Modeling And Optimization Design Of A Novel 3-DOF Deflection Type PM Motor

With the development of industrial technology such as the robotics and intelligent flexible systems, the need to achieve multi-degree-of-freedom motion in the working space is required. But the traditional implemented method is to link multiple single degree-of-freedom motors together by transmission mechanisms, which will not only cover a huge volume but also increase the accumulation of errors affecting the accuracy. At the same time, a large number of the reduction gears used in the system increase the moment of inertia and the internal friction of the torque, weakening the dynamic performance of the motor. So the traditional realization method of multi-degree-of-freedom motion has been far from satisfying the requirements of modern industry. This paper presents a novel type of permanent magnet rotor deflection type of three-degree-of-freedom motor, which not only can realize multi-freedom-degree motion in a single motor, but also has been greatly improved than traditional driving structures in terms of the volume, the accuracy and the stability, etc. This paper studies the structure and the working principle of the motor, and gives the electromagnetic and dynamic models. Furthermore, the structure parameters of the motor are optimized.These main contents of this paper mainly contain follows:1) A novel multi-DOF deflection type PM motor is researched, and its structure and the working principle are analyzed in detail. The electrifying strategy is also investigated. With the main spin rotation movement, the motor can achieve a range of deflection movement.2) The analytical and the finite element methods are used for the motors’ electromagnetic modeling to analyze the air gap flux density and torque characteristics of spin and deflection rotation. In the spherical coordinate system, by solving the Laplace equation, this paper establishes the magnetic field model of the motor, and establishes the spin and deflection rotation torque model of the motor using Maxwell stress tensor method. As a comparison, the air gap flux and the torque are modeled and simulated by using the finite element simulation software ANSOFT MAXWELL. Furthermore the effect of the number of motor’s magnetic pole pairs on the performance is analyzed to complete a preliminary optimization of the motor.3) The dynamics model of the motor is established by solving the dynamic differential equations of the motor and is simulated by MATLAB. Then, by combining the ADAMS and the SOLIDWORKS softwares, the three-dimensional physical parameters model of the motor is set up. The output torque curves of the motor are derived by the dynamic simulation, which predicts the operation performance of the motor systerm in real system level.4) This paper uses response surface methodology as the optimization method of the torque of multi-DOF deflection type PM motor. The Taguchi algorithm is applied to select the structural parameters that affect the motor’s torque greatly. Then, based on the central composite design(CCD), the sample point group is constructed. The response surface models of the spin and deflection rotation torques are presented through the small scale tests.5) The variance of the response surface model is analyzed to verify the linear relationship between the response values and variables. Based on the pre-optimized design, the permanent magnet rotor deflection type of three-degree-of-freedom motor prototype is designed and manufactured, and the prototype experiment verifies the reliability of the response suface model.