Design of a Sensitive Balloon Sensor for Safe Human–Robot Interaction

As the safety of a human body is the main priority while interacting with robots, the field of tactile sensors has expanded for acquiring tactile information and ensuring safe human–robot interaction (HRI). Existing lightweight and thin tactile sensors exhibit high performance in detecting their surroundings. However, unexpected collisions caused by malfunctions or sudden external collisions can still cause injuries to rigid robots with thin tactile sensors. In this study, we present a sensitive balloon sensor for contact sensing and alleviating physical collisions over a large area of rigid robots. The balloon sensor is a pressure sensor composed of an inflatable body of low-density polyethylene (LDPE), and a highly sensitive and flexible strain sensor laminated onto it. The mechanical crack-based strain sensor with high sensitivity enables the detection of extremely small changes in the strain of the balloon. Adjusting the geometric parameters of the balloon allows for a large and easily customizable sensing area. The weight of the balloon sensor was approximately 2 g. The sensor is employed with a servo motor and detects a finger or a sheet of rolled paper gently touching it, without being damaged.

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A Pressure-Insensitive Self-Attachable Flexible Strain Sensor with Bioinspired Adhesive and Active CNT Layers

Sensors ◽

10.3390/s20236965 ◽

2020 ◽

Vol 20 (23) ◽

pp. 6965

Author(s):

Minho Seong ◽

Insol Hwang ◽

Joosung Lee ◽

Hoon Eui Jeong

Keyword(s):

Tensile Strain ◽

High Strain ◽

Strain Sensor ◽

Adhesive Layer ◽

High Sensitivity ◽

Gauge Factor ◽

Tactile Sensors ◽

Surface Attachment ◽

Tactile Stimuli ◽

Flexible Strain Sensor

Flexible tactile sensors are required to maintain conformal contact with target objects and to differentiate different tactile stimuli such as strain and pressure to achieve high sensing performance. However, many existing tactile sensors do not have the ability to distinguish strain from pressure. Moreover, because they lack intrinsic adhesion capability, they require additional adhesive tapes for surface attachment. Herein, we present a self-attachable, pressure-insensitive strain sensor that can firmly adhere to target objects and selectively perceive tensile strain with high sensitivity. The proposed strain sensor is mainly composed of a bioinspired micropillar adhesive layer and a selectively coated active carbon nanotube (CNT) layer. We show that the bioinspired adhesive layer enables strong self-attachment of the sensor to diverse planar and nonplanar surfaces with a maximum adhesion strength of 257 kPa, while the thin film configuration of the patterned CNT layer enables high strain sensitivity (gauge factor (GF) of 2.26) and pressure insensitivity.

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Soft magnetic skin for super-resolution tactile sensing with force self-decoupling

Science Robotics ◽

10.1126/scirobotics.abc8801 ◽

2021 ◽

Vol 6 (51) ◽

pp. eabc8801

Author(s):

Youcan Yan ◽

Zhe Hu ◽

Zhengbao Yang ◽

Wenzhen Yuan ◽

Chaoyang Song ◽

...

Keyword(s):

External Disturbance ◽

Super Resolution ◽

Tactile Sensor ◽

Human Robot Interaction ◽

Tactile Sensors ◽

Dexterous Manipulation ◽

Robot Interaction ◽

Flexible Film ◽

Challenging Tasks ◽

External Forces

Human skin can sense subtle changes of both normal and shear forces (i.e., self-decoupled) and perceive stimuli with finer resolution than the average spacing between mechanoreceptors (i.e., super-resolved). By contrast, existing tactile sensors for robotic applications are inferior, lacking accurate force decoupling and proper spatial resolution at the same time. Here, we present a soft tactile sensor with self-decoupling and super-resolution abilities by designing a sinusoidally magnetized flexible film (with the thickness ~0.5 millimeters), whose deformation can be detected by a Hall sensor according to the change of magnetic flux densities under external forces. The sensor can accurately measure the normal force and the shear force (demonstrated in one dimension) with a single unit and achieve a 60-fold super-resolved accuracy enhanced by deep learning. By mounting our sensor at the fingertip of a robotic gripper, we show that robots can accomplish challenging tasks such as stably grasping fragile objects under external disturbance and threading a needle via teleoperation. This research provides new insight into tactile sensor design and could be beneficial to various applications in robotics field, such as adaptive grasping, dexterous manipulation, and human-robot interaction.

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Flexible strain sensor based on embedded three-dimensional annular cracks with high mechanical robustness and high sensitivity

Applied Materials Today ◽

10.1016/j.apmt.2021.101247 ◽

2021 ◽

Vol 25 ◽

pp. 101247

Author(s):

Duorui Wang ◽

Xiangming Li ◽

Hongmiao Tian ◽

Xiaoliang Chen ◽

Bangbang Nie ◽

...

