Matrix Board Communication

This DDS-Demonstrator is inspired by the communication of the well know “Matrix Boards” above the (Dutch) Highways.
Each MatrixBoard shows the maximal allowed speed; during traffic-jams. It needs the input from the next two boards; whose sensors measure the speed at that location.

The real MatrixBoards have sensors (to measure the number of cars, there speed, etc), an actuators (showing the speed), and some simple algorithms (like: “the step is speed between 2 boards is small” and “when the speed changes, the light should blink for some time”). The communication between board is are hard-wired; by using land-lans.

Demonstrator: MatrixBoard MBC_001

status: import tags: MBC

The MatrixBoard DDS-Demonstrator shows some dynamic aspects of DDS in a similar setup. It uses DDS for all communication. It does not implement the real MatrixBoards: it has no sensors, no actuators, nor the exact algorithms. The former two are (very simple) simulated; and the algorithms are replaces by simple rules (roughly doing the same). When running a set of MatrixBoards, each MatrixBoard is started with a location (thinks about a “hectometer sign”). It should automatically “find” the next two ‘upstream’ MatrixBoards and subscribe to those; only. Whenever the set of MatrixBoards changes, a MatrixBoard should automatically discover the new setup and act accordingly (cancel and add subscriptions)

Example

Given a setup like below, where the MatrixBoard at loc=3 does not yet exist; and loc=21 does.

• MatrixBoard at loc=1 should subscribe to loc=2 and loc=5.
• MatrixBoard at loc=8 should subscribe to loc=13 and loc=21.

Now suppose, MatrixBoard loc=3 is added and/or loc=21 is abruptly killed. Then:

• MatrixBoard at loc=1 will use loc=2 and loc=3 (and not listen to loc=5 anymore).
• MatrixBoard at loc=8 will add loc=34 to is subscription-list.