🤖 AI Summary
This work proposes a novel ultrathin, soft optical tactile sensor that overcomes the limitations of conventional designs, which are typically bulky, rigid, and sensitive to optical misalignment due to complex light paths. By leveraging deformation-induced speckle pattern changes in a compliant silicone medium under applied force, the sensor enables high-precision force estimation and texture recognition through machine learning, without requiring lenses or high-end cameras. The minimalist architecture—comprising only a soft speckle-generating elastomer and a simple imaging setup—significantly enhances mechanical compliance and compactness, making it well-suited for integration into soft robotics and wearable devices. Experimental results demonstrate a low root-mean-square force estimation error of 40 mN and a 93.33% accuracy in classifying nine distinct textures, including mahjong tiles.
📝 Abstract
Tactile sensing is crucial in robotics and wearable devices for safe perception and interaction with the environment. Optical tactile sensors have emerged as promising solutions, as they are immune to electromagnetic interference and have high spatial resolution. However, existing optical approaches, particularly vision-based tactile sensors, rely on complex optical assemblies that involve lenses and cameras, resulting in bulky, rigid, and alignment-sensitive designs. In this study, we present a thin, compact, and soft optical tactile sensor featuring an alignment-free configuration. The soft optical sensor operates by capturing deformation-induced changes in speckle patterns generated within a soft silicone material, thereby enabling precise force measurements and texture recognition via machine learning. The experimental results show a root-mean-square error of 40 mN in the force measurement and a classification accuracy of 93.33% over nine classes of textured surfaces, including Mahjong tiles. The proposed speckle-based approach provides a compact, easily fabricated, and mechanically compliant platform that bridges optical sensing with flexible shape-adaptive architectures, thereby demonstrating its potential as a novel tactile-sensing paradigm for soft robotics and wearable haptic interfaces.