Analysis Of Electromagnetic And Dynamic Control Of Hybrid Driving Multi-DOF Motor

With the continuous innovation and development of the intelligent motion driving device,it is widely concerned that motion with multiple DOF can be achieved in a small space.The realization of multi-DOF motion by using multiple motors is required to depend on the combinatorial connection for the driven mechanism,and the direct drive for the multi-DOF motor as the driving mechanism can avoid many disadvantages caused by the intermediate transmission,such as the large volume of equipment,strong nonlinear coupling,and low motion precision.In order to solve the problems of low accuracy and poor motion control of multi-DOF motors in 3-dimensional space,a hybrid-driven 3-DOF motor is proposed,which consists of a self-rotating electric module and a deflection electric module,each adopting a set of control circuit.The circuit is controlled separately to avoid electromagnetic coupling between them,thus simplifying the control mechanism,which can achieve high-speed and stable single-DOF rotation motion and continuous and precise 2-DOF tilt operation.Under the coordinated control of two modules,the motor moves in a variety of 3-DOF motion around its static equilibrium position.The main researches of this paperare as follows:1)The basic structure of the hybrid drive motor is introduced.It is divided into two types of drive modules: rotation and deflection,which can be independently operated to achieve high-speed rotation and precise tilt of the motor,and can also run synchronously to realize three-degree-of-freedom motion in space.2)The magnetic field characteristics of the motor's rotating permanent magnets are optimized and improved by using the function of the Halbach array with strong magnetism gathering and the effect on the shielding of magnetic circuit.Combined with the finite element structure of the motor,the magnetic field distribution laws of the rotation module and the deflection module are analyzed in a static magnetic field.An analytical model of the magnetic field is established by solving the Laplace equationunder the specific boundary conditions.By comparing the calculation results of the finite element method with the derivation results of the analytical method,the correctness of the analytical method model and the accuracy of the finite element model have been mutually verified.3)In order to comprehensively measure the performance index of the motor,the finite element calculations of the stator core loss,winding copper loss and permanent magnet eddy current loss of the motor are performed under different magnetization methods of the permanent magnet.It is concluded that the loss value of the motor is small under Halbach array magnetization when the output power of the motor is constant.Meanwhile,the calculated loss is used as a heat source,and the temperature rise effect and stress deformation of the motor are analyzed in a magnetic-thermal-solid multiphysics field.The rotation torque and deflection torque of the motor are solved respectively by adopting the virtual displacement method and the spatial distribution characteristics of the output torque are analyzed.The results show that the motor has good torque characteristics when the coil current is in a reasonable range.4)Based on the dynamic simulation software ADAMS,a virtual prototype model of the motor is established.By adding motion constraints,the control strategy of the motor corresponding to rotation operation and deflection operation is planned,and the kinematics simulation of the virtual prototype technology is realized.In the independent rotation movement,the operating mode of rigid body system and rigid-flexible coupling system are set;in the independent deflection operation,the motion mode of deflection along the axis and multi-angle tilt are designed.The rationality and correctness of the independent operation of two drive modules can be verified.5)The dynamic mathematical model of the hybrid drive motor is obtained through the rotation coordinate transformation of the rotor part of the motor and the derivation of Lagrange's second equation.By applying an external load,the rotor trajectory is planned,thereby realizing the dynamic simulation of three-degree-of-freedom motion of the motor under the static equilibrium position,and making it have the smoothness of the rotation motion and the accuracy of the deflection operation.It further illustrates the feasibility of the motor structure suitable for cooperative control,and provides a basis for subsequent trajectory tracking control.6)Based on the construction of the joint simulation platform,the controlled object is derived by ADAMS software,and the control system is designed in MATLAB software.Aiming at the nonlinear and strongly coupled dynamic system,the sliding mode control is selected as the dynamic control algorithm to study the trajectory tracking of the motor rotor shaft.By combining the dynamic model of the motor,the S function is written to complete the design of the controller.The simulation results show that the joint simulation interface and sliding mode control algorithm canrealizethe trajectory tracking of hybrid drive motors.