Dynamics Modelling and Robust Passivity-Based Control of Cable-Suspended Parallel Robots in Fluidic Environment

Abstract

Cable-driven parallel robots (CDPRs) are specialized parallel robots where flexible cables are used for connecting the base platform (BP) to the moving platform (MP). In these robots, cables can be winded or unwinded using electrical motors, winches, and pullies to move the MP. Different applications are proposed for these robots mainly because of their low inertia relative to high load carrying capacity and large workspace. In this paper, the application of CDPRs in fluidic environments for underwater navigation and intervention is introduced. At first, kinematics and dynamics equations considering fluid forces, including buoyancy, drag, and added mass, are derived. Later, two controllers consisting of inverse dynamics (ID) and robust passivity-based (RPB) are implemented on a suspended CDPR. The effect of considering fluid forces in the ID controller command is investigated using simulation in MATLAB software. The results are analyzed to show the importance of considering these forces in robots' dynamics. Finally, some uncertainties are proposed in the robot and fluid parameters to study the efficiency of two controllers. The effectiveness of the RPB controller to tackle uncertainties in the robot and fluid parameters are declared.