HumanFT: A Human-like Fingertip Multimodal Visuo-Tactile Sensor

TL;DR

HumanFT, a multimodal visuotactile sensor that replicates the shape and functionality of a human fingertip, is proposed that can enhance humanoid robots' perception by capturing and interpreting multimodal tactile information.

Abstract

Tactile sensors play a crucial role in enabling robots to interact effectively and safely with objects in everyday tasks. In particular, visuotactile sensors have seen increasing usage in two and three-fingered grippers due to their high-quality feedback. However, a significant gap remains in the development of sensors suitable for humanoid robots, especially five-fingered dexterous hands. One reason is because of the challenges in designing and manufacturing sensors that are compact in size. In this paper, we propose HumanFT, a multimodal visuotactile sensor that replicates the shape and functionality of a human fingertip. To bridge the gap between human and robotic tactile sensing, our sensor features real-time force measurements, high-frequency vibration detection, and overtemperature alerts. To achieve this, we developed a suite of fabrication techniques for a new type of elastomer optimized for force propagation and temperature sensing. Besides, our sensor integrates circuits capable of sensing pressure and vibration. These capabilities have been validated through experiments. The proposed design is simple and cost-effective to fabricate. We believe HumanFT can enhance humanoid robots' perception by capturing and interpreting multimodal tactile information.

Figures (9)

• Figure 1: HumanFT: a visuotactile sensor with a shape similar to a human fingertip. It features multimodal sensing capability due to the integration of sensors within the elastomer.
• Figure 2: Exploded view of the visuotactile sensor assembly. The sensor comprises three main functional components: (1) a transparent elastomer with thermochromic coating, (2) an endoscopic camera, and (3) a PCB equipped with vibration and pressure sensors. This configuration enables multimodal sensing, allowing the detection of elastomer deformation, contact forces, and vibrations.
• Figure 3: Fabrication procedures for the elastomer and sensor assembly. (A) Create a mold using 3D printing, (B) fabricate the coating layer, (C) fill with PDMS and demold the cured elastomer, (D) create a second mold with a pushing slot, (E) transfer cured elastomer into the second mold, (F) crosslink the PCB by filling with PDMS, and demold by pushing out the sensor.
• Figure 4: Our experimental setups, for applying (A) external forces, and (B) mechanical vibration to HumanFT sensor.
• Figure 5: Experimental results of force and vibration characterization. (1) Our sensor's capability to characterize shear forces $F_x$, $F_y$, and normal force $F_z$ using $p_x$, $p_y$, and $p_z$ from the pressure sensors' outputs; (2) sensor's ability to detect mechanical vibrations during sliding motion.