Keyword(s):

Three Dimensional ◽

Strain Sensor ◽

High Sensitivity ◽

Flexible Strain Sensor ◽

Annular Cracks

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High-sensitivity crack-based flexible strain sensor with dual hydrogen bond-assisted structure for monitoring tiny human motions and writing behavior

Organic Electronics ◽

10.1016/j.orgel.2020.105977 ◽

2021 ◽

Vol 88 ◽

pp. 105977

Author(s):

Caixia Liu ◽

Mengdi Li ◽

Baisheng Lu ◽

Ying Huang ◽

Yangyang Zhang ◽

...

Keyword(s):

Hydrogen Bond ◽

Strain Sensor ◽

High Sensitivity ◽

Flexible Strain Sensor ◽

Human Motions

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Towards natural handshakes for social robots: human-aware hand grasps using tactile sensors

Paladyn Journal of Behavioral Robotics ◽

10.1515/pjbr-2018-0017 ◽

2018 ◽

Vol 9 (1) ◽

pp. 221-234 ◽

Cited By ~ 2

Author(s):

João Avelino ◽

Tiago Paulino ◽

Carlos Cardoso ◽

Ricardo Nunes ◽

Plinio Moreno ◽

...

Keyword(s):

Human Subjects ◽

Tactile Feedback ◽

Human Robot Interaction ◽

Physical Interaction ◽

Tactile Sensors ◽

Cultural Backgrounds ◽

Robot Interaction ◽

Human Interactions ◽

Hand Grip ◽

Fundamental Part

Abstract Handshaking is a fundamental part of human physical interaction that is transversal to various cultural backgrounds. It is also a very challenging task in the field of Physical Human-Robot Interaction (pHRI), requiring compliant force control in order to plan the arm’s motion and for a confident, but at the same time pleasant grasp of the human user’s hand. In this paper,we focus on the study of the hand grip strength for comfortable handshakes and perform three sets of physical interaction experiments between twenty human subjects in the first experiment, thirty-five human subjects in the second one, and thirty-eight human subjects in the third one. Tests are made with a social robot whose hands are instrumented with tactile sensors that provide skin-like sensation. From these experiments, we: (i) learn the preferred grip closure according to each user group; (ii) analyze the tactile feedback provided by the sensors for each closure; (iii) develop and evaluate the hand grip controller based on previous data. In addition to the robot-human interactions, we also learn about the robot executed handshake interactions with inanimate objects, in order to detect if it is shaking hands with a human or an inanimate object. This work adds physical human-robot interaction to the repertory of social skills of our robot, fulfilling a demand previously identified by many users of the robot.

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Bioinspired design of flexible strain sensor with high performance based on gradient filler distributions

Composites Science and Technology ◽

10.1016/j.compscitech.2020.108319 ◽

2020 ◽

Vol 200 ◽

pp. 108319

Author(s):

Rong Zhang ◽

Siqi Li ◽

Cheng Ying ◽

Zikang Hu ◽

An Lv ◽

...

Keyword(s):

High Performance ◽

Strain Sensor ◽

Bioinspired Design ◽

Flexible Strain Sensor

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High performance flexible strain sensor based on self-locked overlapping graphene sheets

Nanoscale ◽

10.1039/c6nr07620c ◽

2016 ◽

Vol 8 (48) ◽

pp. 20090-20095 ◽

Cited By ~ 67

Author(s):

Dan-Yang Wang ◽

Lu-Qi Tao ◽

Ying Liu ◽

Tian-Yu Zhang ◽

Yu Pang ◽

...

Keyword(s):

High Performance ◽

Strain Sensor ◽

Graphene Sheets ◽

Flexible Strain Sensor

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Effect of Metal Thickness on the Sensitivity of Crack-Based Sensors

Sensors ◽

10.3390/s18092872 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2872 ◽

Cited By ~ 10

Author(s):

Eunhan Lee ◽

Taewi Kim ◽

Heeseong Suh ◽

Minho Kim ◽

Peter Pikhitsa ◽

...

Keyword(s):

American Sign Language ◽

High Performance ◽

Metal Layer ◽

High Sensitivity ◽

Human Motion ◽

Motion Detector ◽

Metal Thickness ◽

Mechanical Crack ◽

Pet Film ◽

The Relationship

Among many attempts to make a decent human motion detector in various engineering fields, a mechanical crack-based sensor that deliberately generates and uses nano-scale cracks on a metal deposited thin film is gaining attention for its high sensitivity. While the metal layer of the sensor must be responsible for its high performance, its effects have not received much academic interest. In this paper, we studied the relationship between the thickness of the metal layer and the characteristics of the sensor by depositing a few nanometers of chromium (Cr) and gold (Au) on the PET film. We found that the sensitivity of the crack sensor improves/increases under the following conditions: (1) when Au is thin and Cr is thick; and (2) when the ratio of Au is lower than that of Cr, which also increases the transmittance of the sensor, along with its sensitivity. As we only need a small amount of Au to achieve high sensitivity of the sensor, we have suggested more efficient and economical fabrication methods. With this crack-based sensor, we were able to successfully detect finger motions and to distinguish various signs of American Sign Language (ASL).

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