Adding adaptable toe stiffness affects energetic efficiency and dynamic behaviors of bipedal walking

Sun, Shiqi; Huang, Yan; Wang, Qining

doi:10.1016/j.jtbi.2015.10.002

Cited by 12 publications

(10 citation statements)

References 36 publications

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“…This study also confirms Sun et al study, which states that a proper toe actuation mode reduces energy consumption of ankle joints. 16…”

Section: Benefits Of Passive Toe Jointmentioning

confidence: 99%

“…5,14 Also, Zhu et al and Sun et al indicated that adding proper passive toe joints could benefit the energy efficiency of ankle joint as well as the stability of the gait. 15,16 Kajita et al developed a running pattern for HRP-2LT equipped with toe springs. 7 Moreover, Kumar et al introduced a hybrid toe joint which is an active toe joint with a spring and a damper mechanism, to reduce the maximum required torque for this joint.…”

Section: Introductionmentioning

confidence: 99%

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Adding low-cost passive toe joints to the feet structure of SURENA III humanoid robot

Sadedel¹,

Yousefi‐Koma²,

Khadiv³

et al. 2016

Robotica

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SUMMARYAdding active toe joints to a humanoid robot structure has lots of difficulties such as mounting a small motor and an encoder on the robot feet. Conversely, adding passive toe joints is simple, since it only consists of a spring and a damper. Due to lots of benefits of implementing passive toe joints, mentioned in the literature, the goal of this study is to add passive toe joints to the SURENA III humanoid robot which was designed and fabricated at the Center of Advanced Systems and Technologies (CAST), University of Tehran. To this end, a simple passive toe joint is designed and fabricated, at first. Then, stiffness and damping coefficients are calculated using a vision-based measurement. Afterwards, a gait planning routine for humanoid robots equipped with passive toe joints is implemented. The tip-over stability of the gait is studied, considering the vibration of the passive toe joints in swing phases. The multi-body dynamics of the robot equipped with passive toe joints are presented using the Lagrange approach. Furthermore, system identification routine is adopted to model the dynamic behaviors of the power transmission system. By adding the calculated actuating torques for these two models, the whole dynamic model of the robot is computed. Finally, the performance of the proposed approach is evaluated by several simulations and experimental results. Results show that using passive toe joints reduces energy consumption of ankle and knee joints by 15.3% and 9.0%, respectively. Moreover, with relatively large values of stiffness coefficients, the required torque and power of the knee and hip joints during heel-off motion reduces as the ankle joint torque and power increases.

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“…This study also confirms Sun et al study, which states that a proper toe actuation mode reduces energy consumption of ankle joints. 16…”

Section: Benefits Of Passive Toe Jointmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Adding low-cost passive toe joints to the feet structure of SURENA III humanoid robot

Sadedel¹,

Yousefi‐Koma²,

Khadiv³

et al. 2016

Robotica

View full text Add to dashboard Cite

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“…Optimality is another important factor in locomotion that has frequently been investigated in literature [13, 14]. Another major benefit of hip retraction is reducing energy consumption.…”

Section: Introductionmentioning

confidence: 99%

Hip retraction enhances walking stability on a ramp: an equilibrium point hypothesis-based study

Bahramian

Shamsi

Towhidkhah

et al. 2019

Preprint

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Hip retraction is a phenomenon observed in human walking. The swing leg rotates 8 backward at the end of the motion. Its positive effect on motion stability was reported in the 9 literature based on some simple models for running or walking. In this study, it is shown that 10 hip retraction angle increases in humans during their ascending and descending walk on a stair. 11In previous studies, hip retraction was modeled by defining a proper motion for the swing leg. 12 According to the equilibrium point hypothesis, the central nervous system (CNS) defines only 13 the equilibrium point(s) and stiffness(es) for body joint(s) to control the human motion. Human 14 body motion emerges as its natural response as a result of the external forces and the defined 15 equilibrium points of joints. Considering the hip torque as a spring-like model with an 16 equilibrium point and stiffness, this study revealed that the hip retraction can be generated by 17 the natural response of the swing leg. Besides, the stabilizing effect of hip retraction was 18 demonstrated by a model for human`s ascending and descending walking on a ramp with a 19 range of positive and negative angles, respectively. The findings suggest that the CNS needs 20 to define equilibrium point just ahead of the stance leg to take advantage of the hip retraction 21 effect on ascending and descending walks on a ramp.22 2

