Exploiting Bistability for High Force Density Reflexive Gripping

Jitosho, Rianna; Choi, Kevin; Foris, Adam; Mazumdar, Anirban

doi:10.1109/icra.2019.8794393

Cited by 8 publications

(4 citation statements)

References 35 publications

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“…Besides, the bending of all three fingers may not synchronize due to the fast response process. This is also reported in existing bistable gripper designs [18,23].…”

Section: Application Of Graspingsupporting

confidence: 76%

“…Inspired by the Venus Flytrap, bistable structures have been explored to enhance the performance of the soft actuators. Among these, carbon-fiber reinforced polymer (CFRP) [16][17][18], silicone layer [19,20], dielectric elastomer [21,22], spring steel strip [23] were utilized in the design of bistable actuators. The actuation mechanism for aforementioned structures are magnetic actuation, shape memory alloy actuation (SMA), pneumatic actuation, piezoelectric actuation, electrical actuation, gear actuation, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Bio-inspired soft bistable actuator with dual actuations

Wang

Zhou

Kang

et al. 2021

Smart Mater. Struct.

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Soft bending actuators, as one of the most important components of soft robotics, have attracted significantly increasing attention due to their robustness, compliance, inherent safety, and ease of manufacture. However, the key disadvantages can be the low output force, slow response speed, large deformation and vibration, which can potentially be addressed by introducing a bistable mechanism enabled by a prestressed steel shell. This work proposes a novel soft actuator with bistable property, which can maintain the predefined initial state and enhance bending motion at the corresponding stable state. A novel dual-actuation mechanism, which utilises pneumatic pressure for closing and tendon-driven for opening process, is proposed for autonomous transition between both states, and for a fast response. Mathematical model is proposed and compared with the experimental result for triggering pressure, which serves as a threshold to activate the transition of the stable state. Experimental results also indicate that closing and opening speeds are enhanced by 9.82% and more than ten times, respectively, as compared with the existing pneumatic bistable reinforced actuator design. Mathematical and experimental results suggest that a programmable bending angle at the second stable state can also be achieved by adjusting the preset tendon extension. The tendon arrangement also acts as a passive damping mechanism to reduce the oscillation while closing. The damping ratio is increased by more than four times, indicating that the oscillation decay is significantly accelerated for quick stabilization. Finally, a three-finger soft gripper is developed based on the proposed actuator design, which demonstrates promising performance in grasping objects with various shapes and sizes. The experimental results also show that the proposed bistable gripper can grasp the object with a weight up to 2067 g, which is more than 17 times heavier than that of three actuators.

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“…Besides, the bending of all three fingers may not synchronize due to the fast response process. This is also reported in existing bistable gripper designs [18,23].…”

Section: Application Of Graspingsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Bio-inspired soft bistable actuator with dual actuations

Wang

Zhou

Kang

et al. 2021

Smart Mater. Struct.

View full text Add to dashboard Cite

show abstract

“…Despite the versatility of these grippers, however, ungrasping an object remains a challenge for them. As a result, for most robotic manipulators, binary actuation is required in the form of SMA [24], pneumatics [25], or magnets [26] to release the object.…”

Section: Introductionmentioning

confidence: 99%

Push-On Push-Off: A Compliant Bistable Gripper with Mechanical Sensing and Actuation

McWilliams

Yuan

Friedman

et al. 2021

2021 IEEE 4th International Conference on Soft Robotics (RoboSoft)

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Grasping is an essential task in robotic applications and is an open challenge due to the complexity and uncertainty of contact interactions. In order to achieve robust grasping, systems typically rely on precise actuators and reliable sensing in order to control the contact state. We propose an alternative design paradigm that leverages contact and a compliant bistable mechanism in order to achieve "sensing" and "actuation" purely mechanically. To grasp an object, the manipulator holding our end effector presses the bistable mechanism into the object until snap-through causes the gripper to enclose it. To release the object, the tips of the gripper are pushed against the ground, until rotation of the linkages causes snap-through in the other direction. This push-on pushoff scheme reduces the complexity of the grasping task by allowing the manipulator to automatically achieve the correct grasping behavior as long as it can get the end effector to the correct location and apply sufficient force. We present our dynamic model for the bistable gripping mechanism, propose an optimized result, and demonstrate the functionality of the concept on a fabricated prototype. We discuss our stiffness tuning strategy for the 3D printed springs, and verify the snapthrough behavior of the system using compression tests on an MTS machine.

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“…This PBRA design uses a fold-based structure modified based on [3] together with a prestressed steel shell (PSS) which has been explored for use in gripping application [26,27]. The PSS has the same bistable mechanism as the Venus Flytrap which changes the shape of its leaves from convex to concave for opening and closing to catch insects [28].…”

Section: Introductionmentioning

confidence: 99%

A soft pneumatic bistable reinforced actuator bioinspired by Venus Flytrap with enhanced grasping capability

2020

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Soft actuators, as an important part of soft robotics, have attracted significant attention due to their inherent compliance, flexibility and safety. However, low capacity in force and load limits their applications. Prestored elastic energy can improve the capacity in output force and load of soft actuators. This work introduces a soft pneumatic bistable reinforced actuator inspired by the Venus Flytrap's bistable mechanism that allows for the storage of elastic energy. The proposed actuator consists of two separated 3D-printed actuation chambers that are attached to a central prestressed steel shell to achieve bistability. The pressure triggering the pneumatic bistable reinforced actuator from one stable state to the other is derived and validated by experiments. Further experimental comparisons between the proposed actuator and a dual chamber actuator show that the proposed design significantly improves the block tip force, load capacity and stiffness. The pneumatic bistable reinforced actuator also demonstrates superior performance in the actuation speed and bending angle under the same input pressure. Finally, a two-finger gripper is developed using the proposed actuator, which is demonstrated to grasp and hold various objects.

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Exploiting Bistability for High Force Density Reflexive Gripping

Cited by 8 publications

References 35 publications

Bio-inspired soft bistable actuator with dual actuations

Bio-inspired soft bistable actuator with dual actuations

Push-On Push-Off: A Compliant Bistable Gripper with Mechanical Sensing and Actuation

A soft pneumatic bistable reinforced actuator bioinspired by Venus Flytrap with enhanced grasping capability

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