The Study Of Tactile Mechanisms Based On The Principles Of Neurons

In precision process, intelligent robot end effector or dexterous hand haptic perception is very important. The main perception form of tactile including proximity, slip, temperature, vibration, texture, shape etc, Which reflecting the contact state between the mechanical fingers and the target and the information characteristics of goal. Tactile sensor, the key part of the development of intelligent robot, is the media of a robot direct effect between the external environment and target object. When the robot is more and more widely used in medical, aerospace, military, marine and service field, very programming environment proposed higher requirements for tactile sensor.Paper works are as follows:(1) Based on the material properties of PVDF piezoelectric film, prepared flexible PVDF sensor sensitive element, and tested performance of the sensitive element with tactile and slip. In order to prepare flexible tactile sensor, silicone fingers model finger with soft characteristics is prepared. Different structure of finger epidermal is analysis in finite element, and the finger skin structure which sensitivity of transmission signal is selected.(2) Using flexible PVDF material as slide sensor sensitive element. The sensitive cell array is constructed based on PVDF piezoelectric theory. And the friction coefficient H is calculated from the output signal of the array sensitive element. According to variation features of the different friction coefficient μ, slip state between the fingers and the target is determined. In order to fully validate the feasibility of the scheme, the experimental platform device is prepared to detect sample of slip sensor.(3) Using PVDF thermoelectric effect to design temperature tactile sensor. When PVDF sensor detects the temperature’s change, the piezoelectric signal and thermoelectric signal exist at the same time. Using the characteristic of thermoelectric signal changes slowly or sensitive unit layout, frequency filter can separate the thermoelectric signals.(4) Based on the theory of the small deflection of thin plates, hardness sensor is designed. The elasticity coefficient of the object is considered to be of the characteristics of soft. Hardness sensor pressing target and the target can become deformed. According to the deformation of hardness sensor, the size of the load applied on the target is derived. The elastic coefficient of the target can determine the hardness.Through the above research, the following research results are obtained:(1) The sample of tactile sensor with the structure of PVDF piezoelectric thin film sensing unit is developed which provide touch slip and thermal function.(2) Three-dimensional force component is calculated from output signals of array type PVDF sensitive unit which can calculate the change of friction coefficient. According to slipping characteristics, the state of the slip between the fingers and the object is determined. It can overcome the defects that PVDF can only detect the dynamical load and can not exact detect the static. The experimental results show that slide tactile sensor reliably detect the slipping state between the fingers and the object.(3) The experimental results show that the thermal response of the temperature sensor can be separated from the piezoelectric signal by the frequency filtering and the layout of the piezoelectric film sensitive unit.(4) Through theoretical deduction, the relationship between the circular thin plate strain of hardness sensor and the load applied to the object is obtained. And the relationship between the thin circular plate strain and the hardness of target is obtained too. The feasibility of the hardness sensor is further confirmed through the finite element simulation.