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A new design for propulsion control

The new Wärtsilä Propulsion Control System is a comprehensive system of levers and touch-screen interfaces, designed to suit all the possible propulsion configurations of a modern ship. The first pilot installations will be delivered in Q3 of this year. The design has won the highest prize of product design in the internationally recognised design competition Red Dot Award.

Text: ROBERT DE LANGE, GENERAL MANAGER PROPULSION CONTROLS R&D Photo: -

In 2010, R&D activities were initiated within Wärtsilä’s Product Centre Automation with the aim of better aligning the design of the propulsion control systems to the requirements of the market. The technology in use at the time was simply not able to fulfil the latest demands with respect to size (footprint), ease of use, installation, and commissioning efforts anymore, as ship navigating bridges are now equipped with an increasing number of electronic systems.Other requirements included the optimisation of Wärtsilä’s engineering, assembly, and test efforts per delivery project, as well as the establishment of a clear brand identity for the solution.  

The new system should be flexible enough  to be applicable for all types of ships, from simple cargo carriers to more complicated offshore supply vessels, and should support the Wärtsilä Communication and Control Centre (Wärtsilä 3C) integrated bridge concept by controlling Wärtsilä’s own and OEM propulsors.

Industrial Designers

Wärtsilä’s industrial design team made a major contribution to the project during the early stages of the development phase. Their systematic approach included collecting end user values by interviewing operators, and ranking them according to the demands of the market segments (vessel types). The interviews revealed, among other things, the need for procedures guided by the system, an intuitive command transfer and station overview, a mode status indication of the lever, the use of mechanical switches only for critical functions, and the use of motorized levers.

Interactive prototypes and mock-ups were used during the development process to validate the key features of the concept, their applications and the ergonomics of the devices. This approach provided support to the conceptual discussions, even before any real hardware or software design activities were carried out.

During the detailed design phase, when technology and vendors are to be selected and the first prototypes made, the involvement of industrial design specialists is important. Optimisation has been achieved by using rapid prototyping techniques, by developing guidelines for the materials to be used, by ensuring that the concept itself is not compromised, and by properly evaluating manufacturing costs.

Finally, industrial designers are involved during the  software development phases of the Graphical User Interface (GUI) by giving input to the user interaction design specification.

Product Concept

The final product concept consists of a lever, a 4.3 ”side display and an optional 10” main display. Manual control of thrust is by the lever, the side display takes care of the individual propulsor control functions where as the main display is the single user interface for common functions related to all propulsors and propulsion modes which improve the ease of use.

This modularity supports yards to design their bridge consoles much more flexible.

All displays are equipped with touch technology, and all bridge devices will be connected to the system using field-bus technology (CAN OPEN). The basic version of the propulsion control system comprises of a lever and a corresponding side display. Overhead indicators to show the controlled parameters like steering angle, pitch, RPM etc. are present to fulfill class rules and regulations, as well as the European rules relating to indications onboard sea going ships.

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Fig. 1 – The new user interface of Wärtsilä's Propulsion Control System.
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Fig. 2 – 2CPP/FPP, 4TT, 2STT retractable with side displays and main display.

Product Configuration

The newly developed product consists of 2 independent systems (normal and back-up) each with its own field-bus network. The levers, displays, and indicators are connected to either one or both networks depending on their functionality within each system. Electrically, both networks are separated. Another independent field-bus is present to indicate the steering angle. Emergency stop connections remain hard wired directly from the bridge to the machinery equipment.

The individual propulsion systems are connected to the bridge networks using two controllers (gateways), which are located at a Bridge Control Unit (BCU) control cabinet. Also this connection is via CAN OPEN field-bus. A single BCU can connect up to four propulsion control systems. The separation between port and starboard is simply achieved by using two BCU’s for a twin screw vessel.

The big advantage of this configuration is that it allows for the exchange of data betweenall connected propulsion systems at bridge level, while still meeting the requirements of redundancy and independency, as stipulated by the class rules for propulsion with an optimum amount of physical connections (wires).

Important interfaces with external systems can be supported by field-bus or Ethernet connections that do not interfere with the internal field-bus. The system allows for future extensions of functionality, and integration with other systems without a large change in hardware scope. Monitoring, as well as the trending and tuning of multiple thrusters, becomes possible at the bridge location using a single service connection on site, or even remotely using the features of Wärtsilä’s plant net.

Levers

Six different levers have been developed using a modular approach. Available are a single and double lever for fixed pitch / controllable pitch (FPP/CPP) main propellers and tunnel thrusters (TT), as well as a lever for steerable thrusters (STT) and water-jets (WJ). Each lever is equipped with stepper motor(s) and hall sensor technology for position feedback.

Normally, so-called E-shaft levers are only used to follow the lever or system in control, thereby acting as a slave lever at a bridge station not in command. However, by controlling the stepper motor accurately, it becomes possible to have what is known as electronic detents, i.e. at certain positions of the lever, the torque of the stepper motor is controlled, thus leading to a notch (a position in the stroke of the lever with higher resistance) that gives the operator haptic feedback. This technology can also be used to inform the operator on (temporarily) existing operational limits of the propulsion plant, propulsor or selected sailing mode.

The main propulsion levers are equipped with an independent back-up controller and a selection pushbutton with a cover to prevent unwanted use. The advantage for the operator is that when selecting the back-up system for the remote control of the propulsor, the user input device remains the same. In the past, pushbuttons or toggles with a complete different dynamic behaviour, as well as system response, had to be used. 

Each lever is equipped with an emergency stop pushbutton, again with a precautionary cover. The emergency stop circuitry is independent of the CAN OPEN field-bus connections, and can be used for either emergency stop of the driving diesel engine / electro motor, or emergency disengagement of the propeller clutch.

