On-board Unit (OBU)

The purpose of the On-Board Unit (OBU) is to monitor and control the operation of the train and to manage the various modes of the train.

  • Manage Operational mode of the train
  • Manage Remote take-over mode of the train
  • Traction control
  • Speed and direction supervision
  • Automatic Train Operation (ATO) (“Driver less” operation)
  • Train positioning
  • Interface to the Driver Machine Interface (DMI) - the train drivers (remote) panel
  • Interface to RBC

Communication with RBC

The OBU will maintain a communication channel with the RBC for position reports, movement authorities etc. The RBC will consider the communication active as long as it receives position reports from the OBU on a regular basis. The OBU will not monitor the communication as such as it may operate without connection to the RBC (e.g. in mode SR or SH).

Position report

The OBU will send a position report to the RBC at regular intervals (~2 seconds). The report will include the position of the train but also various other data and requests relevant for the RBC.

  • Train ID
  • ID of most recently read balise
  • Relative distance (with sign) between the most recently read balise and the balise reading antenna at the train.
  • Actual driving direction (up or down)
  • Actual driving speed
  • Actual Operational mode
  • Actual Remote take-over mode
  • Actual state of the DMI communication channel
  • Actual status of motor power supply
  • Driver request for Operational Mode and driving direction (“Start of mission”).
  • MA request


Triggered by the position report from the OBU, the RBC will send authorizations etc. to the OBU.

  • Train ID
  • Operational Mode authorization
  • Remote take-over command
  • Movement authorization

The RBC will send authorizations triggered by position reports in an asyncronuous way.That is, the RBC may skip replying on a position report or may even send more authorizations between receiving position reports.

Communication with DMI

The OBU will maintain a communication channel with the DMI providing indications to and receiving commands from the driver.

The communication will follow a polling scheme where the OBU regularly sends indication packets to the DMI. Triggered by this packet the DMI will reply with information on the current driver commands.

The OBU will consider the communication channel active as long as the DMI replies to the packets. Status of this channel will be indicated to the RBC via the position report.

The DMI will consider the communication active as long as the OBU is sending packets. Loss of communication is indicated to the driver via the Status Indicator (flashing Blue).

it/wintertrainv4/design/train/obu.txt · Last modified: 2018/11/18 17:33 by jabe