Dynamic Modeling and Simulation of Underwater Parallel Robot

Abstract

Working under water, the hydrodynamics can’t be ignored, and with the increase of the speed and acceleration of the underwater parallel manipulator, the weight of the fluid dynamics in the load also increases obviously. Therefore, the effects of fluid dynamic parameters must be considered in the process of dynamic modeling the underwater parallel robot. Firstly, based on a typical Delta 3-degree-of-freedom parallel manipulator model, the dynamic model of underwater parallel robot is carried out. (1) Considering the buoyancy, distance between buoyancy and center of gravity, the part of the Delta 3-degree-of-freedom parallel manipulator dynamic model, which is just related to the gravity, is modified. (2) The fluid resistance which is related to the speed of the robot's active rods and the slaves are considered and added to the original 3-degree-of-freedom parallel manipulator dynamic model; (3) Considering the characteristics of the underwater unsteady moving object, the additional mass parameters are analyzed and added to modify the original dynamic model. Secondly, based on the 3-degree-of-freedom Delta parallel manipulator motion position inverse solution model and the modified dynamic model, the trajectory and mechanical properties of the underwater parallel robot are simulated. The difference between the trajectory of the parallel manipulator in the air and the underwater motion is analyzed and compared with the same driving conditions. And the mechanism why the difference is caused by the related fluid dynamic parameters, motion parameters and structural parameters are analyzed. The conclusions obtained in this paper have useful reference value for the design of underwater parallel robots.