Embedded System in Automobiles

1. Embedded System in Automobiles Visit www.seminarlinks.blogspot.com to download

2. embedded system • A combination of hardware and software which together form a component of a larger machine. • An example of an embedded system is a microprocessor that controls an automobile engine. • An embedded system is designed to run on its own without human intervention, and may be required to respond to events in real time.

3. Block Diagram of A Typical Embedded System

4. Characteristics of embedded systems • Sophisticated functionality Often have to run sophisticated algorithms or multiple algorithms. Often provide sophisticated user interfaces. • Real-time operation • Must finish operations by deadlines. • Hard real time: missing deadline causes failure. • Soft real time: missing deadline results in degraded performance. • Many systems are multi-rate: must handle operations at widely varying rates. • Low manufacturing cost. • Low power. • Designed to tight deadlines by small teams.

5. Applications in automotive system • Air Bags • Traction Control • The Black Box • Automatic Parking • Anti-lock Brake • Adaptive Cruise • Heads-up display Control • Night Vision • Drive by wire • Satellite Radio E.g.: XM • Back-up collision sensor • Telematics E.g.: OnStar • Rain-sensing Wipers • Navigation Systems • Emission Control • Tire Pressure Monitor • Climate Control

7. CAN (Controller Area Network) • CAN is a hardware and software communication protocol for in-vehicle networks in cars. • The applications of CAN in automobiles include engine control communications, body control, and on-board diagnostics. • A CAN bus enables microcontrollers in a car to talk to each other without the need for a network host. • A typical automobile today has dozens of microcontrollers that communicate with each other via various CAN buses. Key Features Maximum Data Rates: 1Mbps at 40m, 125Kbps at 500m, 50kbps at 1000m Circuit Type: Differential Physical Layer: Twisted Wire Pair, 9 pin D-Sub Transmission Format: Asynchronous Drive Voltage: High: 2.75v ~ 4.5v; Low: 0.5v ~ 2.25v; Differential: 1.5v ~ 3.0v Network Topology: Point to Point Standards: ISO 11898/11519

8. CAN Bus Interface Engine Control Unit ECU CAN Buses Transmission Control Node Airbags Control Nodes ABS Node Cruise Control Node Window Mirror Control

9. Airbag System Visit www.seminarlinks.blogspot.com to download

10. EDR-Electronic data recorders • Electronic data recorders- similar to the ‘Black Box’ flight recorders used on airplanes • It records a few seconds of a vehicle’s operation immediately before the crash. • EDRs usually are connected to a vehicle’s air bag control system and continuously record and rerecord data from connected sensors. • In an accident in which air bags are deployed , EDR records are captured for analysis.

11. EDR Block Diagram

12. ANTI-LOCK BRAKE SYSTEM (ABS) • The antilock braking system is designed to prevent wheels locking or skidding, no matter how hard brakes are applied, or how slippery the road surface. • The primary components of the ABS braking system are: • Electronic control unit (ECU) • Hydraulic control unit or modulator • Power booster & master cylinder assembly • Wheel sensor unit

13. BASIC ANTI-LOCK BRAKE SYSTEM sensor sensor Brake Brake ABS control module  Hydraulic Pump Brake Brake sensor sensor

14. Principle of functioning • Wheel-speed sensors detect whether a wheel is showing a tendency to lock-up. • In case of a lock-up tendency, the electronic control unit reduces the braking pressure individually at the wheel concerned. • High-speed correction of the braking pressure up to shortly before the lock-up threshold. • The brake-fluid return together with the closed-loop brake circuits makes this a safe, reliable, and cost-effective system.

15. The vehicle remains steerable even during panic braking The vehicle is remains no longer steerable when the driver hits the brake

16. Traction Control • Traction Control works by regulating the distribution of torque to each wheel of the vehicle. • This stops the tires from spinning, and ensures that the car moves forward. • It also ensures that brake pressure is electronically controlled at each wheel to suppress wheel spin and maintain optimum traction, so drive force is optimally distributed to all four wheels.

17. Vehicle Stability Control (VSC) • System that ensures control in concerning situations the way ABS does under braking and TRC does under acceleration . • The VSC system utilizes electronics sensors in conjunction with the ABS and TRC hardware to help control any potential understeer or oversteer situations. • Understeer is when the vehicle loses front-wheel traction and wants to push forward nose first • OverSteer is when the rear wheels lose traction and tail begins to slide

19. cruise control system • The cruise control system controls the speed of the car by adjusting the throttle position, so it needs sensors to tell it the speed and throttle position. • It also needs to monitor the controls so it can tell what the desired speed is and when to disengage.

20. Adaptive Cruise Control

21. Intelligent Cruise Control • Cooperative Adaptive Cruise Control with Collision Warning (CACC + CW) • CACC: Cruise at given speed when the road is clear (cruise control) otherwise follow the car in front, using radar (adaptive) and/or communications (cooperative). • CW: Warn the driver when an object is being approached too fast, or is too close. Principle of Operation of Adaptive Cruise Control

23. CACC system is effective when the adaptive cruise control fails to perform correctly due to the radar's line-of-sight scanning. • When the car approaches a sharp curve, the DSRC system warns the adaptive cruise control system of any slow moving vehicles just around the turn. • Dedicated Short Range Communications (DSRC) is a data-only automotive communication protocol.

25. Approaching Emergency Vehicle Warning • Vehicle to vehicle DSRC would enable information about an approaching emergency vehicle to be relayed from vehicle to vehicle forward through traffic. • This would help to clear the way for the emergency vehicle and reduce the risk to other vehicles. Information about approaching emergency vehicle sent ahead through vehicle using DSRC

26. Drive by wire • This technology replaces the traditional mechanical control systems with electronic control systems using electromechanical actuators and human-machine interfaces. • It means Drive by wire replaces mechanical connections – push rods, rack & pinion, steering columns, overhead cams, cables – by mechatronic connections – sensors, actuators, embedded microprocessors, control software

27. Drive by wire involves 3 main systems: • Steer by Wire • Throttle by Wire • Brake by Wire

28. Visit www.seminarlinks.blogspot.com to download

31. Conclusion • In the recent years, more and more equipment in automotive are changing from mechanical systems to electronic systems. • Embedded system is a core of vehicle electronic systems because of its flexibility and versatility. • The electronics revolution has influenced almost every aspect of automotive design including the powertrain, fuel combustion, crash protection and the creation of a comfortable cabin and nearly wireless environment. • It is necessary to pay more attention to the fields of environments, safety and security, which are the most significant and challenge field of automotive embedded system design.

32. References • www.wikipedia.org • http://www.cvel.clemson.edu/ • http://auto.howstuffworks.com/ • http://www.toyota.com.au/ • http://www.cdxetextbook.com/