并联机器人具有负载能力强、速度快和刚度大等优点,弥补了串联机器人的不足,使得并联机构成为一个潜在的高速度、高精度运动平台。针对所设计的6杆并联测量机,为解决奇异位形处的动力学性能变差和产生不可控运动等问题,基于主、被动关节所在三条支链的约束关系,推导建立了6杆并联测量机的运动学模型和闭链约束方程,将奇异性求解转化成LMI的极值问题,利用归一化GA算法仅通过15代计算实现了空间奇异位形的求解,精度达到1.168 9×10-5。所用方法避免了常规基于雅克比矩阵进行奇异性求解时产生的大量计算,具有求解精度高、收敛速度快等明显优势,为实现高速、高精度检测奠定了理论基础。
The parallel robots have some advantages of strong load capacity,fast speed moving and large stiffness,it makes up for the deficiency of series robot and will become a potential motion platform with high speed and high precision. The kinematics model and closed chain constraint equations are established based on the constrain relationship between the primary and passive joints in three chains for solving these problems of poor dynamics performances and uncontrolled motion about the designed six- bar parallel measuring machine.The calculation of space singularity of measuring machine is realized through the calculation of 15 generations by using normalized genetic algorithm through converting the singularity solution into calculation of LMI extreme-value,the normalized genetic algorithm calculation accuracy reaches 1. 689 × 10- 5. The proposed method avoids of mass computation compared to the traditional way based on the analysis of Jacobin matrix and has obvious advantages of high accuracy and fast convergence rate. The theory foundation is established for realizing measuring work in high speed and high accuracy.