AUTOMOTIVE SAFETY

Automobile safety

• Automobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of automobile accidents. (Road traffic safety more broadly includes roadway design.)

Active and passive safety: 

Active safety:

• it refers to devices and systems that help keep a car under control and prevent an accident. These devices are usually automated to help compensate for human error -- the single biggest cause of car accidents.
  
  example:
• Anti-lock brakes prevent the wheels from locking up when the driver brakes, enabling the driver to steer while braking.
• Traction control systems prevent the wheels from slipping while the car is accelerating.
• Electronic stability control keeps the car under control and on the road.

Passive safety:

• it refers to systems in the car that protect the driver and passengers from injury if an accident does occur.

Example:

• Air bags provide a cushion to protect the driver and passengers during a crash.
• Seat belts hold passengers in place so that they aren't thrown forward or ejected from the car.
• Rollover bars protect the car's occupants from injury if the vehicle rolls over during an accident.

Head restraints prevent the driver and passengers from getting whiplash during a rear-end collision.

Crash avoidance:

 
Crash avoidance systems and devices help the driver — and, increasingly, help the vehicle itself —to avoid a collision. This category includes:

1.  The vehicle's headlamps, reflectors, and other lights and signals
2.  The vehicle's mirrors
3.  The vehicle's brakes, steering, and suspension systems

Driver assistance:

A subset of crash avoidance is driver assistance systems, which help the driver to detect
ordinarily-hidden obstacles and to control the vehicle. Driver assistance systems include:

i) Automatic Braking systems to prevent or reduce the severity of collision.

ii) Infrared night vision systems to increase seeing distance beyond headlamp range

iii)Adaptive high beam which automatically and continuously adapts the headlamp range to      the distance of vehicles ahead or which are oncoming

iv)Adaptive headlamps swivels headlamps around corners 

v) Reverse backup sensors, which alert drivers to difficult-to-see objects in their path when   reversing

vi) Backup camera

vii)Adaptive cruise control which maintains a safe distance from the vehicle in front
viii)Lane departure warning systems to alert the driver of an unintended departure from            the intended lane of travel                                                                                                      

ix) Tire pressure monitoring systems or Deflation Detection Systems

x)Traction control systems which restore traction if driven wheels begin to spin

xi) Electronic Stability Control, which intervenes to avert an impending loss of control 

xii) Anti-lock braking systems

xiii)Electronic brake-force distribution systems

xiv)Emergency brake assist systems

xv) Cornering Brake Control systems

xvi) Pre-crash system

xvii) Automated parking system 

1)Electronic brake-force distribution (EBD):

 

 It is coupled with ABS 

 Components: 

Speed sensors: 
To determine the slip ratio of a wheel, the EBD system needs two pieces of information: the speed at which the wheel is rotating and the speed of the car. If the speed at which the wheel is rotating is slower than the speed at which the car is moving, then the wheel is slipping and a skid can result. A sensor is placed at each wheel to determine wheel speed. 

Brake force modulators: Brake force is applied to the wheels hydraulically, with brake fluid pumped into brake lines in such a way as to pneumatically activate the brake cylinders. The EBD system can modulate the amount of brake fluid going to each wheel through electrically actuated valves.

• It is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's brakes, based on road conditions, speed, loading, etc. Always coupled with anti-lock braking systems, EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control^. Typically, the front end carries the most weight and EBD distributes less braking pressure to the rear brakes so the rear brakes do not lock up and cause a skid.In some systems, EBD distributes more braking pressure at the rear brakes during initial brake application before the effects of weight transfer become apparent.

• During braking first the brake has to be applied at the rear side.After that weight shifting will take place.So we have apply the front brakes to avoid the skidding.These are done by EBD.

Electronic Control Unit (ECU): 

• The ECU is a small computer embedded in the anti lock braking system. It receives input from the speed sensors, calculates the slip ratio of the wheels, and uses the brake force modulators to apply an appropriate amount of force to keep the slip ratio of each wheel within a reasonable range.

• Most EBD systems also include a yaw sensor, which detects the rotation of the vehicle as it turns. This can be compared with the angle of the steering wheel by using a steering wheel angle sensor to detect over-steer (too much rotation relative to the angle of the wheel) or under-steer (not enough rotation relative to the angle of the wheel). EBD can then correct the steering by activating one of the rear brakes. For instance, if the car begins to understeer, the inner rear brake is activated to increase the car's rotation. If the car begins to oversteer, the outer rear brake is activated to decrease the car's rotation.                                                                                               

2) ESP:(Electronic Stability Program):

• Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerised technology that improves a vehicle's stability by detecting and reducing loss of traction (skidding). 

  

 Wheel-speed sensors: One wheel-speed sensor at each wheel measures the speed    of the wheel which the computer can then compare to the speed of the engine.

Steering-angle sensors:This sensor, in the steering column, measures the direction the driver intends to aim the car. If it's different than the direction the car is actually travelling, the ESC system will kick in. 

Rotational-speed sensor:This is also known as the yaw sensor. It's the one in the middle of the car that measures the side-to-side motion of the vehicle.

• Under steer happens when the front wheels don't have enough traction and the car continues moving forward rather than turning. Oversteer is just the opposite: the car turns farther than the driver intended causing the rear wheels to slide and the car to spin. ESC, as electronic stability control is often known, can help correct both of these situations.

• The electronic stability control system doesn't work all alone .it uses the car's other safety and regulatory devices, like anti-lock braking and traction control, to correct problems before they become accidents.

• Yaw sensor is there to sense the yawing moment.If the ESC system detects that the car is swinging too far (or not far enough) around that up-and-down axis, it springs into action to assist.

• The ESC will activate one or more individual brakes, depending on which wheel can increase driving safety the most, and control the throttle to lessen the speed at which the car is traveling.

