Most driving torques in serial industrial robots are used to overcome the weight of the robot. Although actuators account for a large proportion of the total mass of a robot, they have yet to become a positive factor that enables the robot to achieve gravity balance. This study presents a host–parasite structure to reconstruct the distribution of actuators and achieve gravity balance in robots. First, based on the characteristics of tree–rattan mechanisms, a method for calculating the degrees of freedom and a symbolic representation method for the distribution of branched chains are formulated for host–parasite mechanisms. Second, a configuration analysis and optimization method for host–parasite structure-based robots and a robot prototype are presented. Finally, four host–parasite mechanisms/robots (A, B, C, and D) are compared. The results are as follows. If more parasitic branched chains are added to the yz plane, the loads along axes 2 and 3 become more balanced, which significantly increases the stiffnesses of the mechanism in the y- and z-directions (Ky and Kz , respectively). If the additional branched chains are closer to the site of maximum deformation, the stiffness of the mechanism in the z-direction (Kz ) increases more significantly. Of the four mechanisms, mechanism D has the best overall performance. The joint torques of mechanism D along axes 2 and 3 are lower than those of mechanism A by 99.78% and 99.18%, respectively. In addition, Kx , Ky , and Kz of mechanism D are 100.56%, 336.19%, and 385.02% of those of mechanism A, respectively. Moreover, the first-order natural frequency of mechanism D is 135.94% of that of mechanism A. Host–parasitic structure is conducive to improving the performance of industrial robots.

中文翻译：

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工业机器人宿主-寄生虫结构分析

串行工业机器人中的大部分驱动扭矩用于克服机器人的重量。虽然执行器在机器人的总质量中占很大比例，但尚未成为使机器人实现重力平衡的积极因素。本研究提出了一种宿主 - 寄生虫结构，以重建执行器的分布并实现机器人的重力平衡。首先，根据树-藤机制的特点，提出了寄主-寄生虫机制的自由度计算方法和支链分布的符号表示方法。其次，提出了一种基于宿主-寄生虫结构的机器人和机器人原型的配置分析和优化方法。最后，比较了四种宿主-寄生虫机制/机器人（A、B、C 和 D）。结果如下。如果向 yz 平面添加更多寄生支链，则沿轴 2 和 3 的载荷变得更加平衡，这会显着增加机构在 y 和 z 方向（分别为 Ky 和 Kz ）的刚度。如果附加支链更接近最大变形位置，则机构在 z 方向 (Kz ) 上的刚度增加得更显着。在四种机制中，机制 D 的综合性能最好。机构 D 沿轴 2 和 3 的关节扭矩分别比机构 A 低 99.78% 和 99.18%。此外，机制 D 的 Kx 、Ky 和 Kz 分别是机制 A 的 100.56%、336.19% 和 385.02%。此外，机构 D 的一阶固有频率是机构 A 的 135.94%。