两自由度导管机器人的动力学仿真研究

Dynamic simulation research on a 2-DOF catheter robot

对三形状记忆合金(SMA)螺旋弹簧驱动的导管机器人的动态特性进行了研究。首先基于综合力学方程、SMA的本构方程和传热方程建立了动力学模型,然后针对双输入双输出(TITO)系统的2个自由度间存在强耦合和因SMA的高度非线性使得难以采用解耦实现对相邻SMA驱动器控制的现象,设计了具有混合结构的模糊控制器。它用传统的模糊控制器控制系统的2个自由度,同时用耦合模糊控制器补偿2个自由度之间的耦合作用。仿真结果表明,所推导的动力学模型能够正确描述这种结构的特性,并且混合模糊控制器具有良好的控制效果。

This study focused on the dynamic behavior of an active catheter actuated by 3 shape memory alloy （SMA） coil springs. The bending mechanics, the SMA＇s characteristic described by Liang＇s model, and a heat transfer model were combined to derive the dynamic model. A mixed fuzzy controller （MFC） was designed under the consideration that it is difficult to control 2 adjacent SMA actuators by decoupling since there exists strong coupling effect between two degrees of freedom （DOFs） of such a two-input two-output （TITO） system, and the SMA possesses high nonlinearity. In the controller two traditional fuzzy controllers control 2 DOFs respectively and two coupling fuzzy controllers compensate for the dynamic coupling between 2 DOFs. The simulation results indicate the derived dynamic model can accurately describe the characteristic of such a structure and the MFC possesses an effective performance.