基于磁通叠加原理的变刚度关节设计与特性研究

基于磁通叠加原理,提出了一种机器人变刚度关节,在减少了关节质量的同时增加了关节刚度的调整速度和运动范围。阐述了通过电信号直接调整永磁-电磁混合式变刚度装置中磁通量,实现刚度改变的工作原理,并以此原理设计关节整体机构。根据磁通连续性原理和虚位移法建立了关节刚度模型,并给出关节刚度随电流和关节位置的变化关系。以变刚度关节刚度模型为基础,设计了变刚度关节位置与刚度协调控制器,搭建了变刚度关节的原理样机。实验结果表明,基于磁通叠加原理的变刚度机器人关节可以实现关节刚度的快速调节,关节的位置和轨迹跟踪精度随着刚度的增加而增加,随着频率的增加而降低。

Design and Characteristics Study of Variable-stiffness Joint Based on Principle of Magnetic Flux Superposition

The variable permanent magnet spring joint made up of the permanent magnet spring has good nonlinear stiffness change performance, which can improve the safety of human and robot interaction. To further improve the range of motion and stiffness performance of the robot, based on the principle of magnetic flux superposition, a type of robot variable stiffness joint was proposed, which increased the adjustment speed of the joint stiffness and motion range of the joint, while reducing the joint mass. The variable stiffness working principle of adjustment of magnetic flux in permanent magnet-electromagnetic hybrid variable stiffness device by electrical signal was elaborated, and the overall mechanism of the joint was designed based on this principle. The joint stiffness model was established according to the magnetic flux continuity principle and the virtual displacement method. And the relationship between the joint stiffness with the current and the joint position was given. Based on the variable-stiffness joint stiffness model, the position and stiffness coordination controller of the variable-stiffness joint was designed, and the principle prototype of the variable-stiffness joint was built. The proposed variable stiffness robot joint based on the magnetic flux superposition principle had lighter weight and better structural stiffness change performance and motion accuracy. The overall joint mass was 1.1kg and the joint can rotate from -180° to 180°. The experimental test results showed that the variable stiffness robot joint based on the superposition principle of magnetic flux can realize rapid adjustment of joint stiffness, and the adjustment time was only 0.133s. The position and trajectory tracking accuracy of the joint was increased with the increase of stiffness and decreased with the increase of frequency.