| Intelligence is a significant direction for the latest development of Robotics Technology,yet the realization of intelligence is still largely limited by a key technology – Sensor Technology.Progresses have been slow in the research and development of sensor technology,which has restricted the development of intelligent robot.The researches on the sense simulations of human touch are mainly conducted in the field of fast and highly-sensitive recognition to force signal,as well as requiring the sensors being similar to human skins in the features of softness and flexibility to any surfaces.Currently,the detecting technology designed specially to strong force signal(>10 kPa)has entered a mature stage,however the detecting technology for weak force(<5 kPa)and three-dimensional force signal is still remained to be completed,and the manufacturing skills on flexible sensor devices are still in urgent need for optimization.Considering the above factors,this project aims to adopt graphene sheet in structured array as mechanical sensitive material,through optimizing the structure design of sensor structure and manufacturing technology to produce force sensor with high-performance,and utilizes integrated signal collecting system to realize the rapid acquisition and analysis of force signals.The author made use of interface pressure resistance effect and designed a flexible three-dimensional force tactile sensor based on graphene sheet.The overall structure of sensor contains three main parts,namely,surface embossment layer,piezoresistance layer,and flexible electrode.Through analyzing on the mechanism produced by interface resistance,the author researched on the detecting principle of the three-dimensional force of sensors in details,and verified the principles with finite element simulations.The author further produced piezoresistance layer with graphene sheet through the application of Silicon Lithography Technology,Wet Etching Process,Cuffed Casting Membrane Technology and Layer-By-layer Self-Assembly Technology(LBL).Flexible electrode layers were designed,formulated and installed as the piezoresistance units of flexible three-dimensional force sensor,and then performance detecting tests of positive pressure and general three-dimensional force pressure were conducted to the units.Results showed that when the contacting pressure is smaller than 500 Pa,the Sensitivity of sensor is-1.71 KPa-1;when the pressure is between 500 to 5000 Pa,the Sensitivity is-0.0178 KPa-1.The response and reply time for the above two forces were 7.5 ms and 7.4 ms individually.The sensor can be used for the rapid and highly-sensitive detection of positive pressure,shear force and force from any directions in space.The lowest detectable limit of sensor is 2 Pa,and it is of great stability in force detection.The author further constructed signal acquisition circuit of array tactile sensor,firstly adopted the method of partial pressure and designed signal detection circuit,and collected the output signal of each array sensor element through high-speed gate chip CD4051,and then used the A/D Digital-to-Analogue Conversion of STM32 single chip to realize the conversion of signal from analog quantity to digital quantity,analyzed the digital signal with STM32 single chip,eventually output and display the signals through PC.Coupling analysis were conducted to the tactile sensor,and results showed that the coupling calculation results were influenced by the designing principle,measurement mode and the production and manufacturing precision of sensors,therefore the output signals of each direction would be disturbed by several external factors.Considering these,the author adopted no-linear BP neural network for the three-dimensional force decoupling researches to tactile sensors.The maximum error of decoupling calculation result is 4.3% FS,hence the author wrote decoupling interface in order to realize the decoupling researches of sensors. |
PDF Full Text Request