Research Initiation: Development of a Spherical Stepper Wrist Motor

本研究的目的是为创建一个能够在单个关节中进行三度定向运动的球形腕步进电机建立理论基础。球关节型球腕电机具有结构简单、设计紧凑、工作空间中间除边界处无奇点、转子离心力不平衡等特点。在高速等离子体和激光切割等要求末端执行器快速、连续和各向同性定向的场合，球形腕步进电机具有重要的应用价值。研究将集中在三个方面。首先是使用有限元技术预测给定设计的磁场和磁阻力，这也将提供对设计参数对扭矩和分辨率的影响的良好理解。第二种是使用非线性规划技术进行优化，以在指定分辨率下最大化扭矩，同时最小化重量和体积。第三个领域是开发两级控制方案，以预先规划最佳轨迹并开发具有良好抗干扰性的方向控制律。

The objective of this research is to establish a theoretical basis for the creation of a spherical wrist stepper motor capable of three degrees of orientation motion in a single joint. The ball-joint-like spherical wrist motor is characterized by its simplicity in structure, compact design and free from singularities in the middle of the workspace except at the boundaries and unbalanced rotor centrifugal forces. The spherical wrist stepper motor has significant applications where the end-effector is required to orient quickly, continuously and isotropically in all directions such as high speed plasma and laser cutting. The research will focus on three areas. The first is the prediction of the magnetic fields and reluctance forces for a given design using finite element technique, which will also provide a good understanding of the influences of the design parameters, on the torque and resolution. The second is an optimization using non-linear programming techniques to maximize torque while minimizing weight and volume for a specified resolution. The third area is the development of a two-level control scheme to pre-plan an optimum trajectory and to develop an orientation control law with good disturbance rejection.