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SATac: A Thermoluminescence Enabled Tactile Sensor for Concurrent Perception of Temperature, Pressure, and Shear

Ziwu Song, Ran Yu, Xuan Zhang, Kit Wa Sou, Shilong Mu, Dengfeng Peng, Xiao-Ping Zhang, Wenbo Ding

TL;DR

SATac introduces a thermoluminescence-based tactile sensor that can concurrently sense temperature, pressure, and shear using a SA film and a dual-light field. It uses laser-cut, black-filled SA holes in silicone to enable clear temperature mapping, while Voronoi-area changes and centroid displacements extract pressure and shear from marker motion. Empirical results show a temperature response from 50 to 180 °C with good repeatability, and linear relationships between brightness and both applied pressure and shear. The approach provides high-resolution, multimodal tactile perception in a vision-based framework and suggests future work to broaden temperature range via SA doping.

Abstract

Most vision-based tactile sensors use elastomer deformation to infer tactile information, which can not sense some modalities, like temperature. As an important part of human tactile perception, temperature sensing can help robots better interact with the environment. In this work, we propose a novel multimodal vision-based tactile sensor, SATac, which can simultaneously perceive information of temperature, pressure, and shear. SATac utilizes thermoluminescence of strontium aluminate (SA) to sense a wide range of temperatures with exceptional resolution. Additionally, the pressure and shear can also be perceived by analyzing Voronoi diagram. A series of experiments are conducted to verify the performance of our proposed sensor. We also discuss the possible application scenarios and demonstrate how SATac could benefit robot perception capabilities.

SATac: A Thermoluminescence Enabled Tactile Sensor for Concurrent Perception of Temperature, Pressure, and Shear

TL;DR

SATac introduces a thermoluminescence-based tactile sensor that can concurrently sense temperature, pressure, and shear using a SA film and a dual-light field. It uses laser-cut, black-filled SA holes in silicone to enable clear temperature mapping, while Voronoi-area changes and centroid displacements extract pressure and shear from marker motion. Empirical results show a temperature response from 50 to 180 °C with good repeatability, and linear relationships between brightness and both applied pressure and shear. The approach provides high-resolution, multimodal tactile perception in a vision-based framework and suggests future work to broaden temperature range via SA doping.

Abstract

Most vision-based tactile sensors use elastomer deformation to infer tactile information, which can not sense some modalities, like temperature. As an important part of human tactile perception, temperature sensing can help robots better interact with the environment. In this work, we propose a novel multimodal vision-based tactile sensor, SATac, which can simultaneously perceive information of temperature, pressure, and shear. SATac utilizes thermoluminescence of strontium aluminate (SA) to sense a wide range of temperatures with exceptional resolution. Additionally, the pressure and shear can also be perceived by analyzing Voronoi diagram. A series of experiments are conducted to verify the performance of our proposed sensor. We also discuss the possible application scenarios and demonstrate how SATac could benefit robot perception capabilities.
Paper Structure (15 sections, 7 figures, 1 table)

This paper contains 15 sections, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. Sensor Design and Fabrication
  3. SA Material
  4. SA Film
  5. Dual-light Field
  6. Overall Sensor Architecture
  7. Feature Extraction
  8. Temperature
  9. Pressure and Shear
  10. Experiments
  11. Characterization
  12. Temperature
  13. Pressure and Shear
  14. Application
  15. Discussions and Conclusion

Figures (7)

  • Figure 1: (a) SATac, the touched object, and the robot arm equipped with SATac exploring the environment. (b) The raw image captured by the camera inside SATac. (c) The 3 modalities including temperature, pressure, and shear decoupled from the raw image.
  • Figure 2: Design and fabrication process of SATac: (a) The exploded view of SATac. (b) The four steps to fabricate SA film: step 1, mix the heat-resistant silicone with powdered SA to make the SA-Silicone; step 2, fabricate Raw film 1 with knife coating; step 3, fabricate Raw film 2 using laser cutting on Raw film 1; step 4, fabricate the SA film with knife coating filling the black silicone in holds.
  • Figure 3: The complete working flow of inferring temperature (Image 5), pressure (Image 8), and shear (Image 9) from the raw image (Image 1). Temperature information is extracted with methods including guided filtering, inpainting, and remapping. Marker contouring detection and Voronoi diagram algorithm are used for processing pressure and shear, which are calculated by area change rate and marker displacement respectively.
  • Figure 4: Characterization Experiment of Temperature Sensing. (a) Experimental setup for characterizing the performance of SATac in temperature sensing. (b) Experimental data for SATac's contact temperature when in contact with objects ranging from 50°C to 200°C. (c) Performance of SATac under different temperature conditions.
  • Figure 5: Characterization experiment of SATac pressure and shear sensing. (a) Experimental setup. (b) Experimental data for applying positive pressures of 2 N, 4 N, 6 N, and 8 N at pressing positions P1, P6, P11, P16, and P21. (c) Experimental data for applying shear of 0.2 N, 0.4 N, 0.6 N, 0.8 N, and 1.0 N. (d) The linear relationship between the brightness and the applied pressure. (e) The linear relationship between the marker displacement and the applied shear force.
  • ...and 2 more figures