On the real-time calculation of the forward kinematics of suspended cable-driven parallel robots

Description

This paper addresses the problem of the forward kinematics of cable-driven parallel robots (CDPR) having elastic or non elastic cables under the assumption that the cables are submitted to small changes in their lengths compared to an initial situation at which the pose is known, a situation that is typical of a real-time forward kinematics used for control purposes. We show that at the initial point it is necessary to have not only the pose but also the cable configuration, i.e. having the knowledge of which cables are under tension and that the result of the forward kinematics should be both the pose and the cable configuration after the change in cable lengths. We exhibit a first algorithm that allows one to determine all possible final poses and cable configurations. Then a second algorithm is proposed to determine all possible cable configurations also during the coiling process which is an important point as the CDPR state, including the cable tensions, may drastically change at this point. The last algorithm assumes a model of the coiling process and is able to determine the unique final pose and cable configuration. These algorithms provide safer real-time forward kinematics which will improve the CDPR control

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