Ground reaction forces intersect above the center of mass in single support, but not in double support of human walking

Vielemeyer, Johanna; Müller, Roy; Staufenberg, Nora-Sophie; Renjewski, Daniel; Abel, Rainer

doi:10.1016/j.jbiomech.2021.110387

Cited by 14 publications

(18 citation statements)

References 13 publications

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“…Analogous to the VPP model, an intersection point of the GRFs above the CoM could also be found in various experimental studies for human walking [5,[10][11][12][13][14], and even for some animals such as dogs [5,15], macaques [16] and quails [17]. In those experiments, the GRFs point to the VPP with a small spread.…”

Section: Introductionmentioning

confidence: 62%

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Walking like a robot: do the ground reaction forces still intersect near one point when humans imitate a humanoid robot?

et al. 2023

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Bipedal walking while keeping the upper body upright is a complex task. One strategy to cope with this task is to direct the ground reaction forces toward a point above the centre of mass of the whole body, called virtual pivot point (VPP). This behaviour could be observed in various experimental studies for human and animal walking, but not for the humanoid robot LOLA. The question arose whether humans still show a VPP when walking like LOLA. For this purpose, ten participants imitated LOLA in speed, posture, and mass distribution (LOLA-like walking). It could be found that humans do not differ from LOLA in spatio-temporal parameters for the LOLA-like walking, in contrast to upright walking with preferred speed. Eight of the participants show a VPP in all conditions ( R 2 > 0.90 ± 0.09), while two participants had no VPP for LOLA-like walking ( R 2 < 0.52). In the latter case, the horizontal ground reaction forces are not balanced around zero in the single support phase, which is presumably the key variable for the absence of the VPP.

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Section: Introductionmentioning

confidence: 62%

“…with at least one pair of i, j, so that u ij Exp = u Exp . The VPP as well as the R 2 were calculated for the exact single support phase, as described in Vielemeyer et al [13].…”

Section: ð2:1þmentioning

confidence: 99%

Walking like a robot: do the ground reaction forces still intersect near one point when humans imitate a humanoid robot?

et al. 2023

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“…However, the double support phase, with the feet planted on surfaces at different heights, is understudied, consistent with a relative neglect of this phase in the locomotion literature [ 21 ]. When both feet contact the ground, there are more kinetic degrees of freedom, which offers greater control authority over the gait cycle [ 14 , 22 ]. Therefore, this phase of gait, although brief (lasting 20% of the gait cycle), may be an opportunity for modulating the body’s motion for achieving specific kinematic goals to navigate hazards.…”

Section: Discussionmentioning

confidence: 99%

Locomotion control during curb descent: Bilateral ground reaction variables covary consistently during the double support phase regardless of future foot placement constraints

et al. 2022

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During community ambulation, anticipatory adaptations in gait are key for navigating built, populated and natural environments. It has been argued that some instability in gait can be functionally beneficial in situations demanding high maneuverability, and while the mechanisms utilized to maintain locomotor balance are well understood, relatively less is known about how the control of gait stability changes to facilitate upcoming maneuvers in challenging environments. The double support phase may be important in this regard; since both feet can push off the ground simultaneously, there is greater control authority over the body’s movement during this phase. Our goal was to identify how this control authority is exploited to prepare for upcoming maneuvers in challenging environments. We used synergy indices to quantify the degree of coordination between the ground reaction forces and moments under the two feet for stabilizing the resultant force and moment on the body during the double support phase of curb descent. In contrast to our expectations, we observed that the kinetic synergy indices during curb descent were minimally influenced by expected foot targeting maneuvers for the subsequent step. Only the resultant moment in the frontal plane showed reduced stability when targeting was required, but the synergy index was still high, indicating that the resultant moment was stable. Furthermore, the synergy indices indicated that the main function of the ground reaction variables is to maintain stability of whole-body rotations during double support, and this prerogative was minimally influenced by the subsequent foot targeting tasks, likely because the cost of losing balance while descending a curb would be higher than the cost of mis-stepping on a visual target. Our work demonstrates the salience of stabilizing body rotations during curb negotiation and improves our understanding of locomotor control in challenging environments.

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“…This model was based on the observations that the GRFs intersecting in one or more points above the CoM, resulting in a constellation similar to a physical pendulum [20]. This intersection point is observed in humans on treadmills (Note that the VP is only observed during the single support phase in humans [21]. However, the VPP model assumes that the GRFs are also redirected into the VPP during the double-support phase.)…”

Section: Basic Human Gait Modelsmentioning

confidence: 99%

Hardware-in-the-Loop Test of a Prosthetic Foot

et al. 2021

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For a targeted development process of foot prostheses, a profound understanding of the dynamic interaction between humans and prostheses is necessary. In engineering, an often employed method to investigate the dynamics of mechanical systems is Hardware-in-the-Loop (HiL). This study conducted a fundamental investigation of whether HiL could be an applicable method to study the dynamics of an amputee wearing a prosthesis. For this purpose, a suitable HiL setup is presented and the first-ever HiL test of a prosthetic foot performed. In this setup, the prosthetic foot was tested on the test bench and coupled in real-time to a cosimulation of the amputee. The amputee was modeled based on the Virtual Pivot Point (VPP) model, and one stride was performed. The Center of Mass (CoM) trajectory, the Ground Reaction Forces (GRFs), and the hip torque were qualitatively analyzed. The results revealed that the basic gait characteristics of the VPP model can be replicated in the HiL test. Still, there were several limitations in the presented HiL setup, such as the limited actuator performance. The results implied that HiL may be a suitable method for testing foot prostheses. Future work will therefore investigate whether changes in the gait pattern can be observed by using different foot prostheses in the HiL test.

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Ground reaction forces intersect above the center of mass in single support, but not in double support of human walking

Cited by 14 publications

References 13 publications

Walking like a robot: do the ground reaction forces still intersect near one point when humans imitate a humanoid robot?

Walking like a robot: do the ground reaction forces still intersect near one point when humans imitate a humanoid robot?

Locomotion control during curb descent: Bilateral ground reaction variables covary consistently during the double support phase regardless of future foot placement constraints

Hardware-in-the-Loop Test of a Prosthetic Foot

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