A New Robot Tactile Sensor Based On Distributed Electric Field

Robot tactile sensing technology is one of the key techniques of intelligent robots.Contact position information is essential for a robot under unexpected collision.With the detection of contact position,robot can get the direction of obstacle around and make smart decision to directly reduce contact force and avoid secondary collision.So far,most tactile sensors are made up of arrays,which can reach higher accuracy.But as its discontinuous construction,disadvantage is unavoidable that they have to be scanned one by one which cost time and CPU resources,especially when large area is to be detected.On the contrary,the structure of non-array tactile sensors are compact,easily to drive and with a few leads.As they are continuous,non-array type tactile sensor can effectively sense information of every point of its ranges.Higher resolution of space means more suitable for detecting large area.This study is supported by the National Natural Science Foundation of China(No.51175084).With a deep understanding of various tactile sensors based on various methods,a new robot tactile sensor based on electric field is proposed in this paper.The sensor proposed is designed as a whole and can effectively detect contact position and on-off information of contact force.It is thin and soft,with few leads and high space resolution,which is capable of covering large areas of robot arm.Firstly,this paper demonstrates uniqueness theorem of electrostatic field and steady current field,and explains the basic principle of detecting contact position using tow electric fields.Then distributions of uniform and non-uniform electric fields are discussed,mathematical models are created,and two types of tactile sensor are designed as well as factors that affect force threshold are listed.In addition,3D finite element model is created in software COMSOL Multiphysics,simulations of its accuracy under pressing in a point shape and an area shape are made?More simulations are done to describe the relationship between touch area situation and detected error,which verify the rationality and feasibility of sensor proposed.Taking physical properties into consideration,appropriate material is selected to make a sensor sample.Finally,off-line accuracy test shows good property of sensor sample.And in the on-line servo experiments based on a 6-DOF industrial robot,results show that sensor proposed performs well and is effective to be used in protecting industrial robot.This paper designed a new type robot tactile sensor which is not made up with arrays,which is effective in sensing contact position of robot surface and on-off information of contact force.It can be not only used to improve safety of industrial robot,but also in various sever robots.