Theoretical And Experimental Study Of Magnetic Liquid Inclination Sensor

The magnetic liquid combines the two physical properties of magnetism and fluidity,and based on these two unique physical properties,a magnetic liquid tilt sensor is produced.The tilt angle is measured by the change in the coil inductance caused by the small displacement of the inertial mass.The magnetic liquid tilt sensor has the characteristics of low cost,simple structure and high sensitivity,and can meet the performance requirements of the sensor.In this paper,a tilt sensor based on the second-order buoyancy principle is designed to explore various factors that affect the performance of the sensor.In this thesis,the magnetic field equation of the cylindrical magnet in space,the second-order buoyancy theory and the inductance formula of the induction coil are theoretically derived.The physical model of the magnetic liquid inclination sensor is established.The magnetic field is visualized by COMSOL and ANSYS finite element software.Description,the second-order buoyancy value is calculated according to the model.A second-order buoyancy test bench was built to measure the second-order buoyancy value of the composite magnetic core in the magnetic liquid.An inductance test bench was built to measure the influence of the position of the composite core inside the coil on the inductance value.Combining the inductance experiment and the second-order buoyancy experiment,the overall design of the sensor is optimized,and a suitable composite core is selected to build a test bench to measure the static output performance of the sensor.The conclusions reached are;1.By deriving the second-order buoyancy theory,it is found that the second-order buoyancy of the composite core not only provides it with upward levitation force,but also provides a restoring force for the composite core,so that the composite core can be placed in the horizontal position.Go back to the center.2.Through parametric modeling,it is found that the magnetic field strength of the model core is significantly enhanced when the core of the composite core is iron core.In order to understand the second-order buoyancy principle in depth,the magnetic field diagram is obtained by the finite element analysis method,which can visually see the trend of the magnetic field strength.3.The second-order buoyancy of the composite core will increase with the increase of the amount of magnetic fluid.In the scheme of the three composite cores selected,the cylindrical magnet receives the second-order buoyancy,and the circle with 30mm core The ring magnet receives the second-order buoyancy value to a minimum.4.Through the inductance experiment,the curve of the inductance of the coil and the corresponding depth of the inserted composite core is obtained,and further experiments are carried out to obtain the relationship between the length of the core and the change of the inductance of the coil.It is found that the longer the core length,the greater the slope of the curve when the composite core is inserted into the coil,that is,the sensitivity is higher.5.Test the performance of the sensor and obtain the relationship between the output voltage and the tilt angle of the sensor.It can be seen from the fitting curve that the sensor with the core of the composite core has better linearity within a certain range.