Hall-sensor-based orientation measurement method in three-dimensional space for electromagnetic actuators

This paper proposes an orientation measurement method of a novel permanent magnet spherical actuator with 3D magnet array based on several hall sensors. This measurement method could avoid additional inertial moment and friction, as there is no contact between the measurement system and the rotor. And the accuracy of Hall sensors could be enhanced by the higher flux density produced by the 3D magnet array. A novel distribution of Hall sensors is proposed in this paper. Compared with the magnetic field model formulated analytically, the rotor orientation could be derived from the measured value of flux density by these Hall sensors. Numerical computation is utilized to validate the accuracy of the analytical equations between the orientation of rotor and the measured value of Hall sensors. Also the numerical computation shows that the accuracy of the orientation measurement method is influenced by the 3D magnet array. These researches could be used for subsequent control implementation of the novel permanent magnet spherical actuator.