可重构混联机械手--TriVariant的误差建模与灵敏度分析

针对少自由度并联构型装备,必须通过误差建模将影响末端可控和不可控误差的几何误差源进行分离,从而指导机构的精度设计和运动学标定的问题,以5自由度混联机械手TriVariant为对象,研究一种少自由度并联构型装备的误差建模方法。该方法可有效分离出影响末端不可控误差的几何误差源,得到由UP支链连架胡克铰的加工和装配误差,以及套筒导轨扭角误差引起的末端姿态误差为不可控误差,从而得到仅需控制恰约束支链的制造和装配误差,便可有效抑制末端的不可控姿态误差的重要结论。在此基础上,借助灵敏度分析方法,在统计意义下定量揭示出上述几何误差源对末端不可控姿态误差的影响。分析结果表明,胡克铰两轴线不相交误差对末端不可控误差的影响最大。

ERROR MODELING AND SENSITIVITY ANALYSIS OF RECONFIGURABLE HYBRID ROBOT MODULE TRIVARIANT

For the sub-6 DOF parallel kinematic machines (PKM),it's necessary to separate the geometric error sources which influence the compensatable and uncompensatable errors of the mobile platform by error modeling for the purpose of supervising the accuracy design and kinematics calibration.By taking the TriVariant,a 5-DOF hybrid robot,as an example,a novel approach for error modeling is presented for such robot. The geometric error sources affecting the uncompensatable position and orientation errors of the mobile platform can be identified through this approach.It can be concluded that the uncompensatable errors of the mobile platform are primarily dominated by the errors of the proper-constraint limb included by both the manufacturing and assembling errors of U joint and the twist errors of the tracks.The effects of the geometric error sources on the uncompensatable errors are also discussed by means of the sensitivity analysis.The analysis results show that the error brought by the deviation of the intersection of the two axes of the U joint takes the greatest effects on the uncompen- satable errors of the mobile platform.