Research On Multi-functional Detection System Of Tactile Signal Based On PVDF Film

Some physical characteristics on the surface of the object(such as hardness, appearance, texture, material qualitative, cold and hot conditions, etc.) can be obtained from tactile signal. With the development of bionics, tactile sensors are widely used in bionic robot, medical equipment, sports training, ergonomics and so on. It becomes a hot spot that detecting multiple physical quantities with a multi-functional tactile sensor at the same time. Besides, the material and structure of the sensor itself, signal detection system is the important guarantee of the sensor performance the material and structure of the sensor itself. In this paper, multi-functional tactile signal detection system is proposed for detecting contact signal, slip signal and thermal signal based on piezoelectric thin film. It shows that stability of the system can meet the design requirements. According to the measurement results can get that it can obtain the stress and temperature changes signal of tactile sensor surface.In this paper, a convex point type fingerprint sensor was designed based on the bionics. In the sensor, PVDF film as the sensing element. It is flexibility, mechanical strength and corrosion resistance to impact, easy to processing. The rubber layer is the substrate for its delivering tactile and slip sensation vibration information. Copper foil is regarded as the convex point type structure which is strong flexibility and good electrical conductivity. The multi-function tactile sensor obtained the electrical signal when contacts the objects. Then the signal was passed to the PC via a serial port communication through the hardware circuit. The function of signal conditioning circuit is amplified, filtering, and uplifting. MCU is responsible for the signal of the A/D conversion. Then Lab VIEW software was used for further filtering, signal types and display waveform parameters. In addition, the ANSYS software was used to simulate the piezoelectricity and pyroelectricity of the sensor.Through analysis the contrast experiment of planar sensor, ordinary ring type fingerprint sensor and the new type of fingerprint sensor, it is concluded that the multi-functional sensor sensitivity is 2.067 times of planar sensor and is 1.156 times that of ordinary fingerprint sensor. In the system overall performance test, Lab VIEW program can successfully identify the types of sensor signals(contact, slip and temperature) and signal amplitude which show that the system has the versatility. In addition, in the identifying objects kinds of experiments, 20 times repeated trials, the accuracy is as high as 94%. The results showed that the multi-functional sensor is high sensitivity with good recovery. The whole system has a good stability condition. In temperature sensation function test, it verified the effectiveness of the system working temperature range. It also verified materials thermal conductivity can be distinguished based on the system detecting thermal sensation. AYSYS simulation software to verify the sensor of piezoelectric and pyroelectric properties. All above, it can provide a new technical support for the intelligent robot research and development and the development of artificial limbs.