• The sensor is looking for differences between the direction of the steering wheel and the direction the car is headed; the car's computer then makes the necessary corrections to bring the vehicle's direction of travel in line with what the driver wanted. 

3)Anti-lock braking system:

•       An anti-lock braking system (ABS)  is a safety system on motor vehicles which prevents the wheels from locking while braking.

•       The Anti-lock Braking System is designed to maintain vehicle control, directional stability and optimum deceleration under severe braking conditions on most road surfaces

•       It does so by monitoring the rotational speed of each wheel and controlling the brake line pressure to each wheel during braking. This prevents the wheels from locking up.
•       A rotating road wheel allows the driver to maintain steering control under heavy braking.

Need for ABS

•       Maintains vehicle stability and steering control

•       Reduce stopping distance on slippery roads

•       Reduces wear of tyres

•       Avoid skidding while braking 

Components of abs

•       Wheel speed sensors

•       Ecu

•       Hydraulic modulator

•        pump

 

•  Anti-lock braking system (ABS) is an automobile safety system that allows the wheels on a motor vehicle to maintain contact with the road surface according to driver inputs while braking, preventing the wheels from locking up (ceasing rotation) and avoiding uncontrolled skidding.

• ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces; however, on loose gravel or snow-covered surfaces, ABS can significantly increase braking distance, although still improving vehicle control.

          ABS brake system are

•       Integrated(An integrated system has the master cylinder and control valve assembly made together).

•       Nonintegrated(A nonintegrated has the master cylinder and control valve assembly made separate).

WORKING:

• ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics.  

Speed sensors

• A speed sensor is used to determine the acceleration or deceleration of the wheel. 

Valves

• There is a valve in the brake line of each brake controlled by the ABS.This valve is to allow or control the brake fluid to the  brakes.

Pump

• The pump in the ABS is used to restore the pressure to the hydraulic brakes after the valves have released it.

Controller

• The controller is an ECU type unit in the car which receives information from each individual wheel speed sensor, in turn if a wheel loses traction the signal is sent to the controller, the controller will then limit the brake force (EBD) and activate the ABS  modulator which actuates the braking valves on and off.

• The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster.

•  Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation.

• Some anti-lock systems can apply or release braking pressure 15 times per second.

      Open and closed systems:

Open anti-lock system : The brake fluid released from the brakes during ABS stop is not returned to the brake  instead, the fluid is stored  in an accumulator during the ABS stop, then returned to the master cylinder reservoir afterwards.This type is used in simple-rear wheel-only ABS designs.

 Closed system: Closed system has some means, generally an electrically powered   pump, to restore hydraulic pressure that's bled off during an ABS stop. The pump   supplies fluid to an accumulator, where it's stored under pressure until is needed to     increase brake line pressure.

      

     ABS types:

    Four-channel, four-sensor ABS

There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.

    Three-channel, four-sensor ABS

There is a speed sensor on all four wheels and a separate valve for each of the front wheels, but only one valve for both of the rear wheels. Older vehicles with four-wheel ABS usually use this type.

    Three-channel, three-sensor ABS

This scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force.

    Two-channel, four sensor ABS

This system, commonly found on passenger cars from the late '80s through early 2000s uses a speed sensor at each wheel, with one control valve each for the front and rear wheels as a pair.

    One-channel, one-sensor ABS

This system is commonly found on pickup trucks with rear-wheel ABS. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in.

 Advantages Of ABS

• ABS will not decrease a vehicle’s stopping distance compared to an identical vehicle without ABS, it ensures that the shortest distance in which a vehicle can be brought to rest is achieved. It is particularly effective in doing this on surfaces which are wet or icy upon which a vehicle is much more likely to skid.
• The main benefit of ABS is the control that a driver has over the vehicle’s steering. In an emergency the driver of a vehicle equipped with ABS will have a better chance of steering around the obstacle due to the reduced risk of skidding.                                 

Disadvantages

•       Increased braking distances under some limited circumstances (snow, gravel, "soft" surfaces),

•       Creation of a "false sense of security" among drivers who do not understand the operation, and limitations of ABS.

•       The anti-lock brakes are more sensitive on the damper condition. the influence of the worn components on the performance of the vehicle with anti-lock brakes is more significant than without anti-lock brakes, the stopping distance with defective shocks is by meters.

4)Traction Control systems: 

 

 

This system optimise grip and stability of the car on the road during acceleration by measuring wheel rotation. It stops wheel spin by reducing engine power or temporarily applying the brakes to that wheel, allowing the car to accelerate smoothly, even on slippery surfaces.

   electronic traction control. In modern vehicles, traction-control systems utilize the same wheel-speed sensors employed by the anti lock braking system. These sensors measure differences in rotational speed to determine if the wheels that are receiving power have lost traction.

 When the traction-control system determines that one wheel is spinning more quickly than the others, it automatically "pumps" the brake to that wheel to reduce its speed and lessen wheel slip. In most cases, individual wheel braking is enough to control wheel slip. 

However, some traction-control systems also reduce engine power to the slipping wheels. On a few of these vehicles, drivers may sense pulsations of the gas pedal when the system is reducing engine power much like a brake pedal pulsates when the anti lock braking system is working.

                                                                                                                                

Many people mistakenly believe that traction control will prevent their vehicle from getting stuck in the snow. Traction control does not have the ability to increase traction; it just attempts to prevent a vehicle's wheels from spinning. 

                               

5) Adaptive cruise control: 

• Adaptive Cruise Control (ACC) is an automotive feature that allows a vehicle's cruise control system to adapt the vehicle's speed to the traffic environment.

• A radar system attached to the front of the vehicle is used to detect whether slower moving vehicles are in the ACC vehicle's path. If a slower moving vehicle is detected, the ACC system will slow the vehicle down and control the clearance, or time gap, between the ACC vehicle and the forward vehicle.

