A Capacitive and Piezoresistive Hybrid Sensor for Long‐Distance Proximity and Wide‐Range Force Detection in Human–Robot Collaboration

Abstract

Safety is a core concern in human–robot collaboration (HRC), which highly relies on multi‐information collected from its environment by various sensors. Current passive solution is to isolate the robot from human by fences or cages, which is invalid for a real collaborative robot, especially for the domestic and rehabilitation robots. Herein, a capacitive and piezoresistive hybrid sensor for long‐distance proximity and wide‐range force detection in HRC is reported. The sensor composes a pair of interdigital copper foil worked as the electrode for both coplanar capacitors and resistors, while a carbon black in polymer matrix works as the piezoresistive material. As‐prepared hybrid sensor can detect the object approaching as far as 100 mm, while a contact force covers from 0 to 450 N. The maximum sensitivity is 0.65 mm−1 for object proximity, and 17.73 N−1 for contact force. Significantly, the proposed hybrid sensor is feasible and scalable integration for the electronic‐skins (e‐skins) with superior stability, mechanical flexibility and deformability, which can withstand large compression, bending and torsion in applications. Finally, the e‐skins are used for safety control in two types of commercial robots, which exhibits the long‐distance proximity and large‐range force detection capabilities, illustrating its potential usage in complex, precise, and safe requirement conditions.

Dual‐Function Tactile Sensor with Linear Pressure and Temperature Perception at Low Degree of Coupling

“…Then, the carbon black/PDMS mixture is prepared via the same method reported by our group before. [ 25 ] The mixtures with carbon black concentrations of 20% and 3.5% are sprayed on the pyramid structure sequentially, forming the two‐layer conductive film (Figure S2b, Supporting Information). It can be seen that the pyramid structure is still very clear (Figure S2b, Supporting Information).…”

“…With these perceptual information, the robots can operate in multiple tasks and an unknown complex environment with the features of feasibility, accuracy, and real time. [ 25 ] Meanwhile, it can effectively reduce the risk of injury to people, external objects, and robot themselves. Among these information, the contact pressure and temperature are highly important for the robot operation smooth with environment.…”

“…[26][27][28] However, the e-skins are usually single function for force, pressure, temperature, humidity, and approximate sensing, which cannot fulfill the requirements for the robot operation. [25,27,28] Many attempts have been done to develop multimodal perception e-skins, [29][30][31][32][33][34][35][36] which can be divided into three parts. First, it is to integrate multiple sensors in a side-by-side or stacked manner.…”

Perspective of Proximity Sensors on Robots Using Cross-Thought

“…In all, this eskin is of high Stability and practicality. This sensor now has been used on 2 types of commercial robots until now [4].…”

“…A presumed direction of development is that in the future, there will be more and more hybrid applications of proximity sensors, such as the mixing of capacitive and pressure sensors, ultrasonic and pressure sensors, inductive proximity sensors and capacitive sensors, etc. [4,16,17]. For example, by mixing mentioned electronic detection-based proximity sensors and ultrasonic sensors, it is possible to make the detection of both long-range and close-range objects convenient and reliable.…”