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Electronics & Control

The hardware and software tasks were focused on producing a closed loop feedback ventilation system, sensing smoke density and manipulating the fan speeds of the ventilation system to best deal with the smoke based on experimental analysis of smoke behaviour. This setup would be in a prototype form to be installed on the test rig.

Hardware

The hardware is the medium though which the software control system is able to interact with the real world. Firstly data must be gathered using a sensory array. Two types of sensor were used: smoke sensors and temperature sensors. The temperature sensors were included as the secondary role of the control system was to log sensory data during experiments for analysis and the temperature readings could be used to ensure similarities between the experiments and computer simulations were close enough to allow meaningful comparisons to be made.

The other half of the hardware section was producing a scale model of a ventilation system. This was simplified to recreating the airflow at the room/ducting interface. As DC brushless fans were used, which cannot change their airflow direction, two fan were mounted in opposing directions to achieve bidirectional airflow. The fans measured 40mm in diameter and were comparable in throughput and dimensions to commercial ventilation fans when scaled up appropriately.

All of the sensors and fans were connected to a network of microcontrollers - each microcontroller being responsible for one geographical area allowing the location of the sensor readings and fans to be located. The microcontrollers were connected together over an I2C network with one controller acting as the master. This master also communicated with the control PC over an RS232 connection, acting as a gateway between the controller net and the PC.

Software

The software acted as the brain of the control system. Incoming data from the sensors was processed and using a series of control laws which then instructed the fans to act accordingly. Communications with the microcontroller network was over an RS232 connections using a custom network layer protcol dubbed SmokeTalk. SmokeTalk uses concepts from the TCP/IP protocol suite and adopts a packet based format.