Robust hopping based on virtual pendulum posture control

Sharbafi, Maziar Ahmad; Maufroy, Christophe; Ahmadabadi, Majid Nili; Yazdanpanah, Mohammad Javad; Seyfarth, André

doi:10.1088/1748-3182/8/3/036002

Cited by 49 publications

(48 citation statements)

References 30 publications

(68 reference statements)

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“…In this context, the model of Shafarbi and colleagues [126] provides a good comparison with our model as it addresses directly hopping. Their model, which they called XTSLIP, extends the SLIP model by including an upper torso and a leg (both with mass).…”

Section: Discussionmentioning

confidence: 96%

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From Spontaneous Motor Activity to Coordinated Behaviour: A Developmental Model

2014

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In mammals, the developmental path that links the primary behaviours observed during foetal stages to the full fledged behaviours observed in adults is still beyond our understanding. Often theories of motor control try to deal with the process of incremental learning in an abstract and modular way without establishing any correspondence with the mammalian developmental stages. In this paper, we propose a computational model that links three distinct behaviours which appear at three different stages of development. In order of appearance, these behaviours are: spontaneous motor activity (SMA), reflexes, and coordinated behaviours, such as locomotion. The goal of our model is to address in silico four hypotheses that are currently hard to verify in vivo: First, the hypothesis that spinal reflex circuits can be self-organized from the sensor and motor activity induced by SMA. Second, the hypothesis that supraspinal systems can modulate reflex circuits to achieve coordinated behaviour. Third, the hypothesis that, since SMA is observed in an organism throughout its entire lifetime, it provides a mechanism suitable to maintain the reflex circuits aligned with the musculoskeletal system, and thus adapt to changes in body morphology. And fourth, the hypothesis that by changing the modulation of the reflex circuits over time, one can switch between different coordinated behaviours. Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways. Hopping is used as a case study of coordinated behaviour. Our results show that reflex circuits can be self-organized from SMA, and that, once these circuits are in place, they can be modulated to achieve coordinated behaviour. In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.

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Section: Discussionmentioning

confidence: 96%

“…it assumes no energy losses due to contacts with the ground) but such an assumption has been relaxed in subsequent extensions [124]. The SLIP model has been used (and extended) to analyse energy efficiency and behavioural stability during running [123], walking [125], hopping [126] as well as during behavioural transitions [127].…”

Section: Discussionmentioning

confidence: 99%

From Spontaneous Motor Activity to Coordinated Behaviour: A Developmental Model

2014

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“…The stability is analyzed considering the n-step periodic motion which means having the same CoM states after n steps. Since with the proposed modeling and control approach, in many cases we obtain ultimate boundedness (especially for n > 2) instead of asymptotic stability, Kstep stability is utilized [18], [16]. The controlled system is K-step stable (ultimately bounded) if it does not fall and never leaves a certain neighborhood of the periodic response in K steps.…”

Section: System Analysismentioning

confidence: 99%

SLIP with swing leg augmentation as a model for running

Rashty

Sharbafi

Seyfarth

2014

2014 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Abstract-Swing leg adjustment, repulsive leg function and balance are key elements in the control of bipedal locomotion. In simple gait models like spring-loaded inverted pendulum (SLIP), swing leg control can be applied to achieve stable running. The aim of this study is to investigate the ability of pendulum like swing leg motion for stabilizing running and reproducing a desired (human like) gait pattern. The employed running model consists of two sub-models: SLIP model for the stance phase and a pendulum based control for the swing phase. It is shown that with changing the pendulum length at each step, stable running gaits with widely different performances are achieved. The body vertical speed at take off is utilized as feedback information to tune the pendulum length as the control parameter. In particular, the effect of the pendulum length adjustment on the motion characteristics like horizontal speed, apex height and the stabilized system energy will be investigated. With this method key features of the human like swing leg motion e.g. leg retraction can be reproduced. Higher speeds correspond larger angular motion of each leg which is in agreement with experimental results in previous studies. The presented model also explains the swing-leg to stance-leg interaction mechanism which was not addressed in the underlying SLIP model. This conceptual model can be considered as a functional mechanical template for legged locomotion and can be used to build more complex models, e.g. having segmented legs or an upper body.

