Multi-mode Subsea Manipulator Arm with Magnetic Position Feedback
Solution Overview
Problem
Existing manipulator arms for subsea applications face challenges in controlling velocity and position accurately due to mechanical connection failures, high cost, and complexity in SC mode, and simplicity and reliability issues in rate mode, particularly with mechanical sensors and hydraulic servo valves.
Innovation Solution
A multi-mode manipulator arm and drive system that incorporates rate mode selector switches, a spatially correspondent controller, mode selector device, local and remote control computers, and proportional flow directional control valves, allowing seamless switching between rate and SC modes, with position feedback and reduced reliance on mechanical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SC mode is used to achieve precise position and velocity control, then measurement precision and control accuracy are improved, but device complexity and cost increase due to mechanical sensors and hydraulic servo valves
Solution Approach 1:
The patent replaces mechanical connection sensors with magnetic field-based sensors that detect position and velocity without physical contact. This eliminates mechanical wear and failure points while maintaining measurement precision, directly resolving the contradiction between accuracy and complexity.
Solution Approach 2:
The patent uses magnetic field coupling through the arm wall to transmit position and velocity information without mechanical penetration seals. This hydraulic-free approach eliminates the complex mechanical connection seals required in traditional SC mode systems, reducing device complexity while preserving control accuracy.
2Device complexity
If rate mode is used to reduce complexity and cost, then device complexity is reduced, but control precision and velocity control capability are lost
Solution Approach 1:
The patent incorporates magnetic field sensors that provide continuous feedback on arm position and velocity to the control system. This feedback enables the simplified rate mode hardware to achieve SC-mode level control precision by continuously monitoring and adjusting based on actual position and velocity measurements.
Solution Approach 2:
The patent creates a control system that can operate in both rate mode and SC mode using the same hardware platform. The magnetic field sensors and control electronics support both operational modes, providing versatility without requiring separate complex systems for each mode.
3Loss of information
If mechanical connection seals are used in SC mode, then position feedback is achieved, but reliability decreases due to seal failures from mechanical wear
Solution Approach 1:
The patent replaces mechanical connection seals with magnetic field coupling that penetrates the arm wall without mechanical contact. This eliminates wear and failure points while maintaining reliable position feedback transmission, directly resolving the reliability issue with mechanical seals.
Solution Approach 2:
The patent uses magnetic fields as an intermediary to transmit position and velocity information across the arm wall without physical penetration. This magnetic coupling mechanism provides reliable information transfer without the mechanical wear and failure associated with traditional penetration seals.
4Speed
If hydraulic servo valves are used for velocity control, then velocity precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces hydraulic servo valves with electronically controlled proportional valves that respond to electrical signals for velocity control. This substitution maintains velocity precision while eliminating the complexity and cost of hydraulic servo systems.
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
The system provides a cost-effective, reliable, and flexible control mechanism that maintains operation even if position feedback sensors fail, with reduced complexity and increased longevity, enabling variable velocity and position control without mechanical connections, enhancing both operational simplicity and reliability.
Implementation Method 1
a proportional control solenoid configured to modulate the flow of hydraulic fluid in response to an error correction signal and a manipulator actuation signal
Implementation Method 2
a hydraulic piston configured to move the arm segment in response to the directional control valve
Data Source
AI summary
The present invention relates to a manipulator arm and drive system that can be operated in multiple modes, including an on or off mode, referred to herein as a “rate mode” or a spatially correspondent (“SC”) mode. The multi-mode manipulator arm and drive system of the present invention can be hydraulically operated subsea.