• If the system detects that the forward vehicle is no longer in the ACC vehicle's path, the ACC system will accelerate the vehicle back to its set cruise control speed. This operation allows the ACC vehicle to autonomously slow down and speed up with traffic without intervention from the driver. 

• The method by which the ACC vehicle's speed is controlled is via engine throttle control and limited brake operation. 

 


 

                              

ACC Module – The primary function of the ACC module is to process the radar information and determine if a forward vehicle is present. When the ACC system is in 'time gap control', it sends information to the Engine Control and Brake Control modules to control the clearance between the ACC Vehicle and the Target Vehicle.

Engine Control Module – The primary function of the Engine Control Module is to receive

information from the ACC module and Instrument Cluster and control the vehicle's speed based on this information. The Engine Control Module controls vehicle speed by controlling the engine's throttle.

Brake Control Module – The primary function of the Brake Control Module is to determine

vehicle speed via each wheel and to decelerate the vehicle by applying the brakes when

requested by the ACC Module. The braking system is hydraulic with electronic  enhancement, such as an ABS brake system.

Instrument Cluster – The primary function of the Instrument Cluster is to process the Cruise Switches and send their information to the ACC and Engine Control Modules. The Instrument Cluster also displays text messages and telltales for the driver so that the driver has information regarding the state of the ACC system.

CAN – The Controller Area Network (CAN) is an automotive standard network that utilizes a 2 wire bus to transmit and receive data. 

Cruise Switches – The Cruise Switches are mounted on the steering wheel and have several buttons which allow the driver to command operation of the ACC system.

6)Lane departure warning systems:

• Lane departure warning system is a mechanism designed to warn a driver when the vehicle begins to move out of its lane (unless a turn signal is on in that direction) on freeways and arterial roads.
• Adaptive cruise control pacing you against the car in front, lane departure warning or lane keep assist watching ahead and to the side.

     Types

Lane departure warning. It is a warning only. When the car drift near, onto, or over the lane marking, the car alerts the driver. The drive has to take corrective action by steering the car back to the middle of the lane. It doesn’t work if the road has no lane markings or lane markings are faded. If it’s raining or snowing, the camera may have trouble, too. By design, the lane departure warning system doesn’t alert, if turn signal is on, or (some cars) if when brakes are applied.

Lane keep assist. This helps when the car is drifted too far. The car then steers itself away from the lane marking. The driver has to re-center the car in the lane. It’s also called lane keeping system, lane assist, side assist (Audi),  lane departure alert with steering assist (Toyota), or lane departure prevention (LDP is sometimes applied also to lane centering assist).

Lane Centering Assist (LCA) - This is the most invasive form of the technology. Rather than providing a warning, or kicking in only when the vehicle drifts toward the edge of its lane, this type of system is actually capable of keeping a vehicle centered in its lane at all times.

• The most common LDW system is a camera mounted high up in the windshield (photo above), often as part of the rear view mirror mounting block. It captures a moving view of the road ahead. The digitized image is parsed for straight or dashed lines — the lane markings. 

•  As the car deviates and approaches or reaches the lane marking, the driver gets a warning: a visual alert plus either an audible tone, a vibration in the steering wheel, or a vibration in the seat. If the turn signal is on, the car assumes the driver is intentionally crossing over the lane, and there’s no alert. That’s lane departure warning. 

• Sometimes the steering change is effected by braking the opposite front wheel and the car pivots back into the lane. The car can also move the car back by turning the steering wheel. In either case, the driver can easily overcome the car’s intentions by turning the wheel.

Laser radar to Measure Vehicle Distance

Laser radar utilizes a laser beam to determine the distance to the measuring object.

The pulse method is used more frequently in low priced, compact systems. the pulse method measures distances by calculating the reciprocating time of light pulses between the objects.

It can be expressed in the following formula of

R = C *Τ/2,

where C represents the speed of light,

Τ represents the reciprocating time and

R represents the distance.

7)Tire pressure monitoring systems or Deflation Detection Systems:

• A tire pressure monitoring system (TPMS) is an electronic system designed to monitor the air pressure inside the pneumatic tires on various types of vehicles. TPMS report real-time tire-pressure information to the driver of the vehicle, either via a gauge, a pictogram display, or a simple low-pressure warning light. 

TPMS can be divided into two different types.

1. Direct (DTPMS) 

2. Indirect (ITPMS).

1.Direct tire pressure monitoring systems uses individual sensors inside each tire.The sensors read internal pressure, and sometimes temperature. The information received at the module is analyzed, and any issues with any of the tires are sent to the car's vehicle information system, or low-pressure light.

Information is most often sent wirelessly as a radio signal. While some systems are mounted outside the tire. Each sensor has a battery with a life of about a decade. On most, the battery is not serviceable, and the entire sensor must be changed.  

A direct TPMS sensor consists of the following components

• pressure sensor
• analog-digital converter
• micro controller
• system controller
• oscillator
• radio frequency transmitter
• low frequency receiver, and
• voltage regulator (battery management).

2.Indirect tire pressure monitoring systems don't rely on sensors to do the work, or at least not pressure sensors. The systems rely on wheel speed sensor data to interpret the size of a tire based on how fast it rotates, a small tire would rotate faster than a larger tire, and an underinflated tire is smaller than one with proper inflation. All of this data can be gleaned by electronic monitors within in the car, and then interpreted using advanced programming and processing.

 

8)Automotive night vision:

•   An automotive night vision system uses a thermographic camera to increase a driver's perception and seeing distance in darkness or poor weather beyond the reach of the vehicle's headlights. 

