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Automotive electronics first began with the need for better controls for the engine. In fact, the first electronic parts in automobiles were used to control various engine functions and were referred to as ECUs (Engine Control Units). However, as electronic controls began to be used for other automotive applications, the acronym ECU took on the more general meaning “electronic control unit”. Today, specific ECUs are generally referred to as modules [e.g. the engine control module (ECM) or the Transmission Control Module (TCM)]. A modern car may have up to 100 electronic control units and a commercial vehicle up to 40.
Automotive electronics or automotive embedded systems are distributed systems and according to different domains in the automotive field they can be classified into:
- Engine Electronics
- Transmission Electronics
- Chassis Electronics
- Active Safety
- Driver assistance
- Passenger Comfort
- Infotainment systems
One of the most demanding electronic part of an automobile is the engine control unit. Engine controls demand one of the highest real time deadlines, as the engine itself is very fast and complex part of the automobile. Of all the electronics in any car the computing power of the engine control unit is the highest, typically a 32-bit processor.
It controls different things like:
In a diesel engine:
- Fuel injection rate
- Emission control, Nox control
- Regeneration of oxidation catalytic converter
- Turbocharger control
- Cooling system control
- Throttle control
In a gasoline engine:
- Lambda control
- OBD OnBoard diagnosis
- Cooling system control
- Ignition system control
- Lubrication system control (only few has electronic control)
- Fuel injection rate control
- Throttle control
Many more engine parameters are actively monitored and controlled in real-time.
There are lots of sensors about 20-50, which measure pressure, temperature, flow, engine speed, oxygen level and NOx level and more parameters at different points in an engine. All these sensed signals are sent to the ECU, the ECU has a logic and does the control. The ECU output is connected to different actuators like throttle valve actuation, actuation of an EGR valve, rack actuator in VGT Turbocharger, pulse width actuation in a fuel injector, dosing injector actuation and lots more about 20-30 actuators.
This controls the transmission system; mainly it controls the shifting process of the gears. For a better shift comfort, lower torque interrupt while shafting -these electronics are used in a manual transmission. Many semi automatic transmissions which have a fully automatic clutch or a semi-auto clutch (only declutching) use electronics for its operation and control. Also fully automatic transmissions use controls for their operation.
The engine control unit and the transmission control interchange messages, sensed signals and control signals for their operation.
The chassis systems has lot of sub-systems which monitors different parameters and are controlled actively.
- ABS - Anti-lock braking system
- TCS – Traction control system
- EBD – Electronic brake distribution
- ESP – Electronic Stability Program
These systems are always ready to act when there is a collision or to prevent it when it senses the situation.
- Air Bags
- Hill Descent Control
- Emergency Brake Assist System
- Lane assist system
- Speed assist system
- Blind spot detection
- Park assist System
- Adaptive Cruise Control System
- Automatic Climate control
- Electronic seat adjustment with memory
- Automatic wipers
- Automatic Headlamps – adjusts beam automatically
- Navigation system
- Music system
- Information access
All of the above systems forms an infotainment system.
Developmental methods for these systems vary according to each manufacturer.
Different tools are used for both hardware and software development.
Functional Safety Requirements
In order to minimize the risk of dangerous failures, safety related electronic systems have to be developed following the applicable product liability requirements. A disregard or inadequate application of these standards can lead to not only personal injuries, but also to severe legal and economic consequences such as product cancellations.
The IEC 61508 standard, generally applicable to electrical/electronic/programmable safety-related products, is only partially adequate for automotive-development requirements. Consequently, for the automotive industry, this standard is replaced by the existing ISO 26262, currently released as a Final Draft International Standard (FDIS). ISO/DIS 26262 describes the entire product life-cycle of safety related electrical/electronic systems for road vehicles. It has been published as International Standard in its final version in November 2011. The implementation of this new standard will result in modifications and various innovations in the automobile electronics development process, as it covers the complete product life-cycle from the concept phase until its decommissioning.
When developing electric vehicles, it is very essential to observe all electrical, chemical, and mechanical safety aspects. The development of safe, high voltage batteries is regarded as a major challenge. There is still no appendage that addresses safety-related aspects of electric propulsion and storage systems. As a result, it is quite a challenge to navigate through the inconsistencies and gaps in the technical standards and legal requirements.