Cable Robot Coating System for Ship Hulls
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Solution Overview
Problem
Current painting technologies for large vertical surfaces, such as ship hulls, are inefficient and risky due to reliance on scaffolding, which is costly and time-consuming, and prone to overspray and equipment failure, especially when using two-cable suspension systems that can lead to swinging and breakage.
Innovation Solution
A mobile platform suspended by four controlled cables with Mecanum wheels and magnetic bases, allowing for precise positioning and movement on vertical or horizontal surfaces, using servo motors and ultra-high molecular weight polyethylene cables, with a magnetic brake to minimize coating loss and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two-cable suspension system is used, then device complexity is reduced, but reliability deteriorates due to swinging and cable breakage risk
Solution Approach 1:
The patent transitions from a symmetric two-cable suspension system to an asymmetric four-cable configuration where cables are positioned at different locations (two front cables and two rear cables). This asymmetric arrangement provides redundant support paths, preventing single-point failure and eliminating the swinging instability that plagues two-cable systems, thereby resolving the reliability issue while maintaining manageable complexity.
Solution Approach 2:
The four-cable system inherently provides a cushioning effect against failure by creating redundant load paths. If one cable fails or experiences excessive tension, the other three cables can redistribute the load, preventing catastrophic system failure. This beforehand cushioning approach directly addresses the reliability concern about cable breakage consequences.
2Reliability
If scaffolding is used for access, then worker safety is improved, but productivity deteriorates due to installation time and cost
Solution Approach 1:
The patent replaces the traditional mechanical scaffolding system with a cable-suspended robotic platform. Instead of using a rigid mechanical support structure (scaffolding), the system uses flexible cable suspension combined with active control mechanisms to achieve stable positioning. This substitution eliminates the time-consuming scaffolding installation and removal processes while maintaining worker safety through the controlled robotic platform.
Solution Approach 2:
The system transitions from static scaffolding to a dynamic cable-suspended platform that can be actively controlled and repositioned. The robotic platform can adjust its position, orientation, and movement speed dynamically during the painting process, enabling continuous operation without the interruptions required by fixed scaffolding setups, thereby improving productivity while maintaining safety.
3Productivity
If painting speed is increased, then productivity is improved, but manufacturing precision deteriorates due to overspray at movement inversion
Solution Approach 1:
The robotic painting system incorporates feedback control mechanisms that continuously monitor the platform's position, speed, and acceleration. The control system adjusts the painting parameters (such as spray rate, gun positioning, and movement speed) in real-time based on feedback from sensors and encoders. This feedback loop enables the system to maintain precise paint application even during movement inversions and direction changes, preventing overspray while sustaining high productivity.
Solution Approach 2:
The system employs periodic acceleration and deceleration patterns that are synchronized with the painting cycle. By anticipating direction changes and implementing controlled periodic motion profiles, the system can maintain optimal painting speed while preventing overspray at inversion points. The periodic action is coordinated with the paint application rate to ensure precision is maintained during speed variations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient, uniform, and controlled paint application over large surfaces, reducing the need for scaffolding, minimizing worker exposure to danger, and ensuring consistent paint thickness while preventing waste, with the ability to adjust application speed and angle for optimal coverage.
Implementation Method 1
The mobile platform (3) is positioned by cables, with its suspension system placed on free Mecanum wheels that behave like spheres. The wheels are affixed to vertical or horizontal walls by a magnetic base (23) that is located on the wheels.
Implementation Method 2
In the winding section, the proposed system contains servo motors in a synchronous serial network, ultra molecular weight polyethylene cables, magnetic bases, and a magnetic brake.
Data Source
AI summary
The present invention refers to an automated painting system on oil ships, being executed by a mobile platform and an oscillating arm. The assembly only works due to the control of cables, winders and wheels. This approach is aimed at painting large vertical walls. The painting deck suspension uses four cables, each connected to a pivot on the mobile platform, and two fixed pivots plus four winders. The winders contain a servo motor in a synchronous serial network. The cables are made of reduced-weight polyethylene. Each cable is connected exclusively to one winder. Suspension is achieved with the aid of two adapted cranes and initialization through the addition of a giraffe-type crane.