poorer match to the experimental normal force.

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Section: Introductionmentioning

confidence: 99%

A 3D ellipsoidal volumetric foot–ground contact model for forward dynamics

Brown

McPhee

2017

Multibody Syst Dyn

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“…Therefore, it must be wasted (converted to heat) [21] stretching the stance leg. In human walking, such stretch might also cancel a significant por on of mechanical energy stored in ligaments and tendons during the heel strike which is usually released in the subsequent push-off [22][23][24]. The higher than muscle ac ve work performance walking efficiencies observed during walking indicates the share of elas city in walking [20,25].…”

Section: Discussionmentioning

confidence: 99%

Optimum Push-off During Uneven Walking for Just-in-Time Strategy; Delayed Push-off Exertion is Mechanically Costly

Hosseini-Yazdi

2024

Preprint

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It is shown that step mechanical work roughly describes walking energetics, and optimal walking economy is achieved by pre-emptive step work. We suggest this is also true for uneven walking. Using a simple powered walking model, we estimated the preferred pre-emptive push-offs to cover the entire step energy. The maximum push-off is exerted when the subsequent heel-strike dissipation is zero, setting an upper bound for step-up amplitude achievable with pre-emptive push-off. For instance, at a walking speed of 1.4 m · s−1, the maximum step-up is 0.106 m. Conversely, for any step-up amplitude, there is a minimum walking speed. For a step-up height (Δh) of 0.06 m, the minimum walking speed is 1.06 m · s−1. The importance of pre-emptive push-off and optimal timing of push-off and collision is widely discussed. However, there are cases where this timing is undermined, such as during uneven walking, necessitating post-transition mechanical energy compensation. The ankle (via delayed push-off) or hip can provide mid-flight energy, but no mechanical determinant prefers one source over the other. Our modeling demonstrates that delayed push-off entails mechanical energy waste, likely converted to heat by stretching the stance leg. This stretch may also release energy stored during the heel-strike (e.g., in the Achilles tendon), exacerbating the required mechanical work performance in the subsequent step transition. Hence, we propose that during the double support phase, when the stance leg is switched, hip actuation becomes mechanically preferable. Physiological observations also support our proposition.

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“…Furthermore, it is clear that the point of application of these contact forces varies with time during the interaction between the foot and the ground along stance period. This issue is of paramount importance in order to obtain proper results, as it was demonstrated in [60][61][62]. Thus, in order to correctly define the point of application of reaction forces in the system, it is necessary to calculate the local coordinates of this point in relation to the center-of-mass of the foot [30].…”

Section: Model Developmetmentioning

confidence: 99%

Influence of the Hip Joint Modeling Approaches on the Kinematics of Human Gait

Costa

Peixoto

Moreira

et al. 2016

Journal of Tribology

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The influence of the hip joint formulation on the kinematic response of the model of human gait is investigated throughout this work. To accomplish this goal, the fundamental issues of the modeling process of a planar hip joint under the framework of multibody systems are revisited. In particular, the formulations for the ideal, dry, and lubricated revolute joints are described and utilized for the interaction of femur head inside acetabulum or the hip bone. In this process, the main kinematic and dynamic aspects of hip joints are analyzed. In a simple manner, the forces that are generated during human gait, for both dry and lubricated hip joint models, are computed in terms of the system's state variables and subsequently introduced into the dynamics equations of motion of the multibody system as external generalized forces. Moreover, a human multibody model is considered, which incorporates the different approaches for the hip articulation, namely, ideal joint, dry, and lubricated models. Finally, several computational simulations based on different approaches are performed, and the main results are presented and compared to identify differences among the methodologies and procedures adopted in this work. The input conditions to the models correspond to the experimental data capture from an adult male during normal gait. In general, the obtained results in terms of positions do not differ significantly when different hip joint models are considered. In sharp contrast, the velocity and acceleration plotted vary significantly. The effect of the hip joint modeling approach is clearly measurable and visible in terms of peaks and oscillations of the velocities and accelerations. In general, with the dry hip model, intrajoint force peaks can be observed, which can be associated with the multiple impacts between the femur head and the cup. In turn, when the lubricant is present, the system's response tends to be smoother due to the damping effects of the synovial fluid.

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Dynamic considerations of heel-strike impact in human gait

Cited by 7 publications

References 29 publications

A 3D ellipsoidal volumetric foot–ground contact model for forward dynamics

A 3D ellipsoidal volumetric foot–ground contact model for forward dynamics

Optimum Push-off During Uneven Walking for Just-in-Time Strategy; Delayed Push-off Exertion is Mechanically Costly

Influence of the Hip Joint Modeling Approaches on the Kinematics of Human Gait

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