Embedded, as the name suggests refers to something attached to another thing. Embedded systems can be defined as a computer systems having a combination of hardware and software which is designed to perform a specific task within a larger system which can be electronic, electrical or mechanical system. In Automobile industry, it was the Volkswagen company that first introduced Embedded systems in its cars in the year 1968. After that the applications of embedded systems in automobiles have been rapidly increasing due to the flexibility and versatility of these systems as they can easily fit into different parts in an auto. This has prompted auto producers advancing their plans and ideas around the utilization of embedded systems. Today, nearly 40% of the cost being paid to a car is towards electronics and software. The embedded systems in automobiles mainly find their applications in security, audio systems, and ignition and contribute in making the car safer, energy-efficient, and network savvy. Normal vehicles that run today consist of 25-35 microcontrollers and this number goes up to 60-70 microcontrollers for luxury vehicles.
There are five major functional domains of Automotive in which Embedded systems are implemented. They are Chassis, Power train, HMI, Telematics and Diagnostics.
Chassis– The chassis domain consists of the four wheels and their relative position and movement; in this domain, the embedded systems found are mainly steering braking and suspension. This domain includes systems like Antilock Braking System, Electronic Stability Program, Automatic Stability Control etc.
Power train– The power train domain is related to the systems that participate in the longitudinal propulsion of the vehicle, including engine, transmission, and all subsidiary components. It is designed to optimize certain parameters like driving facilities, driving comfort, fuel consumption, etc.
HMI– It stands for Human Machine Interface domain includes the equipments allowing information exchange between electronic systems and the driver (displays and switches). It also consists of In-vehicle entertainment embedded systems.
Telematics– This domain is related to components allowing information exchange between the vehicle and the outside world (radio, navigation system, Internet access, payment etc.).
Diagnostics-A system that can access and relate information about the vehicle is obviously very essential and is designed simultaneously with the original design of the vehicle.In particular, specifying a system that is responsible for collecting information and establishing onboard diagnostics (OBD) is advantageous for the vehicle’s owner as well as for a repair technician. The generic term used for this function is “on board diagnostics” or OBD.
As more complex control systems are used in automobiles, there is a requirement of more distributed automotive embedded systems. Automotive embedded systems are distributed throughout modern vehicles using multiple vehicle networks partitioned across a variety of different electronic modules. To serve this purpose, many automotive-embedded networks such as local interconnect networks (LIN), CAN, TTP/C, Flex Ray, MOST, and IDB-1394 were developed.
Controller Area Network or CAN as called commonly, is a serial communication multi-master protocol internationally standardized by ISO. The applications of CAN include engine control communications, body control and diagnostics. It enables micro-controllers to communication to each other.
Flex-Ray is an automotive network communications protocol developed by the Flex Ray Consortium to govern on-board automotive computing. Although expensive than other networks, it is deigned to be faster and more reliable than CAN and TTP.
The LIN bus is an inexpensive serial communications protocol, which effectively supports remote application within a car’s network. It is particularly intended for mechatronic nodes in distributed automotive applications, but is equally suited to industrial applications. It is designed in such a way that it can complement the existing CAN leading to hierarchical networks within cars.
The presence of communication protocols has introduced the concept of multiplexing. The main advantage of multiplexing is a considerable reduction in the wiring cost. It also provides flexibility to designers; data (e.g., vehicle speed) sampled by one microcontroller becomes available to distant functions that eliminates the need of additional sensors or links.
Today, up to 2500 signals (i.e., elementary information such as the speed of the vehicle, temperature, throttle position, manifold pressure etc.) are exchanged through up to 70 electronic control units (ECUs) on five different types of networks.
Some of the current trends of embedded systems in automobiles include air bags, event data recorders, anti-lock brake systems, cruise control, rain-sensing wipers, emission control, traction control, automatic parking, in-vehicle entertainment, back-up collision sensors, navigation systems and tire-pressure monitors.
Airbags– It is a thin nylon fabric bag folded neatly into steering wheel that inflates to the size of a large beach ball on impact. It is an important safety device that provides protection against head-on crash for the passengers, by giving a soft surface to land on. This system functions on commands received from the airbag control unit, which is micro-controller based.
The controller gets power from the battery. If the collision sensor detects an accident, a signal is sent to the airbag control unit and it is processed by the airbag control unit to determine severity of the impact. If airbag deployment is necessary, the airbag control unit sends a signal to initiate airbag inflators.
Adaptive Cruise Control system– One of the important innovations in the embedded system used in automobiles is Adaptive Cruise Control technology. With this technology we can also make driver-less vehicle control a reality. Today, many automobile manufacturers are already engaged in working on these systems. This adaptive cruise control allows cars to run at a constant speed on empty roads as well as to keep safe distances from other vehicles on the busy highway roads. The driver of the car can set the speed of his vehicle and the distance between his car and other vehicles. When the traffic slows down, ACC changes vehicle speed using moderate braking.
Event Data Recorders– They are devices installed in automobiles for the purpose of recording dynamic parameters of vehicles like speed, change in velocity, braking force applied as well as occupant information for a brief period before, during, and after a triggering event like a crash or near-crash event. It is sometimes also referred as “black-box” data, these data or event records can be valuable while analyzing and reconstructing the event.
Embedded Navigation systems– It is another advancement of the embedded system in automobiles. The navigation is performed system using GPS system. This navigational system consists of an embedded circuitry built with a GPS receiver, a gyroscope, a DVD-ROM, main controller and a display system. The GPS receiver receives the current longitude and latitude values that are compared with the stored map. The Gyroscope and other sensors provide the road direction and speed. From all the information gathered at the main controller, the display system displays a navigation or route map of the destination in the display screen.