Optimal design and comparative study of two antagonistically actuated tensegrity joints

Muralidharan, Vimalesh; Wenger, Philippe

doi:10.1016/j.mechmachtheory.2021.104249

Cited by 26 publications

(25 citation statements)

References 23 publications

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“…The same behavior was also reported for a 2R joint with offsets that represents one circle pure rolling over another [12]. In contrast, for an anti-parallelogram joint, that is equivalent to one ellipse pure rolling over another, the antagonistic actuation has a positive influence on the joint stiffness [11], just as in the biological joints. Thus, drawing inspiration from the anti-parallelogram mechanism, the goal of this work is to find all the four-bar mechanisms with symmetric limbs, that exhibit an increase in stiffness with antagonistic actuation by cables.…”

Section: Introductionsupporting

confidence: 71%

“…There are other joints where stiffness modulation can be achieved without in-series springs, by only varying the cable forces, see e.g., the tensegrity-inspired joints presented in [11]. It was found that with the increase in antagonistic cable forces, the revolute joint experiences a drop in stiffness, which was a counterintuitive result [11].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Antagonistic Cable Actuation on the Stiffness of Symmetric Four-Bar Mechanisms

Muralidharan

Chevallereau

Wenger

et al. 2023

Mechanisms and Machine Science

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In biological systems, the joints are actuated antagonistically by muscles that can be moved coherently to achieve the desired displacement and co-activated with appropriate forces to increase the joint stiffness. Taking inspiration from this, there is an interest to develop bio-inspired robots that are suitable for both low-stiffness and high-stiffness tasks. Mechanisms actuated by antagonist cables can be a reasonable approximation of biological joints. A study on the antiparallelogram mechanism showed that the antagonistic forces (> 0) have a positive influence on its stiffness, similar to the biological joints. In this work, more general symmetric four-bar mechanisms with crossed/regular limbs, larger/smaller top and base bars are investigated for this property. Totally, six different types of mechanisms were identified and the limits of movement were determined in each case. Inside these limits, it was found through numerical simulations that the cable forces have a positive (resp. negative) influence on the stiffness of the mechanism when its limbs are crossed (resp. regular). This shows that the symmetric fourbar mechanisms with crossed limbs are suitable for building bio-inspired joints/robots, while their counterparts cannot serve this purpose. Among these, the anti-parallelogram mechanism offers the largest orientation range of ] − π, π[ for the top bar w.r.t. its base and is thus the best choice.

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Section: Introductionsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Effect of Antagonistic Cable Actuation on the Stiffness of Symmetric Four-Bar Mechanisms

Muralidharan

Chevallereau

Wenger

et al. 2023

Mechanisms and Machine Science

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“…As compared with simple revolute joints, X-joints do not have a fixed rotation axis, a common feature in biological joints [21,9]. Moreover, they have a number of advantages such as larger rotation ranges [4] and larger variations of stiffness [22].…”

Section: Introductionmentioning

confidence: 99%

Identification and Control of a 3-X Cable-Driven Manipulator Inspired From the Bird’s Neck

Fasquelle

Khanna

Chevallereau

et al. 2021

Journal of Mechanisms and Robotics

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This paper is devoted to the control and identification of a manipulator with three anti-parallelogram joints in series, referred to as X-joints. Each X-joint is a tensegrity one-degree-of-freedom mechanism antagonistically actuated with cables and springs in parallel. As compared to manipulators built with simple revolute joints in series, manipulators with tensegrity X-joint offer a number of advantages, such as an intrinsic stability, variable stiffness and lower inertia. This design was inspired by the musculosleketon architecture of the bird neck, which is known to be very dextrous. A test-bed prototype is presented and used to test computed torque control laws. Friction and cable elasticity are modelled and identified. Their effect on the performance of control laws is analyzed. It is shown that in the context of antagonistic actuation and light weight design, friction plays a leading role and the significance of modelling cable elasticity is discussed

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“…However, it is necessary to prepare for possible failures in the geared rolling units. Rolamite using flexures or X-joints using an anti-parallelogram, which can transmit a large torque, can be considered as a replacement for the gears [9,19]. On the other hand, it is required to verify experimentally whether the X-joint mechanism can be applied without modifying the existing cable actuation [20,21].…”

Section: Discussionmentioning

confidence: 99%

Design and Verification of Parallelogram Mechanism With Geared Unit Rolling Joints for Reliable Wiring

Suh

Choi

2023

IEEE Robot. Autom. Lett.

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The structure of 1-DOF joints used in existing robots is generally a revolute or a prismatic joint. However, recently, attempts have been made to apply rolling joints to reduce the size and weight of surgical and humanoid robots. In this study, to take advantages of wire routing through robot joints, a new method for applying geared rolling units to a parallelogram mechanism is proposed. First, a kinematic analysis of the proposed gear-based mechanism is explained in comparison with the existing pivot-based mechanism. In addition, the importance of the radii of the gears is verified through force analysis to prevent damage to the applied gears, as well as through the analysis of actuation torque and singular positions, in which the parallelogram can convert into an antiparallelogram. The effect of stable wiring was verified through an experiment using a cable-driven prototype. Consequently, the proposed parallelogram mechanism composed of rolling units is expected to be applied to various robot configurations owing to its advantages.Index Terms-Mechanism design, actuation and joint mechanisms, tendon/wire mechanism, kinematics NRF-2020R1C1C1008707, No. 2022.

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Optimal design and comparative study of two antagonistically actuated tensegrity joints

Cited by 26 publications

References 23 publications

Effect of Antagonistic Cable Actuation on the Stiffness of Symmetric Four-Bar Mechanisms

Effect of Antagonistic Cable Actuation on the Stiffness of Symmetric Four-Bar Mechanisms

Identification and Control of a 3-X Cable-Driven Manipulator Inspired From the Bird’s Neck

Design and Verification of Parallelogram Mechanism With Geared Unit Rolling Joints for Reliable Wiring

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