Centrosymmetric‐ and Axisymmetric‐Patterned Flexible Tactile Sensor for Roughness and Slip Intelligent Recognition

Abstract

Next‐generation robots are being designed to function autonomously in complex and unstructured environments. In particular, based on the real‐time measurement and differentiation of normal pressure and shear force, robots can be equipped with the capabilities of damage‐free grasp within minimum force limits, as well as dexterous operation through surface roughness and slip information. Herein, a flexible tactile sensor with a small cylinder protrusion and four arc‐shaped protrusions is developed. Due to its center symmetry and axisymmetry characteristics, the normal pressure and shear force can be decoupled from the complex stress without any interference from torsion. The flexible tactile sensor exhibits good linearity and superior cycling stability and is capable of determining the magnitude and direction of the applied force accurately. The flexible tactile sensor is comfortable to wear, and it is integrated onto the manipulator to realize various delicate and dexterous tasks, such as pressure detection, interaction with fragile objects, and roughness identification. Moreover, intelligent recognition of the sliding and stationary states can be achieved by decoding signals of sliding friction and static friction from the feedback information, leading to real time and precise adjustment of the grasping state of the manipulator.

Journey from human hands to robot hands: biological inspiration of anthropomorphic robotic manipulators

“…While the inspiration and physical properties of various projects are aligned, table 3 highlights distinctly different transduction mechanisms, materials, and components. The majority of soft-type sensors commonly detect changes in electrical signals, such as alterations in resistance, capacitance, or electrical charge in response to mechanical deformation [87,88,96]. These sensors can be seamlessly embedded onto elastomers in compact sizes, facilitating attachment to surfaces with flexible and stretchable features.…”

Recent Progress of Tactile and Force Sensors for Human–Machine Interaction

“…Therefore, a magnetic multi-dimensional tactile sensor was developed, where the normal and shear forces are naturally decoupled [ 72 ], as shown in Figure 4 e. However, this design is sensitive to the magnetic field interference, and the hall sensor chip used in this design increases the device thickness. A three-dimensional resistive tactile sensor with five bumps responding to forces in five perpendicular directions [ 118 ] and a multi-directional flexible tactile sensor for pressure, shear forces, and strains decoupled sensing were proposed [ 119 ], where the output sensing signals in different directions are independent of one another, as shown in Figure 4 f. Currently, multi-dimensional tactile sensors are required to be thinner and more flexible to be applied to electronic skin and HMI applications.…”

Pressure Sensors Combining Porous Electrodes and Electrospun Nanofiber-Based Ionic Membranes

“…Its detection principle is that when pressure is applied to the sensor (plate deformation), the dielectric layer is squeezed, resulting in a change in the distance between the two plates of the capacitive sensor and thus changing the system capacitance. In terms of human-body pressure monitoring, the typical human systolic blood pressure is between 13 and 26 kPa; on the other hand, the pressure of human finger pressing and object manipulation is above 10 kPa, and the resolution reaches below 100 Pa. , In addition, robot operation, high-speed fluid pressure testing, and other applications all need to achieve high sensitivity and high-pressure resolution under a pressure of more than 100 kPa. ,, Therefore, high sensitivity and a wide measuring range are important indexes of pressure sensor evaluation. − …”

“…In terms of human-body pressure monitoring, the typical human systolic blood pressure is between 13 and 26 kPa; on the other hand, the pressure of human finger pressing and object manipulation is above 10 kPa, and the resolution reaches below 100 Pa. 17,18 In addition, robot operation, high-speed fluid pressure testing, and other applications all need to achieve high sensitivity and high-pressure resolution under a pressure of more than 100 kPa. 5,19,20 Therefore, high sensitivity and a wide measuring range are important indexes of pressure sensor evaluation. 21−24 A great deal of research has been carried out for the sake of improving the sensitivity and measurement range of the sensor to achieve a more significant performance of the pressure sensor.…”