Modeling and Analysis of the Stiffness Distribution of Host-Parasite Robots

The stiffness distribution (SD) of robot has a great influence on the robot pose accuracy, but the calculation efficiency and accuracy of stiffness distribution are still low. This study presents a finite element fitting method with an extremely small number of computational cells. It was developed based on experimental results of robot stiffness. This method can be employed to establish single- and multi-source fitted SD (FSD) (S-FSD and M-FSD) models for host-parasite (H-P) robots. The computational efficiency and correctness of the FSD models were verified by case studies. The configurations of six evolutionary mechanisms of an H-P robot were subjected to an SD analysis. A comparison of the six configurations shows that adding parasitic branched chains can improve the SD of the H-P robot to varying degrees. In particular, the most notable improvement was for H-P mechanism. Specifically, by averaging the stiffness of all positions, the average-stiffnesses of H-P mechanism in the x-, y-, and z-directions were 104.10%, 1427.78%, and 1101.62% of those of the host mechanism, respectively. In the SD diagram, the medium- and high-stiffness regions of mechanism F are large and distributed in a banded pattern between the highest pose point and the furthest pose point, whereas its low-stiffness region is small and concentrated near the nearest pose point.