Safety in Automobiles:
1. Air bags:
It is a safety restraint system of an automobile. It consists of air bags, sensors, inflation system / air bag module unit. The purpose of using an air bag is to cushion occupants during a crash, reduce their speed in collision without getting injured and provide protection to their bodies when they strike interior objects such as the steering wheel or window in passenger compartment. Air bag is made of thin nylon fabric, folded into a steering wheel on dashboard or the door or seat. Sensors are used to trigger the inflation of air bag.
Working of Air bags: During collision a mechanical switch is flipped and an electrical contact takes place. Sensors send an electric current to the air bag module. The impact sensor senses impacts. The sensors are set to a sensitivity level where they will only deploy in an accident that is equal to or greater than a 20 kmph crash into a concrete wall.The sensor functions by detecting automobile deceleration.
When the automobile decelerates at a rapid rate, the sensors are tripped This deceleration detecting is the job of two or more deceleration sensors, placed at the front of the car When the sensors go off, they send an electrical current to the inflation system, causing it to deploy the airbag. The air bag module unit consists of an inflator assembly, a nylon bag and a breakaway cover. Inflation system contains sodium azide and potassium nitrate The electrical current from the sensors travels to the inflator assembly, where it causes a tiny initiator to be fired. This initiator creates a spark which ignites a propellant, which is generally sodium oxide. The reaction creates nitrogen gas. The gas expands quickly and inflation of air bags takes place which literally bursts from its storage site like the steering wheel.
Side air bags are also offered in certain vehicles. It provides protection during side collisions. This prevents the air bag on the undamaged side of the car from inflating Curtain airbags inflate in front of windows to provide passengers better head and neck protection. It is more efficient at tipping and side impacts. Door air bag has more space, allowing for a bigger bag that provides more coverage. Door mounted side air bags deploy in just 5 to 6 milliseconds, Cinders are removed and the gas is cooled through a filtration screen also inside the assembly. The nitrogen gas is what causes the air bag to inflate This inflation occurs in a average of only 30 milliseconds. When an occupant plunges into the air bag, the gas if forced backwards through vents, a process which takes another 45 milliseconds. The whole sequence from initial detection of a crash, until the air bag is fully deployed, happens very quickly. This is to protect those inside of the vehicle. Once an air bag is used, it needs replacement.
2. Automatic Emergency Braking (AEB)
Auto Emergency Braking (AEB) is a feature that alerts a driver to an imminent crash and helps them use the maximum braking capacity of the car. AEB will independently apply brake if the situation becomes critical and no human response is made. AEB comes in three categories:
● Low speed AEB system - works on city streets to detect other vehicles in front of your car to prevent crashes and non-life threatening injuries.
● Higher speed AEB system - scans up to 200 metres ahead using long range radar at higher speeds
● Pedestrian detection system detects pedestrian, object or animal movement in relation to the path of the vehicle to determine the risk of collision.
Front collision warning systems vary between manufacturers - and even models. Some vehicles feature two or more AEB systems. Automatic Emergency Braking is present in many high-end cars Example: Volvo V40.
Working of AEB: AEB uses forward-looking radar, cameras or optical sensors to help driver avoid collisions with other vehicles. AEB continuously monitors the road and automatically applies the brakes if the driver fails to do in a possible crash situation. At speeds between 5-50 kmph, the AEB feature would bring the car to a halt in case a collision is imminent It won't work if you provide feed with the steering or manually apply the brakes to give full control to the driver. It has been designed to prevent an accident if the driver has lost concentration and is not aware of what lies ahead This system can be combined with the Pedestrian Detection system also The Pedestrian Detection system is an optional extra which can identify individuals along the road and will stop an accident from occurring. However, if the accident does oecur. Volvo has a solution for that also. When the car detects that a collision has occurred with a pedestrian, it would lift the hood up just á little and an airbag would be deployed for the pedestrian.
3. Adaptive Cruise Control (ACC)
Adaptive cruise control monitors the speed and distance of the vehicles ahead and automatically adjusts the speed of the car using ACC system to maintain appropriate/safe following distance without driver intervention. ACC system decelerates to speed of vehicle ahead. ACC requires the driver to set the desired travelling speed and will accelerate or decelerate up to that speed depending on the speed of the vehicles in front. It is an extension of the standard cruise control system.
Working of ACC: An ACC equipped vehicle has radar sensor with main controller, brake actuator, accelerator pedal actuator, audible buzzer, actuator controller and indicator. Radar sensor measures the distance to other preceding vehicles (downstream vehicles) on the highway In the absence of preceding vehicles, the ACC vehicle travels at a user-set speed, much like a standard cruise control system. However, if a preceding vehicle is detected on the highway by vehicle's radar, the ACC system determines whether or not the vehicle can continue to travel safely at the desired speed. If the preceding vehicle is too close or traveling too slowly, then the ACC system switches from speed control to spacing control. In spacing control, the ACC vehicle controls the throttle and/ or brakes so as to maintain a desired spacing from the preceding vehicle.
