Electronic Control (2)

Electronic Control (2)

 

Normally the control system consists of sensor parts which supply the information of moving parts of a vehicle or engine, controller part which processes the signals from sensors and make a proper decision based on the control logic inside of the control program and the actuator part which really does proper actions and generates a necessary movement of a vehicle. Sensors and actuators will be explained later at a separate chapter here in this chapter let’s have a little bit more detail look on the controller itself.

 

The controller looks somewhat different from PC (Personal Computer) but the structure and functions are very similar as PC. There is a keyboard or scanner as an input device of PC, but in case of control unit the sensors are playing the role of input devices. PC has the monitor or printer as an output device, in the CU actuator does the function of output devices. Inside CU the structure is simpler that those of PC because the processing devices to process graphic or sound is not necessary. The general configuration of an ECU (Engine Control Unit) is shown below.

 

The size of an ECU is much smaller that PC, normally the size of PCB (Printed Circuit Board) inside ECU is smaller than 150 cm2, and the size is getting smaller and smaller because of integration technology of semi-conductor industry is getting more and more powerful. The function of micro-controller of ECU and PC is not so different, but the type of work those devices are doing is quite different. PC controller is doing word-processing and graphic touch-up and make music file which the user is interesting, but ECU is doing the simple and same work of calculation such as, engine speed calculation, air mass calculation or vehicle speed calculation ever and ever. To ECU fancy work like those of PC is not given, the duty of ECU is doing the simple and routine work ever and ever without any error.

 

The scenario of this routine work is recorded in the ROM (Read Only Memory) of ECU. The scenario was created by ECU supplier company and the date inside was made by calibration engineer of the vehicle manufacturer of engineering company who is doing the work for the OEM. In the scenario, all the cases which vehicle can confront from the birth to the scrap is recorded and the ECU is simply doing the duty thousands of millions of times.

 

Now, is it really good to go to this “electronic controlling way” ? Is it really better to replace interruption of human for the control of a vehicle ? Before the control unit comes to the world, a traditional mechanic can repair all kind of mechanical failure of engine and vehicle, but now, after ECU is installed to control everything, it is really not possible for a traditional mechanic to repair a control system. Without diagnosis devices nobody can touch the system.

 

One more disadvantage of ECU is the possibility of electro-magnetic interference. Because the controllers are controlling all the major parts of vehicle like engine and transmission, one small malfunction can cause very critical damage of human body or property. Today the numbers of devices which emit electro-magnetic wave inside vehicle are sharply increasing and also the numbers of devices the drivers are bringing and holding are also increasing. In this environmental condition this tendency of electro-magnetic interference failure is getting higher and higher.

Even if the ECU has this kind of disadvantage, the major advantage which this system can bring is overriding this “small” amount of disadvantage, therefore the numbers of control unit inside a vehicle will increase further.

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