Robotics Research Journal (RRJ)

Research Article

The New Form of a Mathematical Model of a Cable suspended Parallel Robot Caused by Using of a New Winch Form

Mirjana M. Filipovic¹and Ljubinko B. Kevac²

¹Mihailo Pupin Institute, University of Belgrade, Volgina 15, 11000 Belgrade, Serbia.

²Innovation center of School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11000 Belgrade, Serbia.

Submitted: September 3, 2019; Revised: October 3, 2019; Accepted: November 11, 2019

Abstract

This paper presents novel results, which were initially developed based on wide analysis of well-known winch constructions, which were used as main parts of actuating subsystems of Cable suspended Parallel Robots (CPR) systems. The motivation of this work was the need to define and recognize dynamic characteristics of the winch such as radius and length of cable winding/unwinding, since it was shown that these variables highly affect dynamic response of CPR system. It has been proven that “jumpy” changes of these two variables generate oscillatory and unstable behavior of the system. It gets even more complicated when the CPR system has more of these winches and coupling of their dynamics occurs. If cable winding/unwinding radius and length have “jumpy” behavior, there is no control algorithm would stabilize the system. Un-modeled dynamics can highly affect oscillatory behavior and instability of the system. Because of these reasons, the new construction of the Cable suspended Parallel Robot that is using winches for performing single - row Radial Multi-layered smooth cable winding/unwinding (CPRRM system), and its mathematical model was defined and presented. Generally, it can be said that the analysis of the geometry of the selected mechanism is the first step, which is a very important step to establish the structural stability of the CPR systems. In order to discover all characteristics, geometry analysis of all system’s components has to be first done, which as result, implies the possibility of the realization of the desired camera motion. The next step is to define a new form of kinematic and dynamic model. Then novel software package CPRRMSOFT (in MATLAB) was generated. This program package was used for the validation of the theoretical contributions. Also, it was used to check and choose all the parameters of the system and parameters of its components, and possible selection of the control structure. Validity of the obtained theoretical contributions has been illustrated in this paper through one case study. The whole procedure is iterative and repeatable. This is the procedure which leads toward implementation of complex CPR system.

Keywords

Winding/Unwinding; Winch, Kinematics; Dynamics; Coupling.

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