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There are many standards and requirements for certification of a shipboard and offshore crane. This lifting appliance must handle cargo, the monopile, within the vessel while at sea and move it outside the vessel for placement in the seabed.

One certification needed is compliance to DNV GL rule 2.2, “Lifting appliances," and there are many parts, components and systems covered by this standard. Beyond load-carrying structural members and other mechanical components of the lifting appliance, there were many electrical and control parts to comply with. This included power systems for hoisting, brakes and braking systems, safety equipment, protection against fire, control and monitoring systems and electrical installation.

Design examination was a big part of the certification activities. This included strength and suitability of purpose; surveys to confirm compliance with the approved drawings, compliance with regulation and standards; good workmanship and functional testing and load testing.

Compliance with EN ISO 13849-2, “Safety of machinery—Safety-related parts of control systems,” is also a requirement. This standard covers general design principles and validation of safety-related parts of control systems. This includes mechanical, pneumatic, hydraulic and electrical technology. It also describes typical safety functions, required performance levels and validation by analysis and testing of such. Hardware control

We used the CompactRIO platform to overcome many of the engineering challenges we faced. The CompactRIO system controls the hydraulic valves and the hydraulic power supply. It also monitors the position of the cylinders, accumulator pressure, angle of the tool, reservoir level and battery level. Additionally, the system controls the warning signals and relays the information to the operator through a radio transmitter/receiver module.

The CompactRIO system also helps to implement safety standards. For instance, when there is a communication error in the radio signal, it ensures all the outputs fail safely. Similarly, the system sends a watchdog signal to a safety relay. The tool fails safely in the case of a power outage. The CompactRIO interfaces with the other elements of the upending-tool design, as well.

Early in the design process, we considered several alternative solutions to the CompactRIO. The first solution we considered used relay logic. However, this limited functionality and scope for future development. Alternatively, we reviewed using a programmable logic controller (PLC) or embedded hardware, but they lacked significant advantages compared to developing a solution with LabView and CompactRIO.

We used several configurable and interchangeable modules with the CompactRIO chassis—cRIO-9075—which worked well and can be expanded in the future. These modules included a NI-9425 digital input module, NI-9476 digital output module, NI-9203 analog input module and NI-9263 analog output module. Modular software design

The LabView development environment significantly improved the design process in many ways. Its modular software design provided seamless integration between software written by multiple developers. Intuitive debugging made it is easier and faster to pinpoint errors when writing the software.

The code is easy to reuse across multiple projects by leveraging subVIs (virtual instruments) and libraries. This will also reduce the engineering time for future projects, and the numerous libraries allow fast and efficient programming by using pre-existing functions.

The drag-and-drop interface and easy-to-make graphical user interface also reduced programming time. Compatibility with other programming languages enabled the developers to program in specialized languages and use LabView to interface them all together.

We used the standard service program from National Instrument to help us to complete online training and reduce training costs. National Instruments also has specialized support engineers to help to resolve any technical issues with hardware or software. We could also simulate the hardware.

In addition to improving the design process, using CompactRIO alongside LabView helped us to add important features to the project that we could otherwise not implement. An important safety feature was to use the CompactRIO field-programmable gate array (FPGA) as a watchdog to monitor the safety relay. We also used the FPGA to generate pulse-width-modulation signals for the locking latch and pivot-cylinder hydraulic control valves to provide smoother system operation.

Through the use of shared variables, we could remotely monitor certain parameters. We also created personalized interfaces for different clearance levels such as operator, service engineer, software engineer and diagnostics checks. A new iteration

The main advantages of the upending tool, compared to previous solutions, are independence from external power sources and the fact it removes the need for human intervention during connection and disconnection. With no slings or service lines to manage, the connection point can overhang the vessel deck and the overall lifting and upending time can be dramatically reduced. The key benefit of this to installation operations is more efficient and safer use of the vessel’s heavy lift crane.

Once the pile is in place, the tool is returned to the deck, parked and plugged into the its power supply to charge the hydraulic accumulators and battery while the crane is freed to carry out other operations, such as hammering. This solution is simpler to operate and more independent, thanks to the radio control unit replacing signal lines. Using wireless data transfer, however, is less robust than physically connected cables. The CompactRIO ensures that, in the event of a communication error, there are no unexpected failures.

The tools have now installed all 116 monopiles on the wind farm site with no reported downtime, proving the reliability and robustness of the design. The upending tools are now available for use in future wind-farm projects. ALSO READ: Use distributed control to offload PLCs and PACs