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“…The results revealed the advantages of using the force feedback 55 in reducing the human metabolic cost of walking. From biological point of view, studies 56 on normal and pathological gait demonstrated that humans also use proprioceptive 57 feedback signals (e.g., detecting load as a complex parameter, recorded by very different 58 types of receptors) in locomotion control [39,40]. In addition to ability of measuring the 59 load (e.g., body weight) in humans, high dependency of compensatory leg muscle 60 activation was demonstrated experimentally [41].…”

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confidence: 99%

“…The VPP model: The VPP which is observed in human and animal gaits is a point 123 on the upper body above the CoM (center of mass) at which the ground reaction forces 124 are intersecting during the stance phase [50]. This concept was already applied to 125 predict hip torque required for posture control using template modelling for different 126 gaits [54][55][56]. Template models are simple conceptual models using basic mechanical 127 elements (e.g., mass, spring) which can explain some important features of 128 locomotion [33].…”

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confidence: 99%

From a biological template model to gait assistance with an exosuit

Firouzi

Davoodi

Bahrami

et al. 2020

Preprint

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By invention of soft wearable assistive devices, known as exosuits, a new aspect in assisting unimpaired subjects is introduced. In this study, we designed and developed an exosuit with compliant biarticular thigh actuators, called BAExo. Unlike common method of using rigid actuators in exosuits, the BAExo is made of serial elastic actuators (SEA) resembling artificial muscles (AM). This bioinsipred design is complemented by the novel control concept of using the ground reaction force to adjust these AMs' stiffness in the stance phase. By locking the motors in the swing phase the SEAs will be simplified to passive biarticular springs, which is sufficient for leg swinging. The key concept in our design and control approach is synthesizing human locomotion to develop assistive device, instead of copying the outputs of human motor control. Analysing human walking assistance using an experiment-based OpenSim model demonstrates the advantages of the proposed design and control of BAExo, regarding metabolic cost reduction and efficiency of the system. In addition, pilot experiments with the recently developed BAExo hardware support the applicability of the introduced method. Author summaryAging and mobility of elderly people are of crucial concern in developed countries. The U.S. Census Bureau reports that by the middle of the 21st century, about 80 million Americans will be 65 or older. According to the group's research, medical costs resulting from falls by the elderly are expected to approach $32.4 billion by 2020. Therefore, assistance of elderly people and making the assistive devices more intelligent is a need in near future. However, this is not the only application of assistive devices. Exosuits, as soft wearable robots, introduced a new aspect in assisting a large range of population, even healthy young people. We introduce a novel design and control method for a new exosuit. As the research in the field of wearable assistive devices is growing in recent years and its application in daily life becomes more evident for the society, such studies with a unique view in design and control could have a significant impact. Our proposed biologically inspired approach could be potentially applied to other exosuits. Introduction 1 Lower limb exoskeletons for assisting people with decreased locomotion abilities has 2 attracted the attention of researchers [1] and the healthcare industry [2, 3]. Assistive 3 March 21, 2020 1/24 6 about aging. For example, by aging, muscle force and power decrease and to reduce the 7 cost of elderly and patients locomotion, assistive devices are demanded [6, 7]. 8 One of the common goals of assistive device designers is to reduce the metabolic cost 9 of locomotion [8]. This feature is important in all above-mentioned cases and situations. 10 In the last couple of years researchers have succeeded in significantly improving the 11 metabolic cost reduction in human gaits using powered exoskeletons [1,[9][10][11]. 12Powered exoskeletons can be categorized as (1) traditional ones with rigid stru...

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Robust hopping based on virtual pendulum posture control

Cited by 49 publications

References 30 publications

From Spontaneous Motor Activity to Coordinated Behaviour: A Developmental Model

From Spontaneous Motor Activity to Coordinated Behaviour: A Developmental Model

SLIP with swing leg augmentation as a model for running

From a biological template model to gait assistance with an exosuit

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