新型气动弯曲关节的静态特性分析

Static Characteristic Analysis of a New Type of Pneumatic Bending Joint

针对现有气动弯曲关节在低气压下弯曲角度受限制的问题,将两个气动柔性驱动器(FPA)作为弯曲关节驱动源,利用结构夹角实现关节的弯曲动作,并设计了一种新型气动弯曲关节.该关节包括一个T型结构、两个可以绕着转轴做圆周运动的转动结构和两个对称分布的FPA,FPA的两端固定在T型结构和转动结构上.通过改变两个FPA的内腔气压,使FPA伸长推动转动结构转动,使转动结构之间形成夹角,从而实现整体结构的弯曲运动.基于力矩平衡原理对弯曲关节中单个FPA的转动端进行静态特性分析.仿真分析和实验表明,相比于传统的单FPA弯曲关节,新型弯曲关节的角度气压比更高,即能在更低气压的条件下实现更大角度的弯曲任务.同时,其弯曲角度和FPA的内腔气压呈非线性关系,弯曲角度随关节结构参数的改变而改变.

Aiming at the bending angle limit of existing pneumatic bending joints at low pressure,an idea of using structural angle to implement the bending action is proposed.And a new type of pneumatic bending joints with two flexible pneumatic actuators（FPAs） as its drive source is designed.This joint includes one T-type structure,two rotating structures which can perform circular motion around the hinge,and two symmetrical FPAs.And two symmetrical FPAs are fixed on the T-type structure and the rotating structure.The two FPAs stretch to push rotating structure to move when inner air pressures are changed,which leads to an angle between rotating structures,and thus bending motion of the joints is achieved.The static characteristics of the turning end of FPA on the bending joint are analyzed based on the moment equilibrium principle.Simulation analysis and experimental results show that angle-pressure ratio of the new pneumatic bending joint is higher than traditional ones.It means that the larger bending angle can be gotten at lower pressure.Besides,the bending angle of the bending joint is nonlinear with the air pressure inside the FPA and the bending angle changes with the structure parameters.