Parameter Optimization for the Driving System of a 5 Degrees-of-Freedom Parallel Machining Robot With Planar Kinematic Chains
Parameter Optimization for the Driving System of a 5 Degrees-of-Freedom Parallel Machining Robot With Planar Kinematic Chains
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DOI：
10.1115/1.4043291
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发表时间：
2019-08
期刊：
影响因子：
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通讯作者：
Zenghui Xie;F. Xie;Xinjun Liu;Jinsong Wang;Xu Shen
中科院分区：
文献类型：
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作者：
Zenghui Xie;F. Xie;Xinjun Liu;Jinsong Wang;Xu Shen
驱动系统参数优化是提高机器人加速能力、承载能力和运行稳定性等动态性能的重要途径。为了获得更好的动态性能，通常使用大功率和高成本的电机。但这导致了资源的浪费。要使机器人既满足规定的要求，又避免设计过于保守，是一个困难的问题。对于并联加工机器人，由于封闭运动链的耦合特性，这个问题更具挑战性。提出了一种具有平面运动链的五自由度并联加工机器人，并基于虚功原理建立了其动力学模型。在此基础上，提出了一种适合于5自由度加工机器人的DSPO方法。这些轨迹下的电机输出和候选电机参数以综合图的形式呈现。结合电机选型准则，推导出了可行的电机和可用的减速比范围。为了优化减速比，提出了一种基于电机输出转矩变化程度的动态指标来评价驱动系统的运行稳定性。在此基础上，通过最小化该指标得到最优减速比，以提高加工机器人的稳定性。基于该方法，实现了5自由度并联加工机器人的DSPO，生成了最优驱动单元。该方法可用于其他5自由度并联机器人的DSPO。
Driving system parameter optimization (DSPO) is an important approach to improve robots' dynamic performances such as acceleration capacity, load carrying capacity, and operation stability. To achieve better dynamic performance, motors with high power and high cost are generally used. But this leads to a waste of resources. It is difficult to simultaneously make the robots satisfy the prescribed requirements and avoid over conservative design. This issue is much more challenging for parallel machining robots due to the coupling characteristics of the closed kinematic chains. In this paper, a 5 degrees-of-freedom (DoF) parallel machining robot with planar kinematic chains is presented, and its dynamic model is established based on the virtual work principle. Then, a DSPO method for 5-DoF machining robots is proposed by considering the classical machining trajectories that can reflect the robots' performance requirements. The motor output under these trajectories and candidate motor parameters are presented in a comprehensive graph. Combined with motor selection criteria, the feasible motors and usable reduction ratio range are derived. To optimize the reduction ratio, a dynamic index is proposed based on the variance degree of the motor output torque to evaluate driving system's operational stability. On this basis, the optimal reduction ratio is obtained by minimizing this index to improve the stability of machining robots. Based on the proposed method, the DSPO for the 5-DoF parallel machining robot is implemented, and the optimal driving units are generated. The proposed method can be used for the DSPO of other 5-DoF parallel machining robots.