Fig. 1: The booms of the ship-to-shore container cranes are up to 100m long
Liebherr, a world-wide leading manufacturer of construction machinery, recently started using the visualization system VisiWin developed by INOSOFT for diagnostic and maintenance purposes for their ship-to-shore container cranes. A 3D model generated by the powerful software allows to display the whole facility so that operators can quickly locate disturbances. In addition, trend charts and statistical charts based on an analysis of the operating data can be displayed. Another unique selling proposition of VisiWin is its open API for custom developments. Engineers at Liebherr-Components Biberach GmbH used VisiWin to develop a framework for the quick adaptation of the visualization to different crane types.
Fig. 2: Main view of the crane visualization software
The cost-effectiveness of ship-to-shore container cranes is basically affected by two factors: First, by performance – i.e. lifting power and speed – and second, by idle time, which must be reduced to a minimum. This is particularly important for the huge ship-to-shore container cranes, such as those manufactured by Liebherr Container Cranes Ltd. in Ireland. To face the challenges of just-in-time logistics, the loading and unloading units must be available around the clock. If goods are not loaded in due time, port operators run the risk of high contractual penalties. In addition, with regard to their technical complexity and size (crane booms are up to 100m long), ship-to-shore container cranes are rather comparable to industrial plants than to machines. This becomes even more evident if you consider that the crane wiring schemes alone comprise some 250 pages. While steel construction and assembly are performed in Ireland, the control equipment is manufactured in Germany, in the town of Biberach an der Riss. Liebherr has centralized many activities relating to electronic control at Liebherr-Components Biberach GmbH.
Fig. 3: Sequence of views during disturbance localization
The visualization software developed by Liebherr-Components Biberach GmbH with VisiWin is not installed at the crane operator’s workplace; it is used, for example, when disturbances occur during operation. Under optimal conditions, a Liebherr container crane requires only 40 seconds to transport a container from a ship to a truck. Idle times caused by disturbances in this highly dynamic work environment must be reduced to a minimum, especially since the crane may be in the way of other machines and hinder transportation. This is why maintenance staff need immediate and comprehensive information on the location and the cause of the disturbance. All relevant data are recorded by a PC in the crane control room. These recorded data include not only the time, the speed and the weight of each transported container but also environmental conditions such as wind speed and directions.
Fig. 4: Detailed view of the location of disturbance
Another effective analysis tool is the interactive graphical representation of safety chains, which visualizes the step sequences and the current statuses of active machine processes. The tool allows to analyze and track processes down to the component level. With the 3D model and the status messages, the maintenance staff are provided with the necessary information to determine where exactly one of the many parallel processes was interrupted and can thus identify malfunctioning components. In an urgent case, a “virtual jumper” can then be used: It means that inputs and outputs in the PLC are set to bridge defective sequences on short notice so that the crane can be operated in emergency mode.
Fig. 5: Pushed emergency stop button on the undercarriage
Preventive maintenance is ensured by various statistical functions for the recording and visualization of counter readings, load and engine data or crane movements. The operating data recorded by VisiWin over long periods of time help to detect component overload or wear.
Before they started to use VisiWin, Liebherr used an in-house Windows-based visualization software. Considerable effort was required to maintain the software and, for example, to adapt it to new Windows environments. This was the reason why they decided to outsource the task of software updating for new operating systems and to buy a visualization solution. VisiWin convinced by its WPF programming interface and a wide range of options for 3D graphical representation, which allowed to implement a high degree of visual clarity. In addition, VisiWin made a modularized solution possible that allows to easily adapt the visualization applications to different crane types. INOSOFT has a 20 years experience of software development in the Windows environment and guarantees full compatibility between its own products and with all new Windows versions.
Fig. 6: The huge container cranes are rather comparable to industrial plants than to machines
Another argument in favor of VisiWin was its extensibility for user-developed functions. The VisiWin development environment fully supports the Visual Basic and C# programming languages. Its integration with the professional development tools Visual Studio and Blend by Microsoft allows users to develop custom controls and to add new function blocks as well as third-party components without any problems. On this basis, Liebherr compiled a tool that allows to easily adapt the visualization application to each crane type. Using the development tools that came with the software and their in-house developed extensions, Liebherr created a development environment that provides all functions needed for crane diagnosis and allows to build visualizations for specific crane types. The editor mode created by Liebherr is an example of the integration of custom features – it allows to modify the visualization directly in the installed application. Using a special comment function, maintenance staff can pin “electronic memos” in the Post-It design containing, for example, a comment, a to-do list or a reminder anywhere on the user interface. In summary, Liebherr’s visualization system of choice had to fulfill the following requirements: first, to provide the necessary functional range for the specific requirements of crane controllers; second, to be extensible and flexible enough to implement and integrate Liebherr’s own ideas and functions; and third, to eliminate the need for in-house expenditures on adapting the software to new operating systems. All of these requirements were met by VisiWin.
Liebherr-Components Biberach GmbH was founded in 2012 and belongs to the Components division of the Liebherr group. The company evolved from the splitting up of Liebherr-Werk Biberach GmbH. Until the end of 2011, it developed and manufactured construction cranes as well as large diameter bearings, gearboxes, electrical machines, and control technology systems. Liebherr-Components Biberach GmbH is a manufacturer of high-quality, high-performance drive components such as large diameter bearings, gearboxes, and rope winches as well as electric machines and switchgears. These components and systems are not only used in machines made by Liebherr, they are also in demand from customers outside of the group. They are used in earthmoving machines, in wind turbines, in open-cast mining, in maritime applications, in vehicle and transportation systems as well as in machine tools.