                                       

                                     

  1)passive night vision system:

• Night vision systems use an infrared sensor typically in the grille to look for warm objects in the roadway. The sensor is a video camera that captures the infrared spectrum just above visible light. The sensor outputs the moving image to a dashboard display. Increasingly, that’s coupled with sophisticated algorithms that detect humans and large animals, and most recently, that sound an alert. This is the case for all night vision technologies.         

• It measure the heat generated by living objects without the need for additional illumination. Warmer objects show up as lighter images on the car’s LCD display, colder objects show up as dark. In between dark grays are the road and rocks emitting heat from the sun into the evening hours.

• Passive night vision wins hands down for claimed range, up to 1,000 feet or 300 meters. (At 60 mph on a country road, that’s theoretically more than 10 seconds of travel time.) Passive systems work better in rainy and foggy conditions. 

• Passive systems work less effectively at warmer temperatures.

EX:   using in  Lexus LX 470 (windshield), LS (instrument cluster), Mercedes-Benz CL-Class (C216)(instrument cluster)..etc

2)Active night vision system:

• Active night vision systems use an infrared illuminator, sometimes part of the headlamp cluster, to light up the road in the IR spectrum. The image can be higher-resolution than passive. Roads and buildings show up better. That’s why drivers initially think they’re watching black and white TV of the road ahead.

• As with normal headlamps, the range of active night vision systems is reduced in rain, snow or fog, and effectiveness falls off with the square of the distance. The biggest drawback with active NV is range, an estimated 500-650 feet or 150-200 meters.   

9)Emergency brake assist:

Emergency brake assist (EBA) or Brake Assist (BA or BAS) is an automobile braking technology that increases braking pressure in an emergency situation.

   

• Electronic brake assist systems use an electronic control unit (ECU) that compares instances of braking to pre-set thresholds. If a driver pushes the brake down hard enough and fast enough to surpass this threshold, the ECU will determine that there is an emergency and boosts braking power. Many of these systems are adaptable, which means they will compile information about a driver’s particular braking style and tweak the thresholds to ensure the highest accuracy in emergency-situation detection.

• Older vehicles that do not have an ECU can have a mechanical brake assist system put in. Mechanical systems also use pre-set thresholds, but these are set mechanically. This means that they are not adaptable to individual drivers. These systems include a locking mechanism that activates when the valve stroke – which is directly related to how far the brake pedal is pushed – passes a critical point. Once this threshold is passed, the locking mechanism switches the source of braking power from the brake piston valve to the brake booster, which supplies the braking assistance.

10)Adaptive Highbeam:

• Adaptive Highbeam Assist makes night-time driving even safer. The system adjusts the headlamp range automatically to the distance of oncoming traffic or vehicles in front with their lights on. This provides the driver with the ideal headlamp range at all times, enabling better and earlier recognition of the course of the road, pedestrians or other dangers.

• The Adaptive Highbeam Assist  is based on a camera on the inside of the front windscreen which monitors the traffic situation in front of the car. An intelligent image processing algorithm enables the camera to identify other vehicles and to calculate their distances. 

•  The range of the variably adjustable headlamps is set accordingly and adjusted continuously according to the distance of the vehicle ahead or oncoming traffic.The system is extremely fast, relaying fresh data to the headlamps every 40 milliseconds. On the basis of this information, the headlamps are switched to low beam and the range of the adjustable bi-xenon headlamps in dipped-beam mode is set within a maximum reach of 300 metres and continuously adapted to the prevailing traffic situation.

•  When the system detects that the road ahead is clear, high beam is activated automatically. Adaptive Highbeam Assist in Mercedes-Benz cars is available at speeds of 55 km/h and over. Once it has been switched on it operates fully automatically.

11. Collision avoidance system:

Forward collision warning (FCW) system is an advanced safety technology that monitors a vehicle’s speed, the speed of the vehicle in front of it, and the distance between the vehicles. If vehicles get too close due to the speed of the rear vehicle, the FCW system will warn that driver of an impending crash. It’s important to note that FCW systems do not take full control of the vehicle or keep the driver from operating it.

The Forward Collision Warning (FCW) system uses a radar to detect vehicles or obstacles in front of the car. The system calculates the distance to the object in front and, if the car gets close enough that there is a risk of collision, sounds an alarm and displays a visual alert, prompting the driver to apply the brakes.

It is an advanced safety technology that monitors a vehicle’s speed, the speed of the vehicle in front of it, and the distance between the vehicles. If vehicles get too close due to the speed of the rear vehicle, the FCW system will warn that driver of an impending crash. It’s important to note that FCW systems do not take full control of the vehicle or keep the driver from operating it.

Forward Collision Warning alerts you if an object in your path has suddenly stopped or slowed down, so you can react faster. FCW will significantly reduce the chance of a crash or a fatal accident.

A collision avoidance system, also known as a pre crash system, forward collision warning system, or collision mitigating system, is an automobile safety system designed to prevent or reduce the severity of a collision. It uses radar (all-weather) and sometimes laser (LIDAR) and camera (employing image recognition) to detect an imminent crash. GPSsensors can detect fixed dangers such as approaching stop signs through a location database.

Once an impending collision is detected, these systems provide a warning to the driver. When the collision becomes imminent, they take action autonomously without any driver input (by braking or steering or both). Collision avoidance by braking is appropriate at low vehicle speeds (e.g. below 50 km/h (31 mph)), while collision avoidance by steering may be more appropriate at higher vehicle speeds if lanes are clear. Cars with collision avoidance may also be equipped with adaptive cruise control, using the same forward-looking sensors.

Radar or Lidar Monitoring

 

 

The radar unit sends out waves that bounce off of surfaces (cars, trucks, bicycles, pedestrians, etc.) and return back to the vehicle’s forward-mounted sensor.

