Modelling the effect of ‘heel to toe’ roll-over contact on the walking dynamics of passive biped robots

Mahmoodi, P.; Ransing, R. S.; Friswell, Michael I.

doi:10.1016/j.apm.2013.02.048

Cited by 19 publications

(19 citation statements)

References 36 publications

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“…Research into the simple point foot model is still being used today, not only as a simple approach to the biomechanics of walking but also for in-depth analysis of the inverted double pendulum dynamics (Chyou et al, 2011;Garcia et al, 1998;Goswami, Thuilot, & Espiau, 1996;Li & Yang, 2012). Other walkers are commonly modelled with flat (Goswami, 1999) or curved/circular feet; however it has been shown that foot kinematics has a direct influence on the stability of a bipedal robot (Mahmoodi, Ransing, & Friswell, 2013). This rolling contact may be modelled using an effective rocker to describe the function of the knee-ankle-foot complex in human walking as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 98%

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Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Charles

Mahmoodi

Ransing

et al. 2016

European Journal of Computational Mechanics

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Traditional biped walkers based on passive dynamic walking usually have flat or circular feet. This foot contact may be modelled with an effective rocker -represented as a roll-over shape -to describe the function of the knee-ankle-foot complex in human ambulation. Mahmoodi et al. has represented this rollover shape as a polygon with a discretised set of collisions. In this paper point foot, collisional and smooth rolling contact models are compared. An approach based on the Lagrangian mechanics is used to formulate the equations for the swing phase that conserves mechanical energy. Qualitative insight can be gained by studying the bifurcation diagrams of gait descriptors such as average velocity, step period, mechanical energy and interleg angle for different gain and length values for the feet, as well as different mass and length ratios. The results from the three approaches are compared and discussed. In the case of a rolling disk, the collisional contact model gives a negligible energy loss; incorporated into the double inverted pendulum system, however, reveals much greater errors. This research is not only useful for understanding the stability of bipedal walking, but also for the design of rehabilitative devices such as prosthetic feet and orthoses. ARTICLE HISTORY

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Section: Introductionmentioning

confidence: 98%

“…The collisional rolling model described byMahmoodi, Ransing, and Friswell (2013). The roll-over shape outlined in Equation 1 is discretised into a concave polygon to emulate the rolling contact.…”

mentioning

confidence: 99%

Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Charles

Mahmoodi

Ransing

et al. 2016

European Journal of Computational Mechanics

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“…As discussed in Section 2.1.6, the human neuro-musculoskeletal system conforms to rolling contact while walking. Most passive dynamic walkers use point feet as a simplification to the walking dynamics, however the shape of the foot has been shown to have a direct effect on the gait behaviours [89]. A passive biped may have flat feet [63,146] or arc feet [58] and comparisons between them have been published [77,61], showing that curved feet can increase the stable walking range and basin of attraction with flat-feet also providing an advantage over point foot by less collisional losses.…”

Section: Other Extensions To the Compass Walking Modelmentioning

confidence: 99%

“…The coordinates of the foot contact is represented as a function of the leg angle x θ (θ 1 ), y θ (θ 1 ) (derived from roller radius in Appendix 3.1.1) which allows for flexibility for the shape of the foot. The foot shape may be represented as a polynomial function with a defined heel length and forefoot length [89,12], however in this section, the radius of curvature of the foot is taken as 30% of the leg length [94,45] Periodic solutions exist for the state of q(t) = (θ(t),θ(t)). These orbits in space state are known as limit cycles, which correspond to the Poincaré return map.…”

Section: Values Used For Parametersmentioning

confidence: 99%

“…As discussed in Section 2.1.6, the contact created by the human lower leg system conforms to a rocker that has a radius of approximately one third the leg length [94,45,2]. The model outlined in this chapter has the capability of using a polynomial function for the foot contact [89,12], however the results in this section use a model with no defined foot length and radius of curvature, results show that this may be due to the inability of some prosthetic feet to match an appropriate roll-over shape. There is an almost symmetrical relationship between the difference in rocker radii on most of the gait characteristics, whether it increases or decreases; the asymmetric nature is more apparent rather than the average effect on gait parameters.…”

Section: Asymmetric Roller Radius Rmentioning

confidence: 99%

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Dynamic Walking Models to Understand Asymmetric Gait Characteristics

Charles¹

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Passive dynamic walking models remarkably predict gait behaviour such as walk-run transition speeds, preferred step length, stride frequencies and-with the inclusion of springs-ground reaction forces. Muscular or neurological conditions may lead to asymmetric walking characteristics that, in turn, come with long term health risks. Gait analysis may be used to understand an individual patient's conditions to help rehabilitate them. However, people adapt their kinematic and kinetic walking patterns so it can be hard to distinguish the effects of gait alterations such as inertial imbalance or injury. In this thesis a compass walking model with no active controllers is explored to understand the dynamics of gait. To help us interpret the effects of mass imbalance with a prosthetic foot or orthotic device, asymmetric loading conditions are investigated. A simple spring-mass walking model is used to explore the effects of altered touchdown angles and effective leg stiffness to see if these are used as strategies to alter the characteristics of gait. Results show that an asymmetric touchdown angle alters step length while retaining a symmetric stance time. A hybrid model is then derived with springs to emulate human-like ground reaction forces and asymmetric inertial loading of the legs. Results support previous research that pushoff from the trailing leg propels the leg mass more than the body mass. Higher rates of joint forces, larger step lengths and a longer stance time on the residual limb may be due to the prosthetic leg stiffness or the higher location of centre-of-mass. These results help us understand how the dynamic components affect gait characteristics such as step length, stance time and walking speeds. This work is motivated by the needs of persons with disabilities and by the desire to understand human walking.

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Realization Method of Stable Continuous Steering Jumping for a Bioinspired Jerboa Robot

Zhang,

Wang,

et al. 2023

Advcd Theory and Sims

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The continuous jumping of bioinspired robots in 3D spaces can greatly improve its motion flexibility, which is one of the highlights of research on jumping robots. However, most existing jumping robots can only move in a plane, and achieving stable continuous steering jumping is difficult. In this study, a realization method of stable continuous steering jumping for a bioinspired jerboa robot is proposed. On the basis of the jumping mechanism of the jerboa, the robot mechanism model is established, and the factors affecting motion feasibility and performance are analyzed in detail. Then, mathematical models of the stability indices of the robot jumping on uneven ground with redundant driving are established. Based on the proposed improved bee colony algorithm, the motion parameters and driving parameters can be determined. Simulation results show that the robot can realize stable continuous steering jumping in different terrains along the expected trajectory, thus proving the feasibility of the method proposed in this study. This study provides a theoretical reference for the high‐speed flexible motion of legged robots in 3D spaces.

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Modelling the effect of ‘heel to toe’ roll-over contact on the walking dynamics of passive biped robots

Cited by 19 publications

References 36 publications

Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Dynamic Walking Models to Understand Asymmetric Gait Characteristics

Realization Method of Stable Continuous Steering Jumping for a Bioinspired Jerboa Robot

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