Redundancy resolution of 9-DOF machine through synthesized global and local performance indices

Abstract

The 9-degrees-of-freedom (DOF) machine is used to lay the rotating mold driven by the positioner. In order to reduce the 9-DOF machine to a 6-DOF non-redundant structure, this paper proposes a redundancy resolution method based on synthesized global and local performance indices. Since the number of non-redundant machine types is enormous, all non-redundant machines are divided into six classes depending on the redundant joints, called axis assignment schemes. After defining the global and the local performance indices of the non-redundant machine, the redundancy resolution method is proposed. It consists of three parts: Firstly, refine the machine types of each axis assignment scheme based on the average global indices. Then, select the best axis assignment scheme by comparing the scheme’s local indices for a given mold. Finally, optimize the non-redundant machine type contained in the optimal scheme with the objective of superior local indices and continuous positioner rotation space. In the experiment, using the air-inlet as an example, two motion planning methods gave different motion trajectories for the 7-DOF layup system. The effectiveness of the proposed method was verified analytically by comparing the joint motion and fiber placement speed of the optimal machine type with other types.