A Novel Multifunctional Angular Position Sensor with Magnetic Fluid

Abstract

The achievement of inclination angle and inclined direction simultaneously is highly recommended in many application fields. But many researchers are concerning on measuring only one angular parameter which has a limited application. Based on the principle of inclinometer, the paper proposes a sphere-shape angular position sensor for testing two angular parameters based on multifunctional sensing technique. The proposed sensor is mainly characterized in the following respects. First, inclination angle and inclined direction are measured simultaneously with a single structure. Second, a full-range measurement is achieved, which indicates the inclination angle ranges from 0• to 180• and the inclined direction ranges from 0 • to 360• . Its compact and single structure permits widely applications on automobile, robotic system, health science and so on. We herein discuss the configuration of the sensor and its geometrical analysis. A prototype is built, the evaluated results of which examine the feasibility of the sensor. Two angular parameters are successfully evaluated by analyzing the sample points using 2-D cubic spline interpolation.Sphere-shape container is selected instead of utilizing the common cylinder shape because of its uniform to every direction. Magnetic fluid is selected as the inertial element of sensor attributable to its liquidity and electromagnetism character. The liquidity of magnetic fluid causes the flowing to the position with the lowest gravity center and its electromagnetism character permits it to be taken as the core of a coil for amplifying the self-inductance, whose value is only related to the nip angle of coil section and fluid surface.The configuration of the prototype is shown as Fig. 1 Analytic geometry is utilized for analyzing the relationship between three nip angles and angle parameters. Three inductances can be expressed by θ and φ as its variables.where α1, α2 and α3 are the nip angles of three coil sections and the horizontal.In order to prove the feasibility of the sensor and compose the database for data processing, three inductances are measured at some sample points. Fig. 2 shows the surface composed by points with L1, L2 and L3 as their coordinates. A block surface can be obtained, each point on which indicates a unique direction of the whole space. The two center points of the surface are the positions that θ = 0• and θ = 180• .Each contour line displayed represents the inclined direction and the radial distance from the center represents the inclination angle. 2-D cubic spline interpolation is chosen as data processing method due to its smooth peculiarity and high accuracy. The evaluated results prove the feasibility of the proposed sensor. MemberA sphere-shape angular position sensor for measurement inclination angle and inclined direction simultaneously based on multifunctional sensing approach is proposed, which is characterized in the following respects, such as the measurement of two angles, a full-range measurement, and has a compact and single structure. Three...