Abstract
For the motion coordination problem between the underwater vehicle and manipulator of the underwater vehicle–manipulator system, a new redundancy resolution method is proposed and investigated. The proposed method mainly has two parts: a fuzzy logic part and a multitasks weighted gradient projection method part. The fuzzy logic part is used to decide the weight factors of the motion distribute matrix and the priorities of all the secondary objectives, while the multitasks weighted gradient projection method part is used to handle the secondary objectives with the weight factors and priorities decided by the fuzzy logic part. Moreover, a new secondary objective is proposed to optimize underwater vehicle–manipulator system’s attitude, which takes the payload into consideration. Finally, the effectiveness of the proposed redundancy resolution is verified through some comparative simulations.
Highlights
In recent few decades, underwater vehicle–manipulator systems (UVMS) have been widely used in the underwater working applications due to their good capabilities in the deep ocean, especially the area where human driver can hardly arrive.[1,2,3] Generally speaking, the UVMS consists of an underwater vehicle and one or more manipulators
1. give a new UVMS attitude optimization index design, which takes the payload into consideration; 2. propose a new multitasks weighted gradient projection method (GPM) with fuzzy logic (FL) using the newly given index and verify its effectiveness through three comparative simulations
The optimal effect of weighted pseudoinverse method equation (13) is weaker compared with GPM, but it has an attractive nature as the end-effector stops moving, the internal movement of UVMS will vanish
Summary
Underwater vehicle–manipulator systems (UVMS) have been widely used in the underwater working applications due to their good capabilities in the deep ocean, especially the area where human driver can hardly arrive.[1,2,3] Generally speaking, the UVMS consists of an underwater vehicle and one or more manipulators. The ROV and corresponding manipulator are controlled separately by the pilot during the tasks, or the ROV keeps station automatically while only the manipulator is manually controlled This operation mode is simple but sometimes inefficient because the inherent redundancy of UVMS is totally eliminated. To solve the abovementioned problem and improve the working efficient of UVMS, the position and orientation of UVMS’s end-effector can be directly commanded to perform the tasks This operation mode can effectively exploit the redundancy of UVMS and lead to more flexible working ability. The attitude of UVMS can be greatly affected if the payload is relatively large and no proper redundancy resolution is adopted To solve this problem, a novel redundancy resolution using a new designed secondary objective is proposed and investigated in this article. The proposed method combines the FL with multitasks weighted GPM and can effectively ensure the attitude of UVMS stable with the new proposed secondary objective
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