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“…On the other hand, the behavior of the joints as a rotational spring have commonly been used for investigating the relationship between torque(s) and angle(s). These studies are applicable to design anthropomorphic biped robots [15–17], exoskeletons [18, 19] and prosthesis [20, 21]. Moreover, the slope of the relationship between toque(s) and angle(s) has been defined as “quasi-stiffness” which is widely used to design these systems [22].…”

Section: Introductionmentioning

confidence: 99%

A simple CPG-based model to generate human hip moment pattern in walking by generating stiffness and equilibrium point trajectories

Bahramian

Towhidkhah

Jafari

2019

Preprint

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Equilibrium point hypothesis (its developed version named as referent control theory)presents a theory about how the central nerves system (CNS) generates human movements. On the other hand, it has been shown that nerves circuits known as central pattern generators (CPG) likely produce motor commands to the muscles in rhythmic motions. In the present study, we designed a bio-inspired walking model, by coupling double pendulum to CPGs that produces equilibrium and stiffness trajectories as reciprocal and co-activation commands. As a basic model, it is has been shown that this model can regenerate pattern of a hip moment in the swing phase by high correlation ሺ ߩ ൌ 0 . 9 7 0 ሻ with experimental data. Moreover, it has been reported that a global electromyography (EMG) minima occurs in the mid-swing phase when the hip is more flexed in comparison with the other leg. Our model showed that equilibrium and actual hip angle trajectories match each other in mid-swing, similar to the mentioned posture, that is consistent with previous findings. Such a model can be used in active exoskeletons and prosthesis to make proper active stiffness and torque.controls the body?" [3, 4]. These theories explain how the CNS can release from complex calculations to control movements. According to EPH, at the muscle level, the CNS only determines a specific threshold (ߣ) for muscle [5, 6]. If actual muscle length goes beyond the defined threshold, EMG activity emerges as a result of the gap between actual and threshold muscle lengths. To control the joint, two commands are defined by the CNS: reciprocal (R) command and co-activation (C) command [7]. If joint is considered as rotational spring, R and C commands determine equilibrium point and stiffness of the joint, respectively. In accordance with the referent control theory, for multi-joint system (e.g. leg), it is assumed that initially, global R and C commands are set by CNS, then, by few-to-many mappings, r and c commands for various joints are defined. Finally, ߣ s for agonist and antagonist muscles emerged from these r and c by another mapping [8]. This hierarchical system is effective for making coordination between different joints and muscles [9]. One of the powerful experimental evidence for this hierarchical referent system is the global EMG minima [10]. When the referent (R) and actual configurations approach meet each other, a minimum EMG activity occurs for most of the muscles involved in the task [10]. This phenomena has been confirmed by many studies on various tasks such as walking and jumping [10], monkeys head movement [11], Jete in ballet dancers [12], and hammering [13]. It is shown that during stepping forward, a global EMG minima occurred during mid-swing when the hip flexion of the swing leg is slightly more than the other leg [14].On the other hand, the behavior of the joints as a rotational spring have commonly been used for investigating the relationship between torque(s) and angle(s). These studies are applicable to design anthropomorphic biped robots [15][16][...

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Adding adaptable toe stiffness affects energetic efficiency and dynamic behaviors of bipedal walking

Cited by 12 publications

References 36 publications

Adding low-cost passive toe joints to the feet structure of SURENA III humanoid robot

Adding low-cost passive toe joints to the feet structure of SURENA III humanoid robot

Hip retraction enhances walking stability on a ramp: an equilibrium point hypothesis-based study

A simple CPG-based model to generate human hip moment pattern in walking by generating stiffness and equilibrium point trajectories

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