Industrial and embedded marine computers are increasingly being adopted for a wide diversity of maritime applications including Voyage Data Recorders (VDRs). These are the black boxes for ships which record onboard instrument and navigation data. In the event of an incident or accident the VDR data can be analysed, much like a black box recorder of an aircraft after an accident.
The VDR will communicate the collected and processed data, for subsequent permanent storage in a Crash Survivable Module (CSM). The CSM is a tamperproof unit designed to withstand the extreme shock, impact, pressure and heat, which could be associated with a maritime incident. The CSM may be retrieved from the vessel and the stored data replayed by the authorities for investigative purposes.
The International Maritime Organization (IMO) regularly reviews regulations and updates mandatory VDR requirements for cargo vessels greater than specific tonnages travelling in international waters. Presently all vessels exceeding 3,000 tonnes require VDRs to be fitted.
In the maritime world the VDR is typically based on an embedded industrial marine computer which acts as the central data acquisition point for the various parameters being recorded. These can vary between manufacturers and complexity and can include any number of the following:
- GPS – Date, Time & Position
- BRIDGE AUDIO – Internal & External
- VHF COMMS – Communication Channels
- GYRO – Heading
- RADAR – Post Display Image (VDR Only)
- LOG – Speed
- ANEMOMETER – Wind Speed & Direction
- ECHO SOUNDER – Depth
- HULL OPENINGS – Hull Doors
- RUDDER – Order and Response
- AUTOPILOT – Settings & Status
- ENGINE/PROPELLER – Order & Response
- THRUSTERS – Status, Direction, Thrust
Embedded Industrial computers for VDR applications will therefore typically require a high density of I/O ports. These can be conventional RS232 or increasingly USB or Ethernet based where data is digitised and collected via an IP network of sensors. Applications are generally low in processing power, typically acquiring data at relatively slow intervals.
The operating environments can be quite challenging and requiring engineered protection in terms of:
- Shock and vibration
- Wide operating temperature range
- Saline marine environment (corrosion risk)
- Power supply stability
EN60945 certification is usually mandatory which will address the compliance testing of the total VDR equipment (including the embedded computer). Marine computers used in VDR applications will therefore require engineered design and some degree of compliance testing to ensure they will allow the overall VDR to meet this certification standard.