1,438 research outputs found
A bistable soft gripper with mechanically embedded sensing and actuation for fast closed-loop grasping
Soft robotic grippers are shown to be high effective for grasping
unstructured objects with simple sensing and control strategies. However, they
are still limited by their speed, sensing capabilities and actuation mechanism.
Hence, their usage have been restricted in highly dynamic grasping tasks. This
paper presents a soft robotic gripper with tunable bistable properties for
sensor-less dynamic grasping. The bistable mechanism allows us to store
arbitrarily large strain energy in the soft system which is then released upon
contact. The mechanism also provides flexibility on the type of actuation
mechanism as the grasping and sensing phase is completely passive. Theoretical
background behind the mechanism is presented with finite element analysis to
provide insights into design parameters. Finally, we experimentally demonstrate
sensor-less dynamic grasping of an unknown object within 0.02 seconds,
including the time to sense and actuate
Actuation Technologies for Soft Robot Grippers and Manipulators: A Review
Purpose of Review The new paradigm of soft robotics has been widely developed in the international robotics community. These
robots being soft can be used in applications where delicate yet effective interaction is necessary. Soft grippers and manipulators
are important, and their actuation is a fundamental area of study. The main purpose of this work is to provide readers with fast
references to actuation technologies for soft robotic grippers in relation to their intended application.
Recent Findings The authors have surveyed recent findings on actuation technologies for soft grippers. They presented six major
kinds of technologies which are either used independently for actuation or in combination, e.g., pneumatic actuation combined
with electro-adhesion, for certain applications.
Summary A review on the latest actuation technologies for soft grippers and manipulators is presented. Readers will get a guide
on the various methods of technology utilization based on the application
Advances in soft grasping in agriculture
Agricultural robotics and automation are facing some challenges rooted in the
high variability 9 of products, task complexity, crop quality requirement, and
dense vegetation. Such a set of 10 challenges demands a more versatile and safe
robotic system. Soft robotics is a young yet 11 promising field of research
aimed to enhance these aspects of current rigid robots which 12 makes it a good
candidate solution for that challenge. In general, it aimed to provide robots
13 and machines with adaptive locomotion (Ansari et al., 2015), safe and
adaptive manipulation 14 (Arleo et al., 2020) and versatile grasping (Langowski
et al., 2020). But in agriculture, soft 15 robots have been mainly used in
harvesting tasks and more specifically in grasping. In this 16 chapter, we
review a candidate group of soft grippers that were used for handling and 17
harvesting crops regarding agricultural challenges i.e. safety in handling and
adaptability to 18 the high variation of crops. The review is aimed to show why
and to what extent soft grippers 19 have been successful in handling
agricultural tasks. The analysis carried out on the results 20 provides future
directions for the systematic design of soft robots in agricultural tasks.Comment: Chapter 12 of the book entitled "Advances in agri-food robotics
非線形弾性要素による内部力補償に基づく無段階変位–力変換機構の創生 ― 微小操作力で強大な磁気力・把持力・制動力・張力を制御可能とするロボット要素 ―
Tohoku University博士(情報科学)thesi
Design and analysis of a variable-stiffness robotic gripper
This paper presents the design and analysis of a novel variable-stiffness robotic gripper, the RobInLab VS gripper. The purpose is to have a gripper that is strong and reliable as rigid grippers but adaptable as soft grippers. This is achieved by designing modular fingers that combine a jamming material core with an external structure, made with rigid and flexible materials. This allows the finger to softly adapt to object shapes when the capsule is not active, but becomes rigid when air suction is applied. A three-finger gripper prototype was built using this approach. Its validity and performance are evaluated using five experimental benchmark tests implemented exclusively to measure variable-stiffness grippers. To complete the analysis, our gripper is compared with an alternative gripper built by following a relevant state-of-the-art design. Our results suggest that our solution significantly outperforms previous approaches using similar variable stiffness designs, with a significantly higher grasping force, combining a good shape adaptability with a simpler and more robust design.This paper describes research conducted at UJI Robotic Intelligence Laboratory. Support for this laboratory is provided in part by Ministerio de Ciencia e Innnovación (DPI2015-69041-R and DPI2017-89910-R), by Universitat Jaume I (UJI-B2018-74), and by Generalitat Valenciana (PROMETEO/2020/034)
A Bioinspired Bidirectional Stiffening Soft Actuator for Multimodal, Compliant, and Robust Grasping
The stiffness modulation mechanism for soft robotics has gained considerable
attention to improve deformability, controllability, and stability. However,
for the existing stiffness soft actuator, high lateral stiffness and a wide
range of bending stiffness are hard to be provided at the same time. This paper
presents a bioinspired bidirectional stiffening soft actuator (BISA) combining
the air-tendon hybrid actuation (ATA) and a bone-like structure (BLS). The ATA
is the main actuation of the BISA, and the bending stiffness can be modulated
with a maximum stiffness of about 0.7 N/mm and a maximum magnification of 3
times when the bending angle is 45 deg. Inspired by the morphological structure
of the phalanx, the lateral stiffness can be modulated by changing the pulling
force of the BLS. The lateral stiffness can be modulated by changing the
pulling force to it. The actuator with BLSs can improve the lateral stiffness
about 3.9 times compared to the one without BLSs. The maximum lateral stiffness
can reach 0.46 N/mm. And the lateral stiffness can be modulated decoupling
about 1.3 times (e.g., from 0.35 N/mm to 0.46 when the bending angle is 45
deg). The test results show the influence of the rigid structures on bending is
small with about 1.5 mm maximum position errors of the distal point of actuator
bending in different pulling forces. The advantages brought by the proposed
method enable a soft four-finger gripper to operate in three modes: normal
grasping, inverse grasping, and horizontal lifting. The performance of this
gripper is further characterized and versatile grasping on various objects is
conducted, proving the robust performance and potential application of the
proposed design method
Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening
Realizing high-performance soft robotic grippers is challenging because of
the inherent limitations of the soft actuators and artificial muscles that
drive them, including low force output, small actuation range, and poor
compactness. Despite advances in this area, realizing compact soft grippers
with high dexterity and force output is still challenging. This paper explores
twisted string actuators (TSAs) to drive a soft robotic gripper. TSAs have been
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. Tunable stiffness was implemented in the fingers with antagonistic TSAs.
The fingers' bending angles, actuation speed, blocked force output, and
stiffness tuning were experimentally characterized. The gripper achieved a
score of 6 on the Kapandji test and recreated 31 of the 33 grasps of the Feix
GRASP taxonomy. It exhibited a maximum grasping force of 72 N, which was almost
13 times its own weight. A comparison study revealed that the proposed gripper
exhibited equivalent or superior performance compared to other similar soft
grippers.Comment: 19 pages, 15 figure
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