Underwater Inspection Arm Control Without Pipeline Contact
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Solution Overview
Problem
Conventional remotely operated underwater vehicles (ROVs) risk damaging subsea structures due to the force applied by their mass during inspection and cleaning, and are limited in the weight of devices they can carry, hindering the quality of underwater work.
Innovation Solution
An underwater mobile inspection apparatus that cruises alongside subsea structures without contact, using a movable arm and inspection tool unit controlled by a controller to maintain a predetermined positional relationship, allowing for precise inspection and reducing the risk of damage by avoiding direct force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the remotely operated underwater vehicle runs on the subsea structure via casters to inspect and clean it, then the operator can control the vehicle to move underwater in a flexible manner, but force based on the mass of the vehicle is applied to the subsea structure causing stress and potential damage
Solution Approach 1:
The patent introduces a cable as an intermediary element that transmits control forces from the surface vessel to the underwater vehicle. The vehicle is pulled by the cable rather than moving independently on casters, which eliminates direct contact forces between the vehicle mass and the subsea structure, thereby preventing stress and damage while maintaining operational control
2Productivity
If devices and manipulators are loaded onto the vehicle for inspection and cleaning work, then the quality of various work can be improved, but the loaded mass onto the vehicle increases which is limited by the force applied to the subsea structure
Solution Approach 1:
By using the cable-pulled configuration, the patent decouples the vehicle's operational capability from the structural load on the subsea infrastructure. This allows heavier devices and manipulators to be mounted on the vehicle without increasing the force applied to the subsea structure, as the vehicle is supported by the cable tension from the surface vessel rather than relying on caster contact with the structure
Solution Approach 2:
The cable system acts as a counterbalancing mechanism, where the tension in the cable compensates for the weight of the vehicle and its loaded equipment. This allows the vehicle to carry heavier inspection and cleaning devices without exceeding force limits on the subsea structure, as the cable bears the load rather than the structure itself
Data Source
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Figure 3A~3B
AI summary
An object is to prevent damage to an inspection object such as a subsea structure, the damage being due to receiving force based on the mass of a cruising body, and to improve the quality of various work, including an inspection of the inspection object. An underwater mobile inspection apparatus 11 is capable of inspecting a subsea pipeline (inspection object) 13 while cruising. The underwater mobile inspection apparatus 11 includes: a cruising body 14 configured to submerge under water and cruise along the inspection object in such a manner as not to come into contact with the subsea pipeline 13; a first movable arm 16 provided on the cruising body 14; an inspection tool unit 17 for use in inspecting the subsea pipeline 13, the inspection tool unit 17 being provided on the first movable arm 16; and a controller configured to, when the cruising body 14 cruises along the subsea pipeline 13 in such a manner as not to come into contact with the subsea pipeline 13, operate the first movable arm 16 to move the inspection tool unit 17, such that a positional relationship of the inspection tool unit 17 with the subsea pipeline 13 becomes a predetermined target positional relationship.