Laminated Piezoelectret Film As Electronic Skin For Texture Recognition

Electronic skin is a kind of sensor that can simulate or even surpass the function of human skin.Through the design of material and structure,it can realize the reliable response of many external stimulation signals,such as stress,temperature,magnetic field and gas.It is an important human-computer interaction medium in the application of intelligent robots and artificial limbs in the future.Judging texture by touch perception is one of the most basic and important functions of electronic skin to simulate human skin.Among them,finger skin,as the most sensitive tactile area of the human body,can transform the static stress and dynamic vibration generated when it contacts and presses with the object surface and sliding friction into a series of bioelectrical signals through the collaborative work of four kinds of mechanical stimulation receptors on the skin,and transmit them to the big brain for the analysis and judgment of the object surface texture.In order to simulate this function,traditional mechanical sensing materials,such as rigid piezoelectric ceramics and piezoresistive rubber,are limited in practical application due to their poor adhesion or poor response to high-frequency vibration.Therefore,the design of a flexible tactile sensor which can realize both static pressure sensing and fast vibration response is of great significance for the design and development of electronic skin with texture recognition ability.In order to solve the above problems,the piezoelectric electret composite film,which is light,thin and flexible,is introduced into the electronic skin as a tactile sensor in this paper.It can fit on the curved surface and endow it with tactile sensing ability.The film device not only has good quasi-static pressure response,but also has a stable,consistent and highly sensitive dynamic force response.Combined with signal processing,the electronic skin can perceive and distinguish a variety of objects with different surface roughness and texture.This research provides a feasible way for the development of a more intelligent human-computer interface.The main contents and significance of this paper are as follows:(1)The electronic skin of piezoelectric electret composite film based on electrostatic assembly was designed.The sandwich structure without holes has excellent transmissivity and suppresses the loss of electret charge caused by humidity.After 30 days in 80%humidity environment,its piezoelectric properties remain stable.The flexible piezoelectric electret composite film has high sensitivity(8.75 m V/?m)and dynamic sensing ability.It can recognize the surface texture with a height of R_aof 0.8?m and an interval of 500?m.(2)The tactile test system of piezoelectric electret composite film electronic skin is built to realize the effective collection of the surface texture signal from the electronic skin.The signal analysis means,such as smooth curve,unified baseline,signal extraction are used to preprocess,and then the peak mean value,Fourier transform and other methods are used to extract and transform the surface texture information.The texture height,interval,and the texture information are studied The influence of friction pressure,sliding speed and other parameters on tactile signal.(3)It is shown that the piezoelectric electret composite film electronic skin can sense a variety of objects with different surface textures,and the surface texture information database can be established according to the obtained tactile signals,so that the materials can be judged by touch analysis,and the unknown objects can be recognized,which can improve the interaction ability of industrial processing,intelligent robot and medical penetration detection equipment.