Preliminary Study of Twisted String Actuation Through a Conduit Toward Soft and Wearable Actuation

Suthar, Bhivraj; Usman, Muhammad; Seong, Hyunseok; Gaponov, Igor; Ryu, Jee-Hwan

doi:10.1109/icra.2018.8460589

Cited by 15 publications

(13 citation statements)

References 10 publications

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“…This was done to prevent any twisting of the strings within the silicone hand itself. As suggested by previous studies [47], [48], early experiments revealed that friction between the twisted strings and the inside of the hand would prevent the strings from fully untwisting. This phenomenon resulted in significant creep in the actuation of the hand between cycles.…”

Section: A Designmentioning

confidence: 70%

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

Bombara¹,

Konda²,

Swanbeck³

et al. 2022

Preprint

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Realizing high-performance soft robotic grippers is challenging because of the inherent limitations of the soft actuators and artificial muscles that drive them. Although existing soft robotic grippers exhibit acceptable performance, their design and fabrication are still an open problem. This paper explores twisted string actuators (TSAs) to drive a soft robotic gripper. TSAs have been widely used in numerous robotic applications, but their inclusion in soft robots has been limited. The proposed design of the gripper was inspired by the human hand, with four fingers and a thumb. Tunable stiffness was implemented in the fingers by using antagonistic TSAs. The fingers' bending angles, actuation speed, blocked force output, and stiffness tuning were experimentally characterized. The gripper was able to achieve a score of 6 on the Kapandji test, and was also to achieve 31 of the 33 grasps of the Feix GRASP taxonomy. A comparison study revealed that the proposed gripper exhibited equivalent or superior performance compared to other similar grippers.

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Section: A Designmentioning

confidence: 70%

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

Bombara¹,

Konda²,

Swanbeck³

et al. 2022

Preprint

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“…The literature survey indicates some similar approaches that allow wires to contact and/or slide against one another. For instance the Twisted String Actuator generates a compression force by twisting two or more synthetic fiber strings [7] [8]. Nakamoto et al designed a 7-DoF wire-driven humanoid arm, and the wires for distal joints were squeezed at a proximal link in order to locate them close to the endorotation axis in the arm [9].…”

Section: Proposal Of Bundled Wire Drivementioning

confidence: 99%

Bundled Wire Drive: Proposal and Feasibility Study of a Novel Tendon-Driven Mechanism Using Synthetic Fiber Ropes

Endo

Wakabayashi

Nabae

et al. 2019

IEEE Robot. Autom. Lett.

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This paper proposes a new wire-driven mechanism in order to relay many ropes very simply and compactly. Ropes pass through in a joint while bundled. Synthetic fiber rope can slide and twist, exploiting its low friction coefficient. In order to use this mechanism, it is necessary to investigate the influence of sliding on tension transmission efficiency and rope strength. The results of this study reveal that it is feasible for a robot arm using this mechanism to have more than 15 joints. Sliding has little influence on rope strength. The feasibility of this system was studied through hardware experiments and its mechanical performance was evaluated by constructing a horizontally extendable manipulator with three degrees of freedom.

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“…36) leads to m= 99.29 Kg, and b = 124.77 N sm −1 for the first case scenario, and m= 24.82 Kg, and b = 311.90 N sm −1 for the second case. Considering the above values of k, m and b, the expression given by(23) was used to provide the impedance controller.…”

mentioning

confidence: 93%

“…The high transmission ratio of TSAs is attractive for robotic systems [14,35], especially for applications where energy-efficient and costeffective solutions are required, such as robot manipulators [27,25] and grippers, anthropomorphic hands [15,22,20,34], and mobile robots [37], they provide lightweight and highly customizable solutions. Additionally, TSAs have been used successfully in functions that require compact and mechanically simple transmission with some level of compliance; among these, soft robotics [8] and human-machine interaction (HMI) devices like wearable robots and exoskeletons [36,4] or haptic devices [11,33,10,26].…”

Section: Introductionmentioning

confidence: 99%

Hybrid Control Strategy for Force and Precise End Effector Positioning of a Twisted String Actuator

Rodriguez

Hosseini

Paik

2021

IEEE/ASME Trans. Mechatron.

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We propose a new control approach for the twisted string actuation (TSA) system; a hybrid control scheme consisting of two nested loops, considering the motor angle and the axial force at the clamping point of the actuator as the system outputs. We show that measuring the axial force at the base of the actuator, we can effectively estimate and compensate the coupling torque between the motor and the external load. Then, compensation of the coupling torque allows formulating a linear control law to control the angular position of the actuator and, at the same time, implement an external control loop to regulate the force applied by the actuator. Simulated and experimental results validate the proposed original control scheme. Furthermore we highlight the contributions of this work in the broader context of control of twisted string actuators.

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Preliminary Study of Twisted String Actuation Through a Conduit Toward Soft and Wearable Actuation

Cited by 15 publications

References 10 publications

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

Bundled Wire Drive: Proposal and Feasibility Study of a Novel Tendon-Driven Mechanism Using Synthetic Fiber Ropes

Hybrid Control Strategy for Force and Precise End Effector Positioning of a Twisted String Actuator

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