A Soft Bionic Gripper with Variable Effective Length

Hao, Yufei; Gong, Zizheng; Xie, Zhexin; Guan, Shaopeng; Yang, Xingbang; Wang, Tianmiao; Wen, Li

doi:10.1007/s42235-018-0017-9

Cited by 102 publications

(39 citation statements)

References 33 publications

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“…We design and fabricate an entirely soft, underwater manipulator with soft gripper as the end effector (Figure 2a) (Martinez et al, 2013; Polygerinos et al, 2015;Hao et al, 2018). The underwater soft manipulator consists four sections: two bending segments, one elongation segment, and one soft gripper (Figure 2b).…”

Section: The Underwater Soft Manipulatormentioning

confidence: 99%

“…We found that the errors are within the range of 2.7∼13.4 mm when the distances changing from 0mm to 100 mm. This error range is tolerant to the soft gripper while grasping [the tolerant deviation of gripper and objects that led to successful grasp (Hao et al, 2018)]. According to the kinematic model, simulation on the workspace of the soft arm is illustrated as Figure 7.…”

Section: Kinematic Model Validation Trajectory Planning and Workpamentioning

confidence: 99%

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An Opposite-Bending-and-Extension Soft Robotic Manipulator for Delicate Grasping in Shallow Water

et al. 2019

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Collecting seafood animals (such as sea cucumbers, sea echini, scallops, etc.) cultivated in shallow water (water depth: ∼30 m) is a profitable and an emerging field that requires robotics for replacing human divers. Soft robotics have several promising features (e.g., safe contact with the objects, lightweight, etc.) for performing such a task. In this paper, we implement a soft manipulator with an opposite-bending-and-extension structure. A simple and rapid inverse kinematics method is proposed to control the spatial location and trajectory of the underwater soft manipulator's end effector. We introduce the actuation hardware of the prototype, and then characterize the trajectory and workspace. We find that the prototype can well track fundamental trajectories such as a line and an arc. Finally, we construct a small underwater robot and demonstrate that the underwater soft manipulator successfully collects multiple irregular shaped seafood animals of different sizes and stiffness at the bottom of the natural oceanic environment (water depth: ∼10 m).

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Section: The Underwater Soft Manipulatormentioning

confidence: 99%

Section: Kinematic Model Validation Trajectory Planning and Workpamentioning

confidence: 99%

An Opposite-Bending-and-Extension Soft Robotic Manipulator for Delicate Grasping in Shallow Water

et al. 2019

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“…Compared to the soft actuators, such as those that are tendon driven using cables or shape memory alloy [ 13 , 14 ], electrically driven using electroactive polymers [ 15 , 16 ], or thermally driven using hydrogels [ 17 , 18 ], soft pneumatic actuators are widely used. These soft pneumatic actuators can achieve high bearing capacity and fast responses, such as a fiber-reinforced soft actuator [ 19 , 20 , 21 ] and a bellows-type soft actuator [ 22 , 23 , 24 ]. A variety of soft grippers actuated by soft pneumatic actuators have been developed, which can grip not only regular-shaped objects such as cubes and cylinders, but also irregular-shaped objects such as keys, mice, and scissors [ 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Modeling of a Soft-Rigid Gripper Actuated by a Linear-Extension Soft Pneumatic Actuator

Cheng

Jia

et al. 2021

Sensors

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Soft robot has been one significant study in recent decades and soft gripper is one of the popular research directions of soft robot. In a static gripping system, excessive gripping force and large deformation are the main reasons for damage of the object during the gripping process. For achieving low-damage gripping to the object in static gripping system, we proposed a soft-rigid gripper actuated by a linear-extension soft pneumatic actuator in this study. The characteristic of the gripper under a no loading state was measured. When the pressure was >70 kPa, there was an approximately linear relation between the pressure and extension length of the soft actuator. To achieve gripping force and fingertip displacement control of the gripper without sensors integrated on the finger, we presented a non-contact sensing method for gripping state estimation. To analyze the gripping force and fingertip displacement, the relationship between the pressure and extension length of the soft actuator in loading state was compared with the relationship under a no-loading state. The experimental results showed that the relative error between the analytical gripping force and the measured gripping force of the gripper was ≤2.1%. The relative error between analytical fingertip displacement and theoretical fingertip displacement of the gripper was ≤7.4%. Furthermore, the low damage gripping to fragile and soft objects in static and dynamic gripping tests showed good performance of the gripper. Overall, the results indicated the potential application of the gripper in pick-and-place operations.

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“…For example, a soft pneumatic gripper was successfully applied to collect multiple irregular shaped seafood animals of different sizes and stiffness at the bottom of the natural oceanic environment 2 ; a soft pneumatic gripper can recognize the sizes of objects and sort the objects with different sizes 3 ; a soft gripper actuated by ionic polymermetal composite can manipulate micro object less than 1 mm in diameter and macro-sized object within 10 mm diameter 4 ; a shape-memory alloy (SMA)-based soft gripper can actively achieve multiple postures to grasp objects with deformable shapes and varying shapes with a large range of weight. 5 Usually, soft robotic grippers are actuated by different actuation techniques, for example, pneumatic actuation, 3,[6][7][8] cable-driven actuation, 9,10 electroactive polymer (EAP, an abbreviation for electroactive polymers, which can change its shape or size in response to electrical stimulation.) actuation, [11][12][13] and SMA actuation.…”

Section: Introductionmentioning

confidence: 99%

A novel design of shape-memory alloy-based soft robotic gripper with variable stiffness

Liu

Hao

Zhang

et al. 2020

International Journal of Advanced Robotic Systems

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Soft robotic grippers with compliance have great superiority in grabbing objects with irregular shape or fragility compared with traditional rigid grippers. The main limitations of such systems are small grasping force resulted from properties of soft actuators and lacking variable stiffness of soft robotic grippers, which prevent them from a larger wide range of applications. This article proposes a shape-memory alloy (SMA)-based soft gripper with variable stiffness composed of three robotic fingers for grasping compliantly at low stiffness and holding robustly at high stiffness. Each robotic finger mainly consisted of stiff parts and two variable stiffness joints is installed on the base with a specific angle. The paraffin as a variable stiffness material in the joint can be heated or cooled to change the stiffness of the robotic fingers. Results of experiments have shown that a single robotic finger can approximately achieve 18-fold stiffness enhancement. Each finger with two joints can actively achieve multiple postures by both changing the corresponding stiffness of joints and actuating the SMA wire. Based on these principles, the gripper can be applied to grasp objects with different shapes and a large range of weights, and the maximum grasping force of the gripper is increased to about 10 times using the variable stiffness joints. The final experiment is conducted to validate variable stiffness of the proposed soft grippers grasping an object.

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A Soft Bionic Gripper with Variable Effective Length

Cited by 102 publications

References 33 publications

An Opposite-Bending-and-Extension Soft Robotic Manipulator for Delicate Grasping in Shallow Water

An Opposite-Bending-and-Extension Soft Robotic Manipulator for Delicate Grasping in Shallow Water

Modeling of a Soft-Rigid Gripper Actuated by a Linear-Extension Soft Pneumatic Actuator

A novel design of shape-memory alloy-based soft robotic gripper with variable stiffness

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