Research on Autonomous Grasping Control of Underwater Manipulator Based on Visual Servo

Underwater positioning presents a challenging issue, because of the rapid attenuation of electronic magnetic waves, the disturbances and uncertainties in the environment. Conventional methods usually employed acoustic devices to localize Unmanned Underwater Vehicles (UUVs), which suffer from a slow refresh rate, low resolution, and are susceptible to the environmental noise. In addition, the complex terrain can also degrade the accuracy of the acoustic navigation systems. The applications of underwater positioning methods based on visual sensors are prevented by difficulties of acquiring the depth maps due to the sparse features, the changing illumination condition, and the scattering phenomenon. In the paper, a novel visual-based underwater positioning system is proposed based on a Light Detection and Ranging (LiDAR) camera and an inertial measurement unit. The LiDAR camera, benefiting from the laser scanning techniques, could simultaneously generate the associated depth maps. The inertial sensor would offer information about its altitudes. Through the fusion of the data from multiple sensors, the positions of the UUVs can be predicted. After that, the Bundle Adjustment (BA) method is used to recalculate the rotation matrix and the translation vector to improve the accuracy. The experiments are carried out in a tank to illustrate the effects and accuracy of the investigated method, in which the ultra-wideband (UWB) positioning system is used to provide reference trajectories. It is concluded that the developed positioning system is able to estimate the trajectory of UUVs accurately, whilst being stable and robust.

show abstract

“…Although there are some visual positioning systems using the artificial makers [ 22 , 23 ], the markers are required to be set out beforehand.…”

Section: Related Work In Underwater Visual Positioningmentioning

confidence: 99%

An Underwater Positioning System for UUVs Based on LiDAR Camera and Inertial Measurement Unit

Yang

Jia

2022

Sensors

View full text Add to dashboard Cite

show abstract

“…The results presented that the implementation of the markers did increase navigation performance. In addition to that, Zhang used the ArUco marker to estimate the position of the manipulator at a high rate of speed in underwater environments [25]. Experiments are carried out with the 7-function underwater hydraulic manipulator.…”

Section: Related Workmentioning

confidence: 99%

An Underwater Visual Navigation Method Based on Multiple ArUco Markers

Haroutunian

Murphy

et al. 2021

JMSE

View full text Add to dashboard Cite

Underwater navigation presents crucial issues because of the rapid attenuation of electronic magnetic waves. The conventional underwater navigation methods are achieved by acoustic equipment, such as the ultra-short-baseline localisation systems and Doppler velocity logs, etc. However, they suffer from low fresh rate, low bandwidth, environmental disturbance and high cost. In the paper, a novel underwater visual navigation is investigated based on the multiple ArUco markers. Unlike other underwater navigation approaches based on the artificial markers, the noise model of the pose estimation of a single marker and an optimal algorithm of the multiple markers are developed to increase the precision of the method. The experimental tests are conducted in the towing tank. The results show that the proposed method is able to localise the underwater vehicle accurately.

show abstract

“…Therefore, the precise control of the hydraulic underwater manipulator becomes urgent. Some high precision hydraulic valves are invented and some advanced control algorithms are developed 10,11 in the system, or some external high precision sensors are mounted on the manipulator 12 to improve the path accuracy or the automation capabilities of the manipulator. 13 In precise and automate control mode, the singularity avoidance of manipulator cannot be ignored, since the singularity is the inherent nature of mechanical structure, 14,15 which would make the manipulator lose the motion ability in some degrees of freedom.…”

Section: Introductionmentioning

confidence: 99%

A computation effective singularity avoidance method for the underwater manipulator with a non-spherical wrist

Gao

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part M:

View full text Add to dashboard Cite

In order to perform increasingly complex underwater tasks, we have designed a hydraulic underwater non-spherical wrist manipulator with a binocular vision system and a six-dimensional force sensor mounted behind the end-effector, which can improve the path accuracy and automation capabilities of the system. The system lays a foundation for the high precision and autonomous deep-sea operation and can improve its intelligence level. In this paper, we focus on solving the singularity avoidance problem of the hydraulic underwater manipulator for accurate control, and propose a computationally efficient singularity avoidance method to improve the path accuracy of the manipulator with the non-spherical wrist. Firstly, the singular configurations of the manipulator are analyzed. Secondly, the Jacobian is decomposed into sub-block matrices to obtain the singular factors according to the singular configurations. Thirdly, the singularities are avoided by the approximate damped reciprocal method. Theoretical analysis shows that the computation costs of the proposed method are only one-third to one-half of that of the traditional methods. The simulation results prove that the proposed method can largely improve the path accuracy of the manipulator with less computation costs, which shows that our method would have a certain significance in improving the precision and real-time response of deep-sea operations.

show abstract

Research on Autonomous Grasping Control of Underwater Manipulator Based on Visual Servo

Cited by 9 publications

References 8 publications

An Underwater Positioning System for UUVs Based on LiDAR Camera and Inertial Measurement Unit

An Underwater Positioning System for UUVs Based on LiDAR Camera and Inertial Measurement Unit

An Underwater Visual Navigation Method Based on Multiple ArUco Markers

A computation effective singularity avoidance method for the underwater manipulator with a non-spherical wrist

Contact Info

Product

Resources

About