As fast as these radio waves are, they still take a little bit of time to travel from one place to another, so the collision avoidance system can use the time it takes for the waves to bounce back to calculate distance—in this case, the distance from the car to whatever is in front of it. This allows the system to give a visual (flashing lights) and audible (beeping alarm) warning signal if the car is getting too close to something ahead of car.

On some systems, radar pings are sent 20 times per second, allowing it to warn of split-second changes in traffic.

12. On Board Diagnostic (OBD)

OBD is a computer-based system originally designed to reduce emissions by monitoring the performance of major engine components. The OBD system is an on-board computer that communicates with other systems, including the ECU, TCU and more. A basic OBD system consists of an ECU (Electronic Control Unit), which uses input from various sensors (e.g., oxygen sensors) to control the actuators (e.g., fuel injectors)  to get the desired performance.  The “Check Engine” light, also known as the MIL (Malfunction Indicator Light), provides an early warning of malfunctions to the vehicle owner.

Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle. A modern vehicle can support hundreds of parameters, which can be accessed via the DLC (Diagnostic Link Connector) using a device called a scan tool.

The OBD require that all components and subsystems which have an emission impact and which are connected to an Engine Control Unit (ECU) need to be monitored and diagnosed. The components can be divided into:

• Sensors: O2 sensor, temperature sensors, pressure sensors, etc.
• Actuators: Fuel injectors, ignition coils, throttle blades, cam phasers, EGR valve, etc.

On the system side, several subsystems have to be monitored such as a malfunction of a complete subsystem which leads to a certain emission increase. Such subsystems are:

• Fuel Injection System
• Ignition system
• Exhaust gas cleaning system
• Canister purge system

When the OBD system identifies an issue, it turns on a warning light in the dash (generally, the Check Engine Light), and then stores a trouble code (called a DTC, or diagnostic trouble code). A mechanic can connect a scan tool to the OBD II connector under the dash and read this code. 

13. Anti Theft Alarm:

An 'Anti-theft alarm system' or Car Alarm is a type of device or method which alerts when there is an unauthorized access to a motorcycle or car. 

The Anti-theft alarm system works with the help of sensors installed in and around the vehicle. An impact or the movements inside the car activates the sensors. This, in turn, triggers the Anti-theft alarm system and sounds the alarm. The alarm goes off and alerts the owner/people. Even, the change in vehicle’s position can alert the tilt sensor and activates the anti-theft alarm system. 

Car-alarm Transmitters
Most car alarm systems comes with a portable keychain transmitter. With this device, we can send instructions to the brain to control the alarm system remotely.

Shock Sensor 
Shock sensor alarms run on the concept of motion strength. Signals to the brain of the system by the sensors determine the strength of the motion and can detect whether someone is trying to push or hit or move the car. The brain of the system immediately gets the horn honking or activates the audio system to start playing loudly in order to alert.

Motion and Tilt Sensor
This is another type of sensor alarm system which is used to alert from towing away the car between places. Perimeter Scanners are installed in these sensor systems, which are used in order to watch the car's surroundings.The most common perimeter scanner is a basic radar system, consisting of a radio transmitter and receiver. The transmitter sends out radio signals and the receiver monitors the signal reflections that come back. Based on this information, the radar device can determine the proximity of any surrounding object.

Pressure Sensor
This type of sensor system checks and monitors the changes experienced in air pressure created when a window is broken or cars doors are forcibly opened. When a suspicious pressure change is detected, the alarm is triggered. Some pressure sensors employ the in-built speakers of the car, while many others have their own speakers.

Window Sensor
Without the doors of a car being meddled with, a car can still be stolen by just breaking the windows. This is a trick used by thieves many a time. To prevent such a theft, window sensor alarms are used. The basic window sensor alarm can detect glass or window breakage, using a microphone to pick up the sound of breaking glass.
Breaking glass has its own distinctive sound frequency (pattern of air-pressure fluctuations). The microphone converts this to an electrical current of that particular frequency, which it sends to the brain.

Door Sensor
The door sensor alarm is probably the simplest of all car alarms. When the front trunk or doors of the car open, the system gets activated and the alarms start ringing. Most car alarm systems utilize the switching mechanism that is already built into the doors. In modern cars, opening a door or trunk turns on the inside lights.

14. Engine Immobiliser

An Immobiliser or the Engine Immobiliser is an electronic security device which the modern cars use. The Engine Immobiliser uses an electronic chip embedded into the ECU of the vehicle.

An immobiliser is an electronic anti-theft security device which prevents engine start by an unauthorised person unless the correct key or fob is placed in the ignition barrel. If the correct key is used, transponder inside the key sends a signal to the reader which transfer signal to the receiver (ECU). If the signal is recognised by the ECU, the system allows user to start engine. If not the immobiliser disables few car systems that is necessary to start the engine. The ECU does NOT activate the fuel system and the ignition circuit if the code in the key & that stored in the immobilizer does not match.

The immobiliser is strongly connected to the car security system, so any unauthorised access to the car that is detected by the security system (movement detectors, infra-red sensor, sonic sensor and many others, depending on the security system) automatically trigger the immobiliser and any other alarm aims such a horn and flashing headlights.
Car alarm can be activated by infra-red signal generated by the fob or a key ring and received by optical sensing unit placed in the car. 

Another type is a radio control system. Radio wave is created by the fob or the key and received by car antenna. In both examples the signal is unique for each car and only this one signal is recognised by the ECU.
Alarm system uses few different types of sensors to protect the car:
Shock sensor: detecting any vehicle moment
Ultrasonic: car interior is covered by an ultrasonic signal; any change in the strength on the signal pattern activates the alarm
voltage drop or current drain: any drop of voltage (disconnecting the battery) or current drain (by switching on interior light)
Infra-red: detecting any disruption of the beam transmitted between two points inside of the car
Direct earth contact: detected by the bonnet, boot and door switches when an earth contact happens

15. Voice warning system

It on the contrary brings in some problems such as the happenings of accidents due to driver’s fatigue after a long journey of travel, the shortage of parking spaces, the bad visibility in night or the driving in heavy rain days etc. A voice warning system for automobiles includes a microprocessor connected with the battery of an automobile, a plurality of sensors arranged on different parts of the engine and connected with the microprocessor, and two voice integrated circuits for storing voice messages, whereby the microprocessor will give voice messages to notify the driver of the conditions of the car thereby ensuring the safety of the driver.

