菠萝采摘混联机构的设计与运动学分析

Design and kinematic analysis of pineapple picking hybrid mechanism

针对菠萝采摘机构工作空间大、刚度和承载能力高的要求,提出一种由1R2P串联机构和球面2自由度冗余驱动并联机构串联组成的混联构型方案。将混联机构简化为一个5自由度空间开式运动链,采用D-H方法建立运动学方程,得到位置正反解。对球面2自由度冗余驱动并联机构进行尺度设计,得到位置反解。应用ADMAS软件建立虚拟采摘机构模型,进行运动轨迹规划和仿真分析。结果表明,机构各杆件在运动空间范围内约束条件没有发生破坏,杆件之间无结构干涉,运动关节速度和加速度变化平缓,无突变。杆件尺寸参数设计合理,为菠萝采摘设备的研制提供了理论依据。

To satisfy large workspace,high stiffness and load bearing ability of the pineapple picking mechanism,a hybrid mechanism scheme,which is composed of a 1R2P serial mechanism and a 2-DOF spherical parallel mechanism with actuation redundancy,is put forward in the paper.The hybrid mechanism was simplified to a 5-DOF space open kinematic chain.Through establishing the kinematic equations with D-H method,the position forward and inverse solutions were deduced.Main dimensions of the 2-DOF spherical parallel mechanism were designed,and its inverse equations were obtained.By applying ADMAS software,virtual picking mechanism model was created,motion trajectory was planned,and kinematic simulation analysis was carried out.Simulation results show that constraint relations among rod bodies are not damaged in the motion space,no structural interference problems happen,velocity and acceleration of motion joints change smoothly.Design of the rod size parameter is reasonable,and it provides a theoretical basis for developing pineapple picking equipment.