二级半转机构运动特性分析及其轮腿构型设计

Double-half-revolution Mechanism Motion Characteristics Analysis and Its Wheel-leg Configuration Design

基于动物肢体运动的不对称性原理,提出一种可以模拟步行运动效果的二级半转机构,它由一级转臂、二级转臂和两个跨步杆构成。通过机构运动步态分析,得出其各关节需要满足的运动耦合关系。分析机构运动时的杆件几何关系,找出机构的运动驻点和固有特征线。基于二级半转机构的步行运动特性,提出两种探测车轮腿机构的构型方案:同侧偏置式和双侧分置式。其中,同侧偏置式轮腿机构构型方案采用二级串联的行星轮系来实现二级半转机构的运动特性,其一级转臂和二级转臂分别是所在行星轮系的行星架,同时它们又是齿轮箱体。通过机构干涉分析,得出轮腿机构不发生干涉的条件。双侧分置式轮腿机构构型方案采用双曲柄四杆机构来实现二级半转机构的固有运动几何特性。基于COSMOS Motion软件,对该二级半转轮腿机构进行虚拟样机运动仿真,获得机构各转动关节的运动轨迹曲线以及该轮腿机构的上下起伏度。通过轮腿机构样机行走试验,验证其具有良好的动态运动性能。

Based on the asymmetry principle of the animal limb motion,a double-half-revolution mechanism is proposed,which can imitate walking movement effect,and is comprised of one first swiveling arm,one second swiveling arm and two striding rods.Through gait analysis of mechanism motion,their motion coupling relations among the joints are obtained.By analyzing the rods geometric relations when they rotate,the stagnation points and inherent characteristic line of double-half-revolution mechanism are found out.Based on the walking motion characteristics of double-half-revolution mechanism,two configuration schemes for wheel-legged mechanism are proposed： ipsilateral offset type and bilateral division type.The ipsilateral offset configuration scheme adopts two tandem planetary gear trains to achieve the motion characteristics of double-half-revolution mechanism,the first swiveling arm and second swiveling arm are their planet carriers（also as gearbox casings） of the planetary gear trains.Based on interference analysis,its non-interference condition is obtained.The bilateral division configuration scheme adopts double crank four-bar linkage mechanism to achieve the inherent geometric characteristics of double-half-revolution mechanism.Based on motion simulation in COSMOS Motion software,the motion trail curves of joints of the wheel-legged mechanism are obtained,and its fluctuation is analyzed.Through making experiments by the wheel-legged mechanism prototype,its dynamic movement performance is verified.