基于运动/力传递性能的索并联机器人尺度综合研究

Dimensional synthesis of cable-driven parallel robots based on the motion/force transmission performance

索并联机器人使用柔性绳替代传统并联机器人的刚性连杆,以控制末端动平台,在搬运、医疗康复等领域得到了广泛应用。为了解决索并联机器人设计过程中存在的尺度综合问题,对索并联机器人的性能评估指标进行了研究。首先,根据螺旋理论确定了索并联机器人驱动输入与运动输出的运动/力传递关系,并提出了局部运动/力传递性能指标,评估了其在指定工作空间下的全局运动/力传递性能;然后,借助空间模型法,得到了索并联机器人在参数设计空间的性能图谱,并基于参数设计空间的性能图谱,对索并联机器人进行了尺度综合,以得到优化后的尺寸参数;最后,采用了平面3自由度索并联机构的试验样机,对运动学可达工作空间进行了试验验证,试验了得到了优化尺寸参数下的运动可达工作空间。研究结果表明:利用尺度综合方法优化后的机构允许姿态角达到|θ|≤60°的工作空间,占总工作空间的95.1%,可达工作空间提高了29.4%;优化后机构姿态角达到|θ|≤80°的工作空间,占总工作空间的67.3%,可达工作空间提高了81.3%;优化后允许机构姿态角达到|θ|=80°的工作空间,占总工作空间的14.5%,可达工作空间提高了172%。因此,对运动/力传递性能尺寸参数进行优化,可避免索并联机器人工作空间内的奇异位形,满足绳索单向力传递的特性要求,可在索并联机器人设计中作为尺度综合的依据。

The utilization of cable-driven parallel robots employing flexible cables instead of traditional rigid links for controlling the end-effector has found extensive applications in various fields such as place and pick,rehabilitation.Firstly,the screw theory was utilized to establish the motion/force transmission relationship between the actuator inputs and motion outputs of the cable-driven parallel robot,and the local motion/force transmission performance was determined.Secondly,the global motion/force transmission performance within a given workspace was evaluated.Then,by employing the optimal design space to conduct dimensional synthesis,the atlas of performance of cable-driven parallel robots were obtained.Based on the atlas of performance of cable-driven parallel robots,the dimensional parameters of the robots were optimized.Finally,a prototype of a planar 3-DOF cable-driven parallel mechanism was used to conduct kinematic reachable workspace verification experiments with optimized dimensional parameters.The experimental results show that,after optimization using the proposed dimensional synthesis method,the workspace of the mechanism allows the orientation angles|θ|≤60°accounting for 95.1%of the total workspace,it is an increase of 29.4%compared to the kinematic reachable workspace before optimization;the workspace of the mechanism that allows the orientation angles|θ|≤80°accounting for 67.3%of the total workspace,it is an increase of 81.3%compared to the kinematic reachable workspace before optimization;the workspace of the mechanism that allows the orientation angles|θ|=80°accounting for 14.5%of the total workspace,it is an increase of 172%compared to the kinematic reachable workspace before optimization.Therefore,optimizing the motion/force transmission performance enables cable-driven parallel robots to avoid singular configurations within the workspace and the unilateral force transmission property of the cables is considered.This optimized performance can be a reference for dimensional synthesis in the design of cable-driven parallel robots.