Research On Flexible Tactile Sensor For Prosthesis Hand

With the national population of the disable increasing,their problem of the losing of ability to work and live normally could not be neglected.For now the best way to solve this problem is to create a prosthesis to replace its counterpart.The new generation of the smart prosthesis has surpassed the old one with the ability to communicate with human from both ways.And the tactile sensor is the key to support this capacity and the most important method to collected information from the environment.Based on this solid demand and supported by National Basic Research Program of China(973 project,NO.2011CB013303),this dissertation presents a new type of flexible tactile sensor array.This sensor employs the composite sub-micro fibers as the sensitive parts and forms one sensing element by depositing aligned fibers perpendicular to two parallel electrodes.The sensor arrays are in parallel on both sides of FPCB and orthogonal to each other.The main contents of the dissertation offers the following:In Chapter 1,the background and significance of this research were introduced,along with the development trend,the working principles and the application on prothesis of artificial tactile sensor.The sensor based on fiber material and their fabrication method were also introduced.At last part,the research contents of this dissertation were proposed.In Chapter 2,the theories of percolation and piezoresistivity were summarized.A theory based on quantum tunneling theory for the piezoresistivity of composite aligned fiber with CNT as fillers was proposed.Then the concept of' electrospinning and the devices of controllable methods were introduced and an auto electrospinning equipment was built based on these methods.And the calculation method for percolation threshold of polymer/CNT composite in fiber structure was deduced and experiments were carried out to test it.Then the parameters for frabricating PU/MWCNT aligned fiber were researched by orthogonal experiment method.In Chapter 3,the abilities of tactile sensor which are necessary for smart prosthesis were analyzed.A new type of flexible tactile sensor based on PU/MWCNT composite aligned fiber was proposed.The sensing elements were formed by depositing aligned fibers perpendicular to two parallel electrodes.Two sides of parallel sensing elements were orthogonal to each other and each one could detect one dimension of the distribution of the applied force.With combinating of the information acquired from both sides,the applied force was defined.With the resistance of one sensing element was as high as 1Gohm,a multiple high resistance measurement circuit was developed.The prototypes of the flexible tactile sensor were fabricated with the thickness less than 1mm.The static and dynamic abilities of these prototypes were also tested.In Chapter 4,the negative effects due to the integrating of the tactile sensor onto the prosthesis hand were analyzed to demonstrate the importance of recalibration process for the mounted tactile sensor.A mechatronic platform for static and dynamic performance tests on the mounted tactile sensor was proposed.The method for measuring the receptive-filed for the tactile sensor on curved surface was presented and based on this method a solution to locate the applied force with assistance of multiple sensing elements was also proposed.At the last part,a sensing finger prepared with standard piezoresistive and piezoelectric sensors installed was tested by the proposed platform and the performance of the platform was analyzed.In Chapter 5,the chief work and innovations of this dissertation were summarized along with insufficiencies and the further research subjects were also proposed.