Control Overview

A modular approach...

Ship Dynamics stabilisation comprises a number of functional modules that can be mixed and matched to meet functional requirements.  A modular approach allows the integration of both new and existing equipment into a single system and provided flexibility in system configuration.  Every device connected to a Ship Dynamics system is managed in a consistent manner, irrespective of it location or degree of influence.  No longer do you have to choose what is stabilisation and what is not.

In developing each module Ship Dynamics has given due consideration to the needs of commercial operation.  Our control hardware is based on commercially available "off the shelf" components wherever possible and we choose to operate critical tasks on proven industrial automation platforms rather than bespoke hardware or PCs.  Furthermore marine approvals can be provided for critical systems without change to design.

The available modules are illustrated in the following diagram.

Industrial Ethernet

Ship Dynamics control modules communicate with each other over an industrial Ethernet.  The flexibility of Ethernet network topology allows a network to be configured to provide the level of fault tolerance required of the application.  All Ship Dynamics control modules can operate effectively on a range of network topologies. Simplest option is a star network configuration with all modules radiating out from a single switch.  At the other extreme is a fully managed redundant ring network, where any single point of failure can be managed through an alternate pathway.  A dedicated Ethernet network is installed for the stabilisation system rather than utilizing an existing network, due to the influence that network traffic could have on the critical timing of stabilisation control.

A further benefit of Ethernet is it’s open protocol that allows certain data to be shared with a Ship monitoring system.  A Ship Dynamic system can integrate with other ship systems through ethernet or other industry standard protocols. We can even support your system by accessing recorded data and via a remote modem connected to the network.

Ship Dynamics' approach to control

Ship Dynamics' approach to control is to separate the means of generating a command from the means to actuate a stabilisation device.  The benefit of this approach is that common hardware modules can be applied to a variety of control tasks and that any number of devices can be added to the system.  Whether it is a steering system or full flight control of a hydrofoil, the approach remains consistent.

The control functions and responsibility are illustrated by the following diagram.

Command generation

The Ship Dynamics controller is the heart of any stabilisation system that requires measurement or a system generated command.  Inputs and outputs are handled by an internal data manager.  The data manager can be used to display measured motion or can pass motion data on to the control function block.

The control function block contains the algorithm or computational strategy for control.  By adopting a ‘container’ approach for the control algorithm, alternate control strategies can be substituted to satisfy different application needs.  Such a feature also allows Ship Dynamics to work with developers to implement new and alternate control strategies without change to the underlying control platform.

A device manager advises the controller what is connected to the system at any instant in time and the characteristics of any device connected. Instruction are ultimately output from the device manager to the to each device interface in order to achieve the necessary actuation.  The device manager also manages any voluntary commands input directly by the operator.

Stabilising device actuation

Each stabilisation device is fitted with its own device interface module.  The device interface is responsible for ensuring that local functionality is managed and the issued command is executed safely.  A hard wired back up with provision for local activation of the device is provided for safety in the event of a loss of communication with the Ship Dynamics controller.

Further control functionality can be added to a stabiliser location with the addition of a graphical interface.  Such interfaces can in fact be connected anywhere in the system to display any system parameter.  The degree of local control required is entirely flexible.