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Fig. 3 – System configuration.
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Fig. 4 – CPP lever with integrated status LED indicator.

Each lever is equipped with a led bar. The steerable thrusters and water-jet levers use a circular led bar to indicate the steering ability of the propulsor, whereas the main and side thrusters have a straight led bar.

The colour of the led bar is used to give the operator instant and valuable information regarding the status of the propulsor. Off means the propulsor is stopped normally, dark blue means the propulsor is in manual mode, while light blue means the propulsor is controlled by an external system, such as DP (Dynamic Positioning system) or JS (Joystick). Orange means a mode transition is in progress, yellow means back-up mode is active, and red means the propulsor has been abnormally stopped.

The dimensions of each lever are the same, 144 x 144 (HxW in [mm])

Displays & GUI’s

The displays are in two sizes; a 4.3” side display and a 10” main display. Both displays use capacitive touch technology and are designed with a special emphasis on brightness, viewing angle, and backlight life time. The mandatory EMC and environmental requirements for propulsion 
equipment installed on the navigation bridges of sea going vessels have, of course, been applied.

The size of the side display is 144 x 72 (HxW in [mm]) and the main display size is 308 x 211 (HxW in [mm]). For the main display, a hinged version is also available as an option in case there is a need for adapting the viewing angle towards the operator.

The software platform contains a Linux based operating system in combination with Codesys for the domain logic while the touch-screen interface is based upon a Q-T cross-platform application, and another part takes care of the data nodes. Besides this, a distribution framework is present to take care of the communication needed for service tools. The displays, as well as the BCU gateway controllers, utilize the same hard 
and software platform.

GUI side display

The concept identified that each lever should have a corresponding side display. Side displays are developed as stand-alone units and can be put next to the lever in a portrait or landscape position. Night and day colour schedules are present.

The GUI is built up with areas wherein information or functionality is always present (fixed) and / or areas where the user can slide or select the requested functionality.  Colours are used in a systematic way and in line with the levers, i.e. grey for normally stopped or not available, blue for in control, green for on or running or ok, yellow for warning, orange for in progress or transition periods, and red for abnormally stopped or a failure situation.

In general, when buttons are pressed (e.g. to start) an automatic sequence starts whereby another button pops up at a slightly different location on the touch screen to confirm or abort the requested operation and thus, two touches are always needed to set the requested action so as to avoid inadvertent use.

The top area has fixed information, such as propulsion tag and power available indications. Also at the top area, buttons are present for control transfer and mode overrides.

In the middle area, pages for system information, mode and propulsor control, and gauges for steering, pitch, RPM and load, are present. At the bottom of this area, active page indication dots are present to guide the user through the pages.  Altogether, 12 pages are defined in two rows of six. Horizontal and vertical scrolling is possible. 

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Fig. 5 – GUI main display (day mode).
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Fig. 6 – GUI side display landscape (day mode).

At each gauge, the value of the monitored or controlled variable is indicated by an analogue pointer, as well as by a digital value. If a controlled value is monitored, the black pointer indicates the actual value and another orange pointer indicates the requested value or set-point. When the set-point meets actual, only the black pointer is visible.

At the bottom area, buttons for the propulsor start/stop in automatic sequence (e.g. all related systems, such as hydraulics, lubrication, prime mover(s), and propeller clutches) are envisaged, as well as (fixed) information on the status of the steering and / or thrust systems.  Additionally,  at the bottom a dimmer slide, as well as the test button, is present. The buttons and background colour have a night and a day mode appearance, which is selected automatically with the dimmer.

GUI main display

The concept identified that a main display has real benefit for vessels with an increasing number of propulsion levers at each control position.  With the main display, the common interactions that the operator has to perform on all propulsors can be controlled from a single user interface. Obvious examples are, for instance, dimming, control transfer, mode selections and event warnings, which are  all concentrated on this main display.

The use of the main display enables the operator to better focus on his navigational duties. Information when needed will pop-up, and when interaction is required it is easily reachable and accessible.

The main display is divided into two major parts. The left part shows a mimic of the vessel (forward or aft looking) where each propulsor is clearly identified through the use of an interactive propulsor info button with a tag name. For thrusters with steering capabilities, a circular object is used for this tag, just as with the lever.

In the middle area of the vessel’s mimic, buttons are present for synchronous control transfer from and to control positions, such as the aft bridge, port or stbd wings, and ECR of all propulsors.

The right part has a large pop-up area for settings, events, and a propulsor side display mimic. This last feature means that when the operator presses the propulsor info button on the main display, the corresponding side display mimic pops up with all the features present on that side display for that propulsor included, thus creating a full redundancy for those functions.

On top of the right part, mode selections and overrides can be activated.  With a mode override, the operator can decide to take an individual thruster out of the selected mode, like DP or JS, and use that thruster in manual mode.  The corresponding colour will turn from light blue to dark blue.

At the bottom of the main display, an area with fixed buttons is present for the selection of the night and day colour scheme, the changing of settings, a dimming slider and an event and test button.

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Fig. 7 – GUI side display portrait with orange pointer (day and night mode).
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Fig. 8 – STT lever with side display portrait (day mode).

CONCLUSION

With the new Wärtsilä Propulsion Control System, the user is intuitively in control in all situations and under all conditions. The system’s modularity makes installing, commissioning, configuration and maintenance simple and efficient, thus saving valuable time. By removing the visual challenge of finding critical information in large panels of buttons and gauges, and by giving the user relevant information when needed, the system improves safety, both at sea and in port. With Wärtsilä’s tradition of innovation, even complex systems like this can be taken to a new level by means of effective design. 

Wärtsilä Propulsion Control Systems
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Fig. 9 – CPP lever (detail of the production quality).

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