A voice warning system for an automotive vehicle comprising:

    1. A plurality of sensors for detecting various abnormal conditions in an automotive vehicle, for outputting voice warning information in response to said sensors when one of said sensors detects an abnormal condition

    2. A relay for reducing to an audible level lower than an initial audible level an audio signal level sent from other audio equipment provided within the same vehicle so as not to interfere with the voice warning information, said means for reducing the audio signal level being activated by a signal sent from any one of said sensors, whereby the driver can hear the voice warning information clearly even when the audio equipment is operating.

A voice warning system process the following information

an engine oil indicator lamp sensing

an engine speed sensor

an engine speed sensing interface

an engine speed sensing

a door positive sensing interface

a hand brake sensing interface

an engine oil sensing interface

an engine temperature sensor

a gasoline sensing interface

a brake oil level detector

an engine oil mileage interface

an automatic transmission fluid mileage interface

Keyless Entry system

 

A remote keyless entry system consists of a remote, which, when activated within a certain range, can lock, unlock and perform various other functions within a car. Such a remote consists of a short-range radio transmitter that sends radio waves to a receiver unit inside the car, which triggers the aforementioned functions.

 The tiny ‘car remote’ for any car consists of a short-range radio transmitter. When the remote is within a specific range (typically, 5-20 meters) from car, press one of its buttons, a coded signal, embedded in radio waves, is sent to a receiver unit installed inside the car. The receiver unit then decodes and translates that signal, which consequently locks/unlocks the doors, trunk of the car.

 

Passive Key less Entry

A remote of this category is commonly referred to as a smart key (also called an ‘advanced key’ or ‘hands-free’ key).

Unlike regular Remote key entry, PKE devices don’t typically require to push any buttons to lock/unlock the car. This is because, in addition to a radio transmitter, it also contains a receiver. The transponder (a combination of the words ‘transmitter’ and ‘responder’) inside the smart key doesn’t need a battery to work.

It allows the user to keep the key fob in their pocket while approaching the car, as the transponder inside the fob communicates with the receiver system of the car to open the doors and even activate the ignition from a distance. Furthermore, it does the latter without requiring the user to put the key in the ignition. To lock the car, the user can press a button on one of the door handles, touch a capacitive area on a door handle, or simply walk away from the car.

 

Central locking system

Power door locks (also known as electric door locks or central locking) allow the driver or front passenger to simultaneously lock or unlock all the doors of an automobile or truck, by pressing a button or flipping a switch.

Today, many cars with power door locks also have a radio frequency remote keyless system, which allows a person to press a button on a remote control key fob. It allows the windows to be opened or closed by pressing and holding a button on the remote control key fob, or by inserting the ignition key and holding it in the lock or unlock position in the external driver's door lock. The remote locking system confirms successful locking and unlocking through either a light or a horn signal.

 Door assembly consists of catch, pawl and latch. The door lock striker is attached to the body pillar. Under closing operation the door lock striker gets caught by the latch and hold in the closed position and centres the door. The pawl positively locks the catch in position. This lock condition is automatically aborted when opening procedures begin. For this process the forces acting on inner or outer door handle are transferred to the pawl and cause the catch release to open the door. The door lock striker stays in the position while the catch swivels go into an open position.

In a case of operation methods central locking system consists of two types of actuators: electromagnetic and pneumatic

Electromagnetic actuators rely on solenoids which lock or unlock doors using current going in both directions (open/closed) through an electric module. On this kind of system two types of arrangements are in use. First one uses separate relays for each of action taking by the system. One dedicated to open and another one to close the door. Both of them are controlled by a transistor switching the circuit operated by the capacitor (storage for energy necessary to operate system) which is releasing current necessary to activate the locks. Another type uses two capacitors and two relays working as a tandem. One pair is responsible for locking and another for unlocking. When the circuit is closed a current is discharged from the capacitor and the lock is either opened or closed.

Pneumatic actuators are driven by a pneumatic central unit which controls vacuum/pressure pump. When vacuum is applied actuators acting on mechanism lock or unlock the door. The vacuum pump is driven by electric motor which is working in both directions. Forward rotation creates a compressor action (doors open), while backwards rotation creates vacuum (doors close). Polarity on the electric motor is changed by a change-over control switch.

In most modern cars electrical locking system replaced mechanical unit due to a demand for quality and reliability.

 

 

 The main advantages of electrical locking system are:

• symmetrical design,
• smaller and lighter in comparison to a mechanical unit
• only one lock version per vehicle
• individually encoding at the end of the production line
• door handles no longer move
• Other supplementary functions, like an interior light or status indicator, can be easily introduced in electrical locking system because the lock is equipped with electronics, which can carry out these functions. Communications with the locks, power supply and security system take place via data can bus system.

Blindspot detection

The system is also called blind spot detection, blind spot monitoring, and blind spot information system. Blind spots are the areas outside of a vehicle that the driver is unable to see. Blind spots can be caused by the window pillars, headrests, passengers, and other objects.

While driving every part of the car that isn't glass creates a blind spot. That means vehicles with larger window pillars have larger blind spots, vehicles with smaller rear view windows have larger blind spots, and both cargo and passengers can also create additional blind spots.

