Design Of Magnetic Rubber Self-sensing Flexible Foot

With the continuous development of artificial intelligence technology and various fields are gradually becoming intelligent and informatized.The movement mechanism is also developing in the direction of informatization and intelligence.As a common component in the motion mechanism,the foot sole plays a variety of important functions in a complete motion mechanism.The sole of the foot faces a complex friction environment.During the movement of the mechanism,there are complex interaction forces between the sole of the foot and the friction contact surface.These forces are the main factors that affect the overall motion state of the mechanism.For the motion mechanism to perceive the changes in the external environment and its own force in real time,it is necessary to install a sensing unit inside the foot to sense the interaction force between the foot and the friction contact surface,so that the motion mechanism is informatized.In addition,setting a control unit in the motion mechanism can enable the motion mechanism to adaptively regulate the motion state,thereby achieving intelligence.Existing research shows that magnetic sensitive rubber is a smart material prepared by filling micro-nano-level magnetic particles with high molecular polymers,and its physical properties will change reversibly under the action of an external physical field.The flexible foot designed based on the smart material magnetic rubber,because of its controllable surface roughness,elastic modulus and magnetic field force under the excitation of a magnetic field,it has been extensively and deeply researched and applied by many scholars and engineers at home and abroad test.Since the role of the foot is to perceive the interaction between the outside world and it in real time(friction,positive pressure),and as a carrier for regulating the motion state of the mechanism,the foot needs to have both the sensing function and the motion control carrier function.For this reason,this thesis uses magnetic rubber as a matrix to design the foot,and study the change of the friction coefficient and the force of the magnetic rubber in different magnetic field environments.The other is to prepare multi-walled carbon nanotube silicone rubber polymer and use it as the sensing unit of the magnetically sensitive rubber sole.The main research work of this thesis is as follows:1.Describes the engineering background and research significance of magnetic rubber in the field of magnetic control friction and sensing,summarizes the current research status of the conductive properties and sensing characteristics of magnetic rubber with conductive particles,and clarifies the flexible foot based on magnetic rubber There are problems in the design of friction control and perception function,and the main research work of this article is proposed.2.Starting from the friction braking problem of the foot,according to the two important factors that affect the friction force: positive pressure and friction coefficient,neodymium iron boron magnetic sensitive rubber is selected as the material for preparing the base of the foot,and the magnetic field of different volume fractions is explored.The friction characteristic of sensitive rubber changes,it is found that the friction coefficient of magnetized isotropic magnetic sensitive rubber with 10% neodymium iron boron volume fraction can increase by 125%,and it is used as a material designed for the sole.3.In order to solve the problem of perception of the magnetic rubber feet,this article proposes two research schemes: one is to directly add multi-walled carbon nanotubes to the magnetic rubber matrix to make the magnetic rubber have good conductivity,and use the magnetic rubber The sole is used as the sensing unit;the second is to prepare the multiwalled carbon nanotube silicone rubber polymer and use it as the sensing unit of the magnetically sensitive rubber sole.Through the piezoresistance experiment test,it is found that the piezoresistive properties of the multi-walled carbon nanotube silicone rubber polymer with a volume fraction of 3% are the best.The corresponding exponential function is fitted through the MATLAB fitting toolbox and used as the sensor of the foot.Unit,design a sensing detection circuit according to the stress-resistance relationship.The designed sensor detection module is verified,when the actual pressure is large,the measurement error is small,and the maximum measurement error is 10%.Overall,most measurement errors are less than 6%.4.In order to increase the control range of the friction of the feet,parallel motion type feet and sandwich type feet are designed according to the two working environments of flat ground and vertical wall surface.The main structure of the foot includes: excitation coil,excitation coil packaging device,foot base,sensing unit,information acquisition and processing module,and connecting parts.Through COMSOL simulation,it is concluded that the friction force of the sandwich-type foot can be controlled by current.