Embedding Soft Material Channels for Tactile Sensing of Complex Surfaces—Mathematical Modeling

Currently most of tactile array technologies is difficult to cope with three dimensional complex surfaces and there is an urgent need to develop tactile sensors that can provide a high-density integrated array on a surface of arbitrary shape. Our laboratory has been working on the development of a novel tactile sensing technique to solve this challenge, by “Embedding Soft material into Structure ENabling Tactile sensing” of complex surfaces (ESSENT). This method creates sub-millimeter multiple channels filled with low compressibility elastic material. Tactile information is obtained by measuring the micro deformation of the soft material via projecting light to the material channel and measuring light reflection. However, the relationship between light reflection and soft material deformation is a complex function related to the geometry of reflective surface, elasticity of the soft channel and lighting conditions. To gain fundamental understanding of this new tactile sensing principle, we developed a mathematical model which is able to predict the precise deformation of the reflective surface of a soft material and provide the theoretical prediction of sensing sensitivity with respect to the lighting condition and the magnitude of the applied force. We demonstrated that the shape of soft material channel, the shape of reflective surface, as well as the location of light resource have significant influence on the sensor behavior.