An electronic control unit (ECU) is an embedded system in vehicle electronics that is responsible for controlling a specific function.
A vehicle could have + 100 ECUs, controlling functions that range from the essential (such as engine and, steering) to comfort (such as heated seats, and air-conditioning).
An ECU also control the security and access (such as door locks, and keyless entry), and passive (such as airbags), and active safety features (such as automatic emergency braking).
An ECU receives inputs from different parts of the vehicle, depending on its function. In order to control a function each ECU typically contains a chip that runs its own software or firmware and requires power and data connections to function. For example, if a sensor detect that the vehicle is approaching an object too fast, it will send signals to the automatic emergency braking ECU. The ECU would then communicate to actuators to perform an action based on the inputs. For instance, the automatic emergency braking ECU would engage the brakes to prevent a collision.
As vehicle manufacturers continue to add features and functions, space is becoming an issue. Each new feature requires a new ECU, new cable solutions, and OEMs are running out of places to put them. This incremental approach also becomes inefficient.
In years to come, it would be logical to find less ECU’s in vehicles, and OEM’s to adapt their vehicle architecture to software-defined vehicles.