Blind spots are relatively small close to a vehicle, but they cover larger areas further away. At even moderate distances, a blind spot  caused by an A-pillar can obscure large objects such as cars and people. Another type of vehicular blind spot exists in the space between the driver’s peripheral vision and the area reflected by the rear-view mirrors. This type of blind spot can swallow up entire vehicles, which is why it's so dangerous to change lanes without looking to the left or right.

Blind spot detection is a key technology among driver aids that provide 360 degrees of electronic coverage around the car. This circle of safety also includes adaptive cruise control, lane departure warning, rear and front parking sonar, the rear traffic alert, and parking cameras (ranging from rear-only through four cameras providing a birds-eye view of the car.

All active systems, whether they use lasers, radars, or cameras, constantly monitor the spaces around the vehicle. If they detect a vehicle in the car’s blind spot, they pass a message to the driver, usually in the form of an indicator light on either the dashboard or the side view mirrors or on the inside of the front roof pillar nearest the mirror, or on an adjacent window frame. Some systems also give the driver an audio warning if the turn signal is activated when the blind spot monitor has been triggered. The most sophisticated systems have some ability to intervene and prevent the driver from merging into another lane when another vehicle is detected in the blind spot.

The first such system was developed by Volvo Cars and deployed in 2003. 
It used cameras placed in the car's side rear view mirrors, and a computer processed the image from those cameras to see if anything looked like a car and seemed to be approaching dangerously into the area where the car might hit it while changing lanes.

In other types, use radar (electromagnetic waves that bounce off solid objects and return an echo indicating if they're there) and are mounted in the rear of the car, in the vicinity of the back bumpers. These sensors are valued for both their fast response time and their wide effective range which emits a 360-degree wave.The Blind Spot Intervention (BSI) System of Infinity will start gently applying the brakes on the side of the car away from the danger, causing the vehicle to slowly swerve back toward the safe lane. Audi's BLIS, will detect cars.

Rear view cameras

  

Rear view cameras, often part of parking assistance systems or parking guidance systems, are an indirect type of blind spot monitoring system. Typically, these systems send a video feed of the rear of the vehicle to a display in the center console of the vehicle, giving the driver a sharp, unobstructed view of the rear of their vehicle and all of the potential obstacles and vehicles behind them.

Automotive Navigation Systems:


Automotive navigation system is used in in-vehicle infotainment systems. Automotive navigation system uses satellite navigation technique. Navigation systems use top view for the map. These systems use global positioning system (GPS) to facilitateintelligent navigation.

 1. GLOBAL POSITIONING SYSTEM (GPS):

GPS is used to find the systems current position. It helps in determining the co-ordinates (longitude and latitude) of the system’s position. These co-ordinates are mapped to the unit maps database which helps in determination of the system’s location.

 

Satellite Navigation is based on a global network of satellites that transmit radio signals in medium earth orbit. The basic GPS service provides users with approximately 7.8 meter accuracy, 95% of the time, anywhere on or near the surface of the earth. To accomplish this, each of the 32 satellites emits signals to receivers that determine their location by computing the difference between the time that a signal is sent and the time it is received. GPS satellites carry atomic clocks that provide extremely accurate time. The time information is placed in the codes broadcast by the satellite so that a receiver can continuously determine the time the signal was broadcast. The signal contains data that a receiver uses to compute the locations of the satellites and to make other adjustments needed for accurate positioning. The receiver uses the time difference between the time of signal reception and the broadcast time to compute the distance, or range from the receiver to the satellite.

With information about the ranges to three satellites and the location of the satellite when the signal was sent, the receiver can compute its own three-dimensional position. An atomic clock synchronized to GPS is required in order to compute ranges from these three signals. However, by taking a measurement from a fourth satellite, the receiver avoids the need for an atomic clock. Thus, the receiver uses four satellites to compute latitude, longitude, altitude, and time.

Infotainment systems

The infotainment system can be described as a distributed, heterogeneous hardware/software system, which provides entertainment functionalities and information services to the drivers and passengers in the vehicle through the interaction of several connected devices. It mainly comprises of a head unit along with a combination of components such as a control panel, telematics device, and head-up display. The hardware components are interconnected with certain standardized communication protocols such as CAN network  (CAN network or controller area network is a robust vehicle bus standard and is designed to allow microcontrollers and devices to communicate with each other in applications without the host computer.) and some wireless communication channels like Bluetooth. 

 

Head Unit (HU) is regarded as the master of the infotainment network. It contains one or more CPUs for real-time communication purposes (e.g. Infotainment gateway CPU) and at least one for the user interface with infotainment applications (Main CPU).

Infotainment & Multimedia gateway contains a CPU (Gateway CPU) for real-time communication with other peripheral components like memory, CAN transceivers, Media Oriented System Transport (MOST) transceiver, and other components. The gateway CPU is connected to the main CPU with an internal bus. The main CPU is not connected to the MOST command/control channel and the CAN network, so all the messages from the main CPU to end user are sent and received over the gateway CPU.

 IVI System Framework

 

In-vehicle infotainment system comprises of the following services:

I) Entertainment Services: 

Audio: The audio runs through radio, CD player, or by playing tracks with USB or phone connectivity; it may support MP3 or WMA format based on the OS (Operating system).The basic components of the audio systems are speakers, subwoofers, and amplifiers. 

Video: The car should be equipped with an exclusive multimedia system. Today, cars have internet TV and also have an option to access mobile TV. However, there are several challenges such as a power source and signal reception during motion that affect the quality of the pictures or videos.

II) Phone Services:

Enhancing communication Services: The IVI system provides calls and messaging services with a hands-free experience to attend calls while driving. The driver can use Bluetooth headsets to communicate and can also use voice commands to operate the system.

III) Information Services:

This service offers many useful features to protect the car and get information for vehicle safety and ease of driving.
Rear parking assistance: The system can help drivers in getting a better idea about the objects or vehicles at the rear side. It can also facilitate to display the corresponding situation on the screen.

