Using NI LabVIEW and CAN to Control an Underwater Remotely Operated Vehicle
"Component commonality between software and hardware reduces costs, and we forward those savings to the customer per nonrecurring engineering (NRE) reduction."
- Martin Wareham,
Sub-Atlantic Ltd.
The Challenge:
Designing, developing, and building hardware and software to control a remotely operated vehicle (ROV) in real time and relay diagnostic information regarding ROV health back to the ROV pilot in a simple and intuitive manner.
The Solution:
Using NI LabVIEW software, an NI PCI CAN board, a PC, and other in-house electronic subassemblies and firmware to design, produce, and deliver subCAN – an advanced, reliable, and scalable small- to medium-sized ROV control system – while gaining significant time and financial savings.
Author(s):
Martin Wareham -
Sub-Atlantic Ltd.
As part of Triton Group Holdings, our engineers and scientists at Sub-Atlantic Ltd. are world leaders in the design and production of small- to medium-sized underwater ROVs.
We created a powerful 19 in. rack-mount PC that runs the subCAN application and provides the ROV pilot with a simple and intuitive graphical user interface on a touch screen.
The PC also houses the PCI CAN board, which interfaces to a variety of pieces of surface equipment that the ROV pilot requires to control the ROV and tether management system (TMS).
Reducing Costs with Flexible Real-Time Control Systems, Component Commonality
Controller area network (CAN) bus technology provides the control system with a flexible and relatively fast communication mechanism with minimal software and firmware overheads.
In addition, we use multidrop CAN networks as part of the subCAN control system so the system design engineer can scale the control system from one ROV to another without having to redesign any hardware or firmware from scratch. Software engineers can do the same with the inherent modularity of LabVIEW software and subCAN hardware and firmware.
Component commonality between software and hardware reduces costs, and we forward those savings to the customer per nonrecurring engineering (NRE) reduction. This commonality also minimises any spare hardware components that operators may carry on a boat or oil rig.
Ensuring Safety with Subsea Electronics
The subCAN distributed control system features subsea electronics that we design in house. Because we design these subsea electronics to operate under any extreme conditions, subCAN can handle common harsh underwater environment challenges such as water ingress.
Overvoltage and overcurrent protection on subCAN I/O and communication channels prevents electronic component damage. These subsea electronic subassemblies work with various communication interfaces such as RS232, RS485, Ethernet, and CAN.
The vessels that transport the ROVs around the ocean floor cost hundreds of thousands of pounds to run daily. The protection mechanisms, overall reliability, and robust communication protocols of subCAN, along with experienced electric, software, and system design engineers, are key to its continued success.
Generating High-Quality Diagnostic Feedback
SubCAN features increased sensory feedback and diagnostic information, compared to other small- to medium-sized ROVs, that is displayed on the LabVIEW GUI touch screen, providing the ROV pilot with as much information as possible concerning the status of the ROV and the subCAN control system.
The ROV can move up to 6,000 m away from the ROV pilot on the support vessel, which increases the need for high-quality sensory feedback to control, navigate, and plan scheduled maintenance on the ROV.
The ROVs are the sole mechanism to transport complex tools and sensors, which have become more popular in the last decade, to the underwater work site to carry out various underwater tasks. The multiple variations of these tools must interface with a flexible and configurable ROV control system. Several tools and sensors that can connect to the subCAN-controlled ROV including the following:
Various electrical and hydraulic manipulators, such as mechanical arms, so the ROV pilot can pick up, hold, and manoeuvre underwater objects
- Torque tools for turning underwater valves on manifolds with a controlled amount of torque
- Skids that can attach to the underside of the ROV to carry out various tasks such as surveying pipeline, deploying cable length underwater, and pumping and flushing fluids in and out of an underwater manifold or pipeline
- High-definition video cameras with crisp, movie-like video images
- High-resolution acoustic sonars that feature quality similar to that of underwater video cameras because underwater visibility can be a problem for normal video cameras in low light
- Fibre-optic gyros and inertial sensors used for highly accurate underwater navigation
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