Knowing where you are and staying there within a certain degree of accuracy is no longer just a luxury but a necessity in offshore installation and maintenance work. The ability to get men and equipment onto wind turbine installation as and when required during installation or during operation for maintenance is imperative for the economics of cost reduction. For wind farms situated at more distant offshore locations we have seen recent developments with walk to work vessels of various designs.
Common feature for all of them are DP systems and a motion compensated gangway. The control of a ship in the horizontal plane, position over the sea bed, is the responsibility of the dynamic positioning system. The motion compensated gangway can mitigate the effects of the sea and weather. The one compliments the other, and both are needed for the safe transfer of personnel and equipment. The eyes and ears of a DP system are the reference sensors.
Early DP systems used a single taut wire fixed at a known reference position on the sea bed and tethered to the vessel with an analogue device able to measure the deviation away from this point the output would then be would then be applied to the control of multiple propellers or thrusters.
Feed the system
A modern DP vessel may be equipped with many ways to determine the position including GPS, Hydro Acoustic, Laser, Microwave, Light taut wire. They feed the system the information of where in the world it is, either a geographical position on the globe – such with GPS or with relation to a certain point – a local referential sensor, such as with radar and/or lasers providing a range and bearing to a reference point.
This is an enormous amount of information to be displayed and accessed by DP Operator. The design of interface between the DP system and human input or control, the DP Operator, is determined ergonomically.
Guidance Marine
Offshore WIND asked Guidance Marine to describe their approach to designing the DP Operator’s working environment. The exponential growth of technology has led to more accessible technology, and that in turn has led to more connected technology. The increased connectivity has brought about the age of ‘Big Data’, where the amount of information that is available is also doubling. For a computer system this is not a problem, as they are also increasing in performance at a roughly similar rate.
For a human however this has led to an increase in the potential for informational overload – there are so many things to look at it is hard to know what should command attention.
This problem is familiar to practitioners of Human Factors – a branch of science devoted to the study of human behaviour, cognition, and ability. Research that is performed into human factors in areas such as learning, memory recall, building system metaphors, consistency, and effects of system feedback can be transferred into product design. Part of the field of Human Factors is Ergonomics. Ergonomics is the Science of making the job fit the person.
User Centred Design focusses the design of a system on the needs, wants and limitations of the end user. It is unusual in a technology driven business to consider the needs of the User above the abilities of the technologies, however it is central to ensuring that the technologies can be exploited efficiently and safely. An important part of the user centred design process is the understanding of the user’s domain, and the stereotypes that are applied there.
An example is the use of a ‘desktop’ on modern computers. In an office environment there are generally desks, and users are used to placing items on the desk. The ‘Desktop’ stereotype was pioneered by Xerox at the PARC research institute, when the future of the office was thought to be paperless.
We must ‘Seek first to understand’
Domain stereotypes for DP operators vary considerably from those of a software developer. As a result there is a greater need to actually interact with the end users and gather an understanding of the domain than would be the case in, for instance, a webpage design. This need can only be fulfilled by interaction in the actual domain, and a careful approach to understanding.
Guidance Marine use a technique called ‘Voice of the Customer’ (VOC) for these situations. The VOC principles that are taught to practitioners include the ability to listen objectively, and avoid talking. The interview technique is considered most successful if the interviewee has spent 90% of the time talking, with only guidance by the interviewer towards the areas that are most valuable.
The data gathered has to then be sifted as a secondary operation, to avoid being distracted during the valuable time in front of the domain expert. For the Guidance Marine Dashboard user interface this has occurred over a period of time, with multiple iterations of a basic scheme derived from initial interviews and existing user interfaces. Depending on the amount of information necessary to be accessed at the same time there can be 3D, 2D bird’s eye displays or alpha numeric displays or a combination of them all. Listening to the end user and understanding their needs is paramount.
With thanks to Guidance Marine