基于螺旋理论的钢带并联机器人力学特性数值分析

Numeric analysis of mechanics of steel band parallel robot based on screw theory

为了克服传统的并联机器人工作空间较小、奇异性与运动学正解分析复杂的缺点,拓宽并联机器人的应用领域,提出一种新型的六自由度钢带并联机器人机构形式.阐述了钢带并联机器人结构组成、工作原理、钢带运动副关键技术,并对不同结构的钢带进行了有限元分析,得到结构参数改变时钢带能承受的失稳力.基于螺旋理论建立了钢带并联机器人力学模型,对刚带并联机器人受力进行数值计算,得到钢带并联机器人不同位姿与结构对各钢带受力的影响规律,为优化钢带并联机器人的结构与运动参数提供理论依据.研究结果表明：弯曲截面结构的钢带承压能力较好,钢带失稳力随钢带圆弧截面中心角、钢带厚度增大而增大,随钢带长度增大而减少.其他结构参数一定,载荷力为400 N时,动平台外接圆半径为210 mm,动平台沿Z轴运动范围受卷筒装置中钢带长度的限制,沿Y轴运动范围为-745~680 mm,沿X轴运动范围为-675~675 mm,动平台绕Z轴旋转角度范围为-87°~87°,绕Y轴旋转角度范围为-77°~77°,绕X轴旋转角度范围为-90°~66°.

A new six degrees of freedom（DOF）steel band parallel robot（SBPR） was invented to overcome the existing shortcomings（such as small work space,complicated singularity and forward solution） and broaden the application field of parallel robots.The structure,principle of SBPR and the key technologies of steel band motion pair were analyzed.The finite element models of different steel bands were established to simulate their instability and identify the instability force with different structure parameters.Based on screw theory,the mechanic models of SBPR were established to calculate the forces acting on the steel band and acquire the influences of different postures and structures,which provided theory basis for optimizing the structure and motion parameters.The results show that the steel band with arc-shaped cross section has strong ability of supporting pressure load.With the increasing of the arc angle and thickness of the steel band,the instability force increases.With the steel band length increasing,the instability force decreases.When other structure parameters are constant and the load force is 400 N,the circumcircle radius of the moving platform is 210 mm,the motion range of the moving platform along Z axis is limited by the length of steel band in the reel parts,the motion range of the moving platform along Y axis is-745-680 mm,the motion range of the moving platform along X axis is-675-675 mm,the angle of the moving platform around Z axis is between-87 ° and 87 °,the angle of the moving platform around Y axis is between-77 ° and 77 °,and the angle of the moving platform around X axis is between-90 °and 66 °.