Mechanics of a pressure-controlled adhesive membrane for soft robotic gripping on curved surfaces

Song, Suk‐Ho; Drotlef, Dirk-M.; Paik, Jamie; Majidi, Carmel; Sitti, Metin

doi:10.1016/j.eml.2019.100485

Cited by 19 publications

(10 citation statements)

References 41 publications

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“…To evaluate the effectiveness of the gripper, pull-off tests 18,34,38,41 were conducted using a materials testing machine (Instron 5969). During the tests, the gripper was attached to a -10 N load cell that was mounted to the crosshead of the Instron, and an acrylic substrate was fixed in place directly below.…”

Section: Methodsmentioning

confidence: 99%

“…As a result, pull-off force is often used as a metric for evaluating the efficacy of adhesion-based grippers. 18,34,38,40,41 To test the effectiveness of our gripper and help guide its future design, we conduct experiments to measure pull-off force as a function of various parameters. Additionally, a finite element model is developed to simulate the behavior of the gripper.…”

Section: Introductionmentioning

confidence: 99%

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Versatile Soft Robot Gripper Enabled by Stiffness and Adhesion Tuning via Thermoplastic Composite

et al. 2022

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Within the field of robotics, stiffness tuning technologies have potential for a variety of applications-perhaps most notably for robotic grasping. Many stiffness tuning grippers have been developed that can grasp fragile or irregularly shaped objects without causing damage and while still accommodating large loads. In addition to limiting gripper deformation when lifting an object, increasing gripper stiffness after contact formation improves load sharing at the interface and enhances adhesion. In this study, we present a novel stiffness and adhesion tuning gripper, enabled by the thermally induced phase change of a thermoplastic composite material embedded within a silicone contact pad. The gripper operates by bringing the pad into contact with an object while in its heated, soft state, and then allowing the pad to cool and stiffen to form a strong adhesive bond before lifting the object. Pull-off tests conducted using the gripper show that transitioning from a soft to stiff state during grasping enables up to 6 • increase in adhesion strength. Additionally, a finite element model is developed to simulate the behavior of the gripper. Finally, pick-and-place demonstrations are performed, which highlight the gripper's ability to delicately grasp objects of various shapes, sizes, and weights.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Versatile Soft Robot Gripper Enabled by Stiffness and Adhesion Tuning via Thermoplastic Composite

et al. 2022

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“…Dry fribrillar adhesives use patterned arrays of soft microstructures to induce Van der Waals interactions between the substrate and the microstructure. [19][20][21][22][23] This approach provides high strength-to-weight performance and requires no energy to maintain adhesion but is limited to low force angles. [24] In addition, the adhesive strength of these approaches degrades on dirty surfaces.…”

Section: Doi: 101002/aisy202100001mentioning

confidence: 99%

Gas‐Lubricated Vibration‐Based Adhesion for Robotics

Weston-Dawkes

Adibnazari

et al. 2021

Advanced Intelligent Systems

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Controllable adhesion, the ability to selectively attach or detach from a surface, is an essential capability for many engineered systems, such as material processing equipment, wall-climbing robots, and pick-and-place machinery. Robots capable of controllable adhesion have applications for inspection and repair, surveillance, and exploration of environments unsuitable for humans. [1,2] A variety of controllable adhesion techniques have been proposed to enable these use cases, including methods relying on pneumatic, electromagnetic, and dry fibrillar adhesive forces between a robot and a surface. While existing techniques are often effective, they usually require relatively heavy and energyconsuming components and/or intrinsically link high normal and shear adhesion.In this work, we develop an adhesion mechanism that relies on the fluidmediated adhesive force between an oscillatory plate and a surface. This lightweight, low-power mechanism provides high normal-but low-shear-adhesion, making it uniquely suitable for robotic applications including mobile robots and some manipulation tasks.Previous approaches have used active pneumatic adhesion (i.e., suction) [3,4] or strong electromagnets or permanent magnets [5] to demonstrate high adhesive stresses to enable wall climbing for relatively heavy systems (e.g., σ max ¼ 20.1 kPa for an individual suction unit weighing 0.8 kg [6] ). However, these approaches are, in general, limited to nonporous and ferromagnetic surfaces, respectively. In addition to surface restrictions, these systems usually require additional bulky hardware (i.e., traditional pumps and magnets). Despite these disadvantages, some pneumatic and electromagnetic approaches do have the advantage that they do not require direct contact with surfaces for adhesion. Thus, adhesion can be maintained while the manipulator or mobile robot smoothly slides across the adhering surface. This non-or light-contact mode of adhesion may be advantageous for mobile inspection robots that have to move easily across surfaces.Active pneumatic adhesion is advantageous in that pumps are commercially available and are relatively straightforward to control and integrate into a physical system. However, at small scales, these advantages are lost as the manufacturing of micro-electromechanical system micropumps [7] requires specialized high-precision equipment. Some studies have investigated

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“…Being made of soft material, they can conform to the shape of the target object, distributing the stress more evenly. Multiple different soft grippers have been proposed: bioinspired suction cups [ 2 , 3 ], grippers with controlled adhesive surfaces [ 4 – 8 ], grippers with multiple soft fingers [ 9 – 13 ], grippers based on state change [ 14 , 15 ] and so-called jamming grippers [ 16 – 19 ], which envelope the target object with a switchable material that turns from soft to rigid (e.g. granular material [ 16 , 17 ] or magnetorheological fluids (MR fluids) [ 18 – 20 ]).…”

Section: Introductionmentioning

confidence: 99%

Magnetically switchable soft suction grippers

Koivikko

Drotlef

Sitti

et al. 2021

Extreme Mechanics Letters

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Grasping is one of the key tasks for robots. Gripping fragile and complex three-dimensional (3D) objects without applying excessive contact forces has been a challenge for traditional rigid robot grippers. To solve this challenge, soft robotic grippers have been recently proposed for applying small forces and for conforming to complex 3D object shapes passively and easily. However, rigid grippers are still able to exert larger forces, necessary for picking heavy objects. Therefore, in this study, we propose a magnetically switchable soft suction gripper (diameter: 20 mm) to be able to apply both small and large forces. The suction gripper is in its soft state during approach and attachment while it is switched to its rigid state during picking. Such stiffness switching is enabled by filling the soft suction cup with a magnetorheological fluid (MR fluid), which is switched between low-viscosity (soft) and high-viscosity (rigid) states using a strong magnetic field. We characterized the gripper by measuring the force required to pull the gripper from a smooth glass surface. The force was up to 90% larger when the magnetic field was applied (7.1 N vs. 3.8 N). We also demonstrated picking of curved, rough, and wet 3D objects, and thin and delicate films. The proposed stiffness-switchable gripper can also carry heavy objects and still be delicate while handling fragile objects, which is very beneficial for future potential industrial part pick-and-place applications.

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Mechanics of a pressure-controlled adhesive membrane for soft robotic gripping on curved surfaces

Cited by 19 publications

References 41 publications

Versatile Soft Robot Gripper Enabled by Stiffness and Adhesion Tuning via Thermoplastic Composite

Versatile Soft Robot Gripper Enabled by Stiffness and Adhesion Tuning via Thermoplastic Composite

Gas‐Lubricated Vibration‐Based Adhesion for Robotics

Magnetically switchable soft suction grippers

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