3-D-Curved Iontronic Tactile Sensor and Denoising Method for Physical Human–Robot Interactions

Tactile information is essential for safe physical interactions between humans and robots. However, for all kinds of tactile sensing principles, it is still challenging to monitor contact status during physical human–robot interactions (pHRIs) on 3-D irregular surfaces due to complex tactile sensor design and signal denoising. This study developed a robotic tactile sensing system by introducing the iontronic electric double-layer capacitor (EDLC) supercapacitive principle, covering a large area ( $191\times191$ mm), and ensuring a dense spatial resolution by using 1024 sensing units. A special grounding strategy and a spatio-temporal (S-T) digital filter significantly reduced the crosstalk interference resulting from low ionic mobility and lateral migration. Additionally, based on surface flattening technology, a 3-D-curved tactile sensor is presented for tactile sensing of a humanoid lower limb's foot. Finally, response tests based on human actions were performed by the two kinds of robots. Results showed that the system could rapidly capture the entire dynamic process of pHRI actions and distinguish actions in real-time. This study enables the possibility of tactile sensing with whole-body coverage, rapid responses, and tactile-based robotic intelligence.