Grasping Without Squeezing: Design and Modeling of Shear-Activated Grippers

Hawkes, Elliot W.; Jiang, Hao; Christensen, David L.; Han, Amy Kyungwon; Cutkosky, Mark R.

doi:10.1109/tro.2017.2776312

Cited by 70 publications

(52 citation statements)

References 31 publications

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“…As seen in the following sections, when testing fibrillar adhesives the parasitic stage rotations are not an issue and do not reduce the measured adhesive stress. The points on the corresponding limit curves match the results obtained empirically for particular loading directions in applications [22], [55], [57].…”

Section: A Flat Pdmssupporting

confidence: 77%

“…To investigate the effects of test method on the apparent limit surfaces of microstructured gecko-inspired adhesives, we begin by considering the measured performance of wedgelike controllable adhesives developed and used in [8], [22], [55], and shown in Fig. 4b.…”

Section: B Microwedge Adhesivesmentioning

confidence: 99%

“…For a less carefully aligned example, we created a "backwards" version of the flexible film gripper described in [22]. As seen in Fig.…”

Section: Correspondence With Applicationsmentioning

confidence: 99%

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Forcing the issue: testing gecko-inspired adhesives

Suresh

Hajj‐Ahmad

Hawkes

et al. 2021

J. R. Soc. Interface.

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Materials are traditionally tested either by imposing controlled displacements and measuring the corresponding forces, or by imposing controlled forces. The first of these approaches is more common because it is straightforward to control the displacements of a stiff apparatus and, if the material suddenly fails, little energy is released. However, when testing gecko-inspired adhesives, an applied force paradigm is closer to how the adhesives are loaded in practice. Moreover, we demonstrate that the controlled displacement paradigm can lead to artefacts in the assumed behaviour unless the imposed loading trajectory precisely matches the deflections that would occur in applications. We present the design of a controlled-force system and protocol for testing directional gecko-inspired adhesives and show that results obtained with it are in some cases substantially different from those with controlled-displacement testing. An advantage of the controlled-force testing approach is that it allows accurate generation of adhesive limit curves without prior knowledge of the expected behaviour of the material or the loading details associated with practical applications.

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Section: A Flat Pdmssupporting

confidence: 77%

Section: B Microwedge Adhesivesmentioning

confidence: 99%

See 1 more Smart Citation

Forcing the issue: testing gecko-inspired adhesives

Suresh

Hajj‐Ahmad

Hawkes

et al. 2021

J. R. Soc. Interface.

Self Cite

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show abstract

“…The inner surface of each phalanx is covered with spines, which most effectively provide attachment when also loaded in shear [16]. As such, the actuated contact forces should have a lateral component directed along the finger, similar to grippers that use directional adhesion [31,32].…”

Section: Spined Fingers 31 Prismatic Phalanxmentioning

confidence: 99%

SpinyHand: Contact Load Sharing for a Human-Scale Climbing Robot

Wang

Jiang

Huh

et al. 2019

Journal of Mechanisms and Robotics

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We present a hand specialized for climbing unstructured rocky surfaces. Articulated fingers achieve grasps commonly used by human climbers. The gripping surfaces are equipped with dense arrays of spines that engage with asperities on hard rough materials. A load-sharing transmission system divides the shear contact force among spine tiles on each phalanx to prevent premature spine slippage or grasp failure. Taking advantage of the hand’s kinematic and load-sharing properties, the wrench space of achievable forces and moments can be computed rapidly. Bench-top tests show agreement with the model, with average wrench space errors of 10–15%, despite the stochastic nature of spine/surface interaction. The model provides design guidelines and control strategy insights for the SpinyHand and can inform future work.

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“…26 Similarly, Hawkes et al presented a shear-activated gripper based on a gecko-inspired fibrillar material with adhesive characteristics for lifting soft, brittle, fragile, light, and even very heavy objects. 27 Besides, the OctArm inspired by elephant trunk can grasp a wide range of objects with a variety of sizes and payloads with its winding 28,29 ; however, it can't manipulate very small objects compared to its size.…”

Section: Introductionmentioning

confidence: 99%