Moment Arm Analysis of the Biarticular Actuators in Compliant Robotic Leg Carl

Nejadfard, Atabak; Schütz, Steffen; Mianowski, K.; Vonwirth, Patrick; Berns, Karsten

doi:10.1007/978-3-319-95972-6_37

Cited by 8 publications

(12 citation statements)

References 15 publications

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“…In another example of a simple swing leg model, the (rest) length of biarticular thigh springs was found to linearly correlate with the target swing leg angle [41]. However, in all these applications, biarticular moment arm ratios are an important factor determining the functional contribution of the biarticular actuator or spring, as shown in the CARL robot [142]. Proper design of moment arm ratios and spring properties (e.g.…”

Section: Control Embodiment Via Compliance and Biarticular Mechanismmentioning

confidence: 99%

“…Proper design of moment arm ratios and spring properties (e.g. spring stiffness or rest length) can thus be used as design parameters to determine the desired limb behaviour and incorporate a bioinspired control embodiment strategy in robotic systems [40,117,124,142,143].…”

Section: Control Embodiment Via Compliance and Biarticular Mechanismmentioning

confidence: 99%

“…SEA or PAM, realize biarticularity. Often, engineers use the structural compliance or muscle moment arms as design parameters to generate a desired leg behaviour [40,117,124,142,143,174]. In assistive devices, like prostheses or exoskeletons, walking economy of the wearer or efficiency of the device could be improved [155,156,162,167].…”

Section: Applicationsmentioning

confidence: 99%

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Biarticular muscles in light of template models, experiments and robotics: a review

Schumacher

Sharbafi

Seyfarth

et al. 2020

J. R. Soc. Interface.

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Leg morphology is an important outcome of evolution. A remarkable morphological leg feature is the existence of biarticular muscles that span adjacent joints. Diverse studies from different fields of research suggest a less coherent understanding of the muscles' functionality in cyclic, sagittal plane locomotion. We structured this review of biarticular muscle function by reflecting biomechanical template models, human experiments and robotic system designs. Within these approaches, we surveyed the contribution of biarticular muscles to the locomotor subfunctions (stance, balance and swing). While mono-and biarticular muscles do not show physiological differences, the reviewed studies provide evidence for complementary and locomotor subfunction-specific contributions of mono-and biarticular muscles. In stance, biarticular muscles coordinate joint movements, improve economy (e.g. by transferring energy) and secure the zig-zag configuration of the leg against joint overextension. These commonly known functions are extended by an explicit role of biarticular muscles in controlling the angular momentum for balance and swing. Human-like leg arrangement and intrinsic (compliant) properties of biarticular structures improve the controllability and energy efficiency of legged robots and assistive devices. Future interdisciplinary research on biarticular muscles should address their role for sensing and control as well as non-cyclic and/or non-sagittal motions, and non-static moment arms. royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 17: 20180413 royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 17: 20180413

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Section: Control Embodiment Via Compliance and Biarticular Mechanismmentioning

confidence: 99%

Section: Control Embodiment Via Compliance and Biarticular Mechanismmentioning

confidence: 99%

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Biarticular muscles in light of template models, experiments and robotics: a review

Schumacher

Sharbafi

Seyfarth

et al. 2020

J. R. Soc. Interface.

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“…The planar robotic leg Carl is designed based on the human morphology. 8,9 Carl consists of three conventional mono-articular actuators (MoAs), denoted as A H , A K and A A , acting on the hip, knee and ankle joints, respectively, see Fig. 1b.…”

Section: Design Of Compliant Robotic Leg (Carl)mentioning

confidence: 99%

Technical advantages and disadvantages of biarticular actuators in bipedal robots

2020

Robots in Human Life

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The practical advantages of redundant biarticular actuators in bipedal robotic systems are demonstrated and reviewed. The major physiological role of biarticular muscles indeed can be successfully replicated in robotic systems by transferring power from heavy upper leg segments to the lower limb joints. As hypothesized in biomechanics, biarticular actuators contribute to the efficiency of explosive movements in robotic systems similar to the human body. Despite the added weight of the redundant actuators, redundancy enables the proper selection of mono-articular actuators so that all the actuators operate in their optimum working points. It is important to notice that the energetic benefits of biarticular muscles have not been identified during human walking locomotion. Therefore the efficiency gain due to the addition of biarticulars can be limited in bipedal walking. Still, the technical advantage of the bi-articulation facilitates the mass distribution of the actuators over leg segments, specifically by reducing the mass of the shank segment in the robotic leg.

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“…As a consequence, we realized the significance of MAP which shapes the interaction of the muscles and determines the efficiency of AFD and overall movement. Due to the interconnected nature of the actuation kinematic network, an analytical approach was introduced to investigate the physiological influence of MAP in [5], particularly for biarticular muscles (BiMs).…”

Section: A Mmentioning

confidence: 99%

Design of the musculoskeletal leg $\rm C \tiny{\rm ARL}$ based on the physiology of mono-articular and biarticular muscles in the human leg

et al. 2019

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In a lower extremity musculoskeletal leg, the actuation kinematics define the interaction of the actuators with each other and the environment. Design of such a kinematic chain is challenging due to the existence of the redundant biarticular actuators which simultaneously act on two joints, generating a parallel mechanism. Actuator kinematics is mainly dependent on the moment arm profile of the actuation system. It is a common practice to select a constant moment arm value for robotic actuation system; nevertheless, biological muscles feature a distinctive nonlinear moment arm profile that has been ignored in the design of the musculoskeletal robots. In this paper, we propose a design paradigm for compliant robotic leg Carl based on the direct replication of the human leg anatomy. The resulting mechanical system should (a) demonstrate a similar moment arm profile as in leg musculature, (b) exhibit expected physiological behavior of the muscles, (c) provide insight into the interaction of the actuators and possible improvement in the efficiency of the movements. We provide a comprehensive analysis of the moment arm profile of the leg musculature. The actuator kinematics of the designed leg is validated by comparing the contraction velocities of the muscles and actuators. The biological characteristics of the actuators are analyzed using the jump experiment data conducted on the previous version of the leg. The major physiological characteristics of the biarticular muscles, ligamentous action, and distal power transfer, is successfully demonstrated by the robotic leg. Our analysis demonstrates that the proposed structural design of the actuation system can improve the mechanical efficiency of this particular jump experiment up to 16% compared to the leg without actuator redundancy. Compared to the previous version of the leg, by only modifying the moment arm profiles, we can achieve an efficiency improvement of approximately 5%.

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Moment Arm Analysis of the Biarticular Actuators in Compliant Robotic Leg Carl

Cited by 8 publications

References 15 publications

Biarticular muscles in light of template models, experiments and robotics: a review

Biarticular muscles in light of template models, experiments and robotics: a review

Technical advantages and disadvantages of biarticular actuators in bipedal robots

Design of the musculoskeletal leg $\rm C \tiny{\rm ARL}$ based on the physiology of mono-articular and biarticular muscles in the human leg

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