Research On Capacitive Proximity Sensor For Target Detection

Perceiving the external environment is an important ability for robots,which can reduce the safety risks in the operation of robots.Capacitive proximity sensors can help robots sense surrounding objects,which is of great significance to robots.However,the sensing range of ordinary capacitive proximity sensors is extremely limited,and the assistance effect for most robots is not good.In response to this problem,the thesis designs a self-capacitance proximity sensor system with target detection function,which can not only achieve a relatively farther proximity sensing range,but also have the ability to measure distance,discriminate the material properties of objects,and achieve three-dimensional positioning.The main work of this thesis is as follows:(1)Combined with practical application scenarios,this thesis proposes a self-capacitance proximity sensor model for target detection,and theoretically analyzes its functions of measuring distance and discriminating materials.The thesis optimizes the sensor geometry based on the COMSOL simulation software.By comparing the simulation results of the square,circular and rectangular sensors with the same area,it is determined that the square is the best geometry.Moreover,the effective effect of the active shield electrode on helping the sensor to achieve farther proximity sensing is verified by simulation.(2)The capacitive proximity sensor system is divided into three parts: capacitive sensor,capacitive measurement circuit and control circuit by the idea of modularization in this thesis.In terms of hardware,in order to ensure the accuracy of capacitance measurement,the thesis selects a high-resolution capacitance-to-digital conversion chip with the main control MCU,and completes the design of the entire system circuit according to the actual needs.In software,the thesis realizes the control of the whole system by implementing defined communication.(3)Aiming at the application of sensors in distance measurement and material recognition,the thesis uses different target objects to conduct proximity experiments.And according to the experimental results,the sensing range of the system to each target object and the corresponding expression of the capacitance relative to the distance are obtained,and the functional application of the sensor system is analyzed and verified respectively.For the application of sensors in three-dimensional positioning,the thesis uses stainless steel balls as the target object to complete the proximity experiments in the presence and absence of an intermediate vision occlude,and the feasibility of using multiple sensor systems for 3D positioning of the ball is analyzed according to the experimental results.