Research Of Position Detection Method For A Novel 3-DOF Deflection Type PM Motor Based On Non-Contact Magnetometers

With the industrialization and artificial intelligence developing, the driving mechanism always needs to complete multiple directions of movement. When using the traditional motors to complete multi-DOF motions, usually more than one motors are required to operate simultaneously, which is with complex mechanical transmission mechanism and can not meet the requirement of modern science and technology development any more. The novel multi-DOF motors which can complete motions in many directions independently have been developed accordingly. The development of some theories such as motor theory, control theory and the lead of motors’ manufacture provide the basis for realizing the complex control of multi-DOF motors. With many magnetic materials such as alnico, ferrite, rare earth permanent magnet materials and composite permanent materials appears, the traditional motors which are in big size and complicated structure have been replaced by the PM made actuators with characteristics of simple structure, light weight, and convenient operation. The multi-DOF PM motors have been the hot spot of current research.Refer to the wide various structures of multi-DOF PM motors and their position detection systems, this paper puts forward a new position detection method for the 3-DOF deflection type PM motor which has the structure of double-layer stator coils and single-layer drum type rotor. Fundamental researches such as modeling the magnetic field, proposing a new rotor detection algorithm for application and the detection device design have been conducted.The main contents of this paper can be described as the following parts:1) This paper introduces the advantageous performances of the multi-DOF PM motors, and sums up the different structures of multi-DOF motors researched by domestic and foreign scholars up to now. On this basis, the classified description of 3-DOF motors’ rotor position detection methods has been presented. Various kinds of problems in the latest research progress are commended and the development prospect and tendency of the multi-DOF PM motors is discussed.2) PRO/E software is used here to simulate and model the novel 3-DOF PM motor, and the structure and size of the motor are introduced with its movement principle described in detail.3) The paper takes the cylinder PM with simple shape as an example, and builds PM models using the matured distributed multi pole(DMP) and the presented molecular current model methods in this paper. The MATLAB software is used here to validate these two established models, and the compared results show the mentioned methods are consistent with the errors are acceptable, which further validate the reasonability of the model.4) Aimed at the rotor of the novel 3-DOF motor discussed here with the special shape of drum type, the molecular current model is used to simulate and model it. It also discusses the method to detect the rotor’s position based on magneto-dependent sensors in detail. The relationship between the magnetic field and the angles of rotation can be obtained from the analysis which is closed to the polynomial approximation and the error is small.5) Based on the theoretical analysis of the motor’s magnetic field and detection system, the experimental platform for the rotor position detection system is constructed aiming at the representative ladder-type PM. The STM32F103RCT6 of the ARM series has been adopted as the core of the lower computer and the combined programming of VB and MATLAB has been employed by the upper computer to realize the interface display. On this basis, two methods of the position detection are proposed and adopted, one of them is multi-point measuring method using the traditional gauss meter and the other is automatically detection method. Using the two methods on the experiments of the rotor’s position detection, and comparative analysis is conducted. The experimental results of these two methods prove that the constructed automatic detecting system and the discussed algorithm of position detection in this paper are feasible and reasonable to some extent.