Navigation System: Automotive navigation system is used in IVI systems. This system uses satellite navigation technique to show a top view of the map and provide ease of navigation to drivers.

Vehicle-related Information: This system gives an overall information about the vehicle including:

• Fuel level
• Total distance covered
• Brake fuel level
• Air filter clogged with dust particles
• Door open or close
•  

Heating, Ventilation and Air conditioning

HVAC is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality depending on the inputs of the operator as well as electronic sensors.. It is the process of "exchanging" or replacing air in any space to provide high air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air.

Pieces of a Basic HVAC System

Cabin Air Filter

 

These filters make sure only clean air enters the HVAC system.

Heater Blower/Blower Motor

 

The blower motor provides the air movement in the HVAC system. These electronic motors can have an almost infinite number of fan speeds on a system that uses PWM.

Heater Core

 

The heater core is what warms the air up when the temperature is selected. It is basically a mini radiator. It has coolant running through it and transfers heat from the engine coolant to the air in the HVAC system.  

Evaporator Core

 

Any air entering the HVAC system passes through the evaporator core. This is what cools the air when the A/C is activated. 

Evaporator Drain

 

Air can hold more moisture when it is warm than when it is cold, so when air is cooled by the evaporator, the air must give up some of its moisture. This moisture condenses and builds up on the evaporator. The evaporator drain is in place to allow that condensation to drain out onto the road.

 Mode Doors

  

There is usually only 2 mode doors on a simple HVAC system to control where the heated/cooled air ends up. Typical systems have floor vents, upper vents and a defrost vent. 

Blend Door

The blend door is not much different than the mode doors except it controls how much air passes through the heater core. The more air that passes through the heater core, the warmer the air will be at the vents.  

Working

 The recirculation flap, it determines whether air for the HVAC system is taken from outside the cabin or recirculated air from the cabin. Outside air has to pass through a cabin air filter before making its way into the rest of the HVAC system. Outside air is usually taken from under the wiper cowl. 

Next is the blower motor, this determines how hard to blow air into the cabin. After that air passes through the A/C evaporator.  The evaporator core does not absorb heat/cool the air unless the compressor is activated, therefore the evaporator does not need to be bypassed when the A/C is not in use. From there the air comes to the blend door. 

The blend door is typically the most active door. It determines how much air passes through the heater core. The heater core has engine coolant passing through it, so it is hot any time the engine is hot. After the air has been set to the correct temperature, all that is left is to send it to the correct vents. The mode doors are in charge of this and are the last decision that needs to be made by the HVAC system.

Possible Settings

Full Heat

 
In this setting the operator has demanded full heat. 100% of air flow is directed through the heater core by the blend door to deliver the most heat possible to the main upper vents.

In this setting the operator has selected full cold but has left the A/C off by either selecting economy mode or by not selecting A/C on. 100% of the air flow is directed around the heater core to allow filtered air at ambient temperature to enter the cabin through the main upper vents.

Max A/C

 

In this setting the operator has selected max A/C. The A/C compressor engages and the evaporator begins to absorb heat. To get the most cooling power, the HVAC system takes air from the cabin that has already been cooled once and cools it again instead of trying to cool hot ambient air.

Outside Rear View Mirror(ORVM)

1. Internally Adjustable
1. Manual
2. Electrical
2. Externally adjustable
1. Manual

Electronic Outside Rear View Mirror

A conventional power mirror switch is essentially two rocker switches built into a single housing. Each rocker switch is connected to two wires that are connected to a reversible DC (direct current) motor inside the rear view mirror on either door. Each rear view mirror has two DC motors. One DC motor operates the up/down function while the other DC motor operates the left/right function.

Both of the rocker switches inside the power mirror switch are constantly connected to the vehicle’s electrical ground circuit with the switch at rest. When the switch is presses, the switch in any mirror direction, the switch connects one of the two wires of a motor to power (12 volts DC) while keeping the other circuit connected to ground. Electricity then flows through the switch to the DC motor and the mirror head moves in the intended direction. If you press the same switch to the opposite direction, you are reversing the electricity to the mirror motor and the mirror moves in the opposite direction.

 

Nowadays the ORVM are not those simple. It has advanced features which makes driving easy and safe.

 Memory Function : The mirrors work in conjunction with the adjustment of seats.
          Different drivers have different driving adjustments with the seating and hence the
         seats are provided with memory function. Once you press the desired setting the
         seats adjust automatically as per the drivers requirement, along with the exterior
         mirrors which are synchronized with the seat adjustment.

Heating : As we all know the rear windscreen comes with rear demister to remove
         mist and to give clear visibility to driver for rear viewing, nowadays even the ORVM
         come with heating feature which responds automatically to the changes in the        humidity
         level and the temperature, especially in the rainy and winter seasons. Even the side

         view of car is clear now.

  Electric folding: The mirrors can be retracted when negotiating in tight lanes and parking spaces. By just press of a button both the ORVM can be folded inside to make some extra space for the car to move. Also when you lock the car the mirrors get retracted automatically to save itself from any mishap by other vehicle when parked.

Automatic Anti Glare : Exterior mirrors are now fitted with sensors which darken themselves at night in
         response to the headlight dazzle coming from the rear vehicle. The ORVM automatically dim itself
         reducing the glare of the light coming from behind, which helps to avoid driver's distraction. The sensors
         progressively measures the intensity of the rear light and accordingly darkens the mirrors as per the
        ambient light conditions.    

Automatic Tilt : When the driver shifts the gear to reverse the left side mirror automatically tilts downward
         to give driver proper visibility of the left hand side while reversing. The driver car have a view of the roadside to
         rear left wheel to park the car conveniently in tight parking situations.