Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Comparative analysis of different modeling approaches on cable-suspended parallel robots
Submission Author:
Fabiola da Silva Rosa , SC
Co-Authors:
Fabiola da Silva Rosa, Estevan Hideki Murai, Henrique Simas
Presenter: Fabiola da Silva Rosa
doi://10.26678/ABCM.COBEM2021.COB2021-1576
Abstract
Cable-driven parallel manipulators are a robot class where cables connect the fixed platform and the moving platform. These cables increase or decrease their length to change the robot position. The cable-driven parallel robots have some advantages compared to rigid parallel robots. Cable robots have reduced mass and inertia, their payload to robot weight ratio is larger, they can achieve higher dynamic performances, they have a larger workspace, the manufacturing and maintenance costs are reduced, they are easier to assembly and disassembly, and they have superior modularity and reconfigurability. Despite these advantages, some factors complicate cable robot modeling and control. Since the cable is flexible, and it must always be under a tension force, the control algorithm has to consider the cable tension in every robot posture. Besides, the control algorithm needs to predict and avoid collisions. These collisions can occur among cables, between cables and the environment, between cables and other robot rigid structures, and between the platform and the environment. Also, the position precision and trajectory tracking are limited. Cable-suspended parallel robots are a cable robot subclass. In this case, there is no cable under the moving platform, and the gravity is considered a constraint, similar to a cable under the platform. Comparing suspended and non-suspended cable robots, suspended robots have fewer cables and, consequently, fewer collisions possibilities. Nevertheless, since there is no cable under the platform, it is more complex to maintain the cables tension in every robot posture. Besides that, precise tracking trajectory control is more complicated to achieve. Moreover, suspended robots may become unstable, easy to vibrate, and even out of control under external disturbances. The robot precision is related to its modeling. Thus, the cable model is one of the most critical considerations in cable robot modeling. In general, a complex model is a precise model. However, if the model is too complicated, it is required a substantial computational time to solve it. In the literature, four different cable modelling was found: inextensible and massless cable, inextensible cable with non-negligible mass, elastic and massless cable and elastic cable with non-negligible mass. The main goal of this work is to present and compare these four different cable modellings in order to help designers on choosing the most suitable modelling regarding each cable robot case.
Keywords
cable-suspended parallel robots, comparative analysis, modeling
