Climbing parallel robot: a computational and experimental study of its performance around structural nodes

This paper presents a study of the kinematics and dynamics performance of a climbing parallel robot (CPR) to avoid nodes on structural frames. To avoid a structural node, a CPR can acquire some determined postures. A series of postures can be combined to generate the convenient movements to climb along the structural node. The postures of a CPR must be studied to detect its feasibility, because the postures can drive the robot near its singular configurations. Also, the forces originated in the actuators to evade the structural nodes are evaluated. Therefore, the goal of this paper is to show that a Stewart-Gough (S-G) parallel platform can be used as a climbing robot, because a CPR can avoid structural nodes easily and elegantly, in contrast with other types of robots. To support the simulation results presented in the first part of this paper, an experimental testbed has been developed to study the dynamic performance of the CPR prototype around a structural node. The results obtained are very interesting, and show that an industrial potential to use the parallel S-G robot as a climbing robot exists. Index Terms--Climbing robots, dynamics, parallel robots, singularities.