摘要
目前Bennett(BNT)机构根据回转副轴线的方向,分成非对称安装和线性对称安装两类。为了研究这两类机构的共性和区别,在杆件交错角(0,2π)的区域内,用相邻象限组合为4个区间,由S12(第1-2象限)区间和S34(第3-4象限)区间各得到1组非对称安装的左旋和右旋BNT机构;由S23(第2-3象限)和S41(第4-1象限)区间各得到1组线性对称安装的左旋和右旋BNT机构。把前后2组机构进行对比,只有轴线方向是非对称的,机构结构本身都是对称的。由于S12和S34区间的非对称安装机构,通过交错角的设定,可以转换为S41区间的线性对称机构,所以线性对称和非对称之间并无本质差别,4组机构本质是相同的1组。因为S41区间机构的运动副的轴线方向指向相同,轴线的正方向与相邻杆内角逆时针的角位移方向一致,所以把S41区间改用交错角锐角表示的R41(第4-1象限)区间作为交错角的工作区间,就得到线性对称的右旋型和左旋型两种BNT机构基本类型,这两类机构的运动链是相同的,只是以不同构件为机架得到两种机构的形式。根据这些概念,左旋型和右旋型BNT机构,采用交错角锐角给出了统一的结构参数方程和含相邻杆内角表示的闭环位移方程。这种交错角为锐角的统一参数方程,简单,直观,便于应用。研究强调并补充了相邻杆的交错角不能在作用区间的同一象限选取的一个必要的约束条件。
At present,Bennett(BNT)mechanism can be divided into two types according to the direction of axis of revolute joints:Asymmetrical and linear symmetrical installation.In order to study the similarities and differences between these two types of mechanisms,using adjacent quadrants were used to form four intervals in the region of link stagger angle(0,2π).Then,a group of asymmetrically installed left-handed and right-handed BNT mechanisms are obtained based on the S12(quadrant I and II)and S34(quadrant III and IV)intervals,and a group of linearly symmetrically installed left-handed and right-handed BNT mechanisms are obtained based on the S23(quadrant II and III)and S41(quadrant IV and I)intervals.Comparing these two groups of mechanisms,only the axis is asymmetrical while the structure itself is symmetrical.Since the asymmetrical installation mechanisms in the regions of S12 and S34 can be transformed into linear symmetrical mechanisms in the region of S41 by setting the stagger angle,there is no essential difference between linear symmetrical and asymmetrical mechanisms,and these two groups of mechanisms are essentially the same one.Because the joints within the mechanism in the region of S41 have the same axial direction,and the positive direction of the axis is the same as the anti-clockwise angular displacement direction of the inner angle of the adjacent links,so the interval of R41(quadrant IV and I)represented by the sharp angle of the stagger angle is used as the working interval of the stagger angle,then two basic types of BNT linear symmetrical mechanisms,i.e.,right-handed and left-handed,are obtained.The kinematic chains of these two types of mechanisms are the same,but they are obtained by taking different components as the frame.According to these concepts,aiming to the left-handed and right-handed BNT mechanisms,the uniform structural parameter equations and the closed-loop displacement equations with the inner angles of adjacent links are given by using the stagger sharp angles.This unified parametr
作者
鹿玲
张一同
牟德君
胡波
卢文娟
LU Ling;ZHANGYitong;MU Dejun;HU Bo;LU Wenjuan(School of Mechanical Engineering,Yanshan University,Qinhuangdao 066004;Heavy-duty Intelligent Manufacturing Equipment Innovation Center of Hebei Province,Yanshan University,Qinhuangdao 066004;Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System,Yanshan University,Qinhuangdao 066004)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2020年第9期9-17,共9页
Journal of Mechanical Engineering
基金
河北省自然科学基金(E2011203193)
河北省杰出青年基金(E2017203094)资助项目。
关键词
BENNETT机构
约束条件
交错角
结构参数
闭环位移方程
Bennett mechanism
constraint condition
stagger angle
structural parameters
closed-loop displacement equation