When the danger of a collision is detected, it provides a red warning light that flashes on the windshield. The system provides an audible alert when it senses a reduction in traffic speed in vehicles ahead. Actuators control throttle valve and brake.
The ACC system maintains consistent vehicle performance even in poor visibility conditions, during turns and reduces accidents.
4. Electronic Stability Programme (ESP)
Electronic Stability Programme (ESP) is a computerized technology that improves vehicle's stability by detecting and reducing loss of traction (known as skidding). Some ESP systems also reduce engine power until control is regained. ESP system is designed to stabilize the vehicle during cornering maneuvers.
Electronic stability control works in conjunction with a vehicle's anti-lock braking system (ABS), traction control and electronic power steering system Components of ESP Tube steering wheel angle sensor, yaw rate sensor, lateral acceleration sensor, wheel speed sensor, roll rate sensor and longitudinal acceleration sensor. ESP checks where you are steering and where the vehicle is actually going If there is difference in the direction of steering and vehicle direction of movement, the ESP will intervene in a number of ways. Typically, the vehicle ESP will communicate with Traction control system (TCS)and engine control unit (ECU) to reduce power, if the driver is applying throttle. This helps keep the vehicle from worsening its situation.
ESP decides what wheel to brake applies the brake at individual wheels with varying degrees of pressure and duration ESP also decides whether to reduce engine torque to Stabilize the vehicle. By doing so, the system can help the vehicle correct its path and prevent it from leaving the roadway, straying across a divided highway, or even rolling over. It allows for higher speeds at cornering with reduced skidding or better traction.
Working of ESP: ESP is always active. A microcomputer monitors the signals from the ESP sensors and checks 25 times second, whether the driver's steering input corresponds to the actual direction in which the vehicle is moving. If the vehicle moves in a different direction ESP detects the critical situation and reacts immediately = independently of the driver. It uses the vehicle's braking system to "steer" the vehicle back on track. With these selective braking interventions ESP generates the desired counteracting force, so that the car reacts as the driver intends ESP not only initiates braking intervention, but can also intervene on the engine side to accelerate the driven wheels. So, within the limits of physics, the car is kept safely on the desired track.
5. Anti-collision System
Today's vehicles have high speed and high performance. Due to reasons like human error, misjudging, driving dynamics, weather, distraction, inexperience, tiredness and alcohol - road accidents are increasing As a result various anti-collision systems are designed for safety These systems reduce severity of an accident that may result in loss of lives and/or severe property damages.
Traffic collisions can be classified as follows :
● Head-on
● Road departure
● Rear end
● Side collision
● Rollovers
So, anti-collision systems are designed to avoid all relevant collisions. An anti-collision system generally has camera sensors and radars or laser to detect and warn the driver of any danger lying ahead on the road. The danger could be a car, a pedestrian, an animal, a stationary object such as a pole or tree. Several advanced features like audio warning the driver, pre-charging of brakes, automatic partial or full braking are available to avoid any fatalities.
Following are major emerging anti-collision systems and their purpose.
● Forward collision warning system: uses an electronic system with sensors- cameras, radar or Light detection and ranging (LIDAR) to detect a vehicle or object in the front and warn the driver of possible collision.
● Lane departure warning system: has a camera that tracks the vehicle's position on the land and alerts the driver via warning signal such as steering wheel or seat vibration, when the vehicle steers off its lane.
● Adaptive cruise control: that allows the driver to drive vehicle at the desired speed, in which the system will control vehicle speed as per traffic and maintain safe distance with the leading vehicle
● Automatic braking system: avoids collision by automatically applying a brake on sensing an immediate collision with a nearby vehicle
● Electronic Stability Program: featuring sensors and a microcomputer, it detects and reduces the loss of traction (skidding) of a vehicle, while also applying brake automatically to stabilize the vehicle and help steer the vehicle on the desired path.
● Blind spot monitor system : integrates sensors that monitor vehicle sides for approaching blind spots and warns the driver of any dangers during lane changes or turning.
● Automobile night vision system : uses infrared imaging for enhanced vision in dim lighting or poor weather conditions when headlights fail to reach drivers' viewing distance.
6. Active Passive Integration System
Active System In active systems, pre-emptive measures are taken to reduce the possibility of crashes. Active safety is a design that avoids a risk.
● Passive System: In passive system, reactive measures are taken to reduce severity of injuries Passive safety is a design that minimizes losses when a risk occurs.
The Indian automotive active/passive safety market has been segmented on the basis of safety type, offerings, vehicle category, and end-user. Based on the safety type, the market is segmented into active safety and passive safety.
The active safety segment is further classified into blind spot detection, collision avoidance/warning system, early warning of severe braking ahead, Head Up Displays. Antilock Braking System, electronic stability control, traction control, brake assist, adaptive/autonomous cruise control system, and manual override for central locking system The passive safety segment is classified into seat belts, airbags, crumple zones, and whiplash protection.
On the basis of offerings, the active/passive safety market is segmented into hardware, technologies, and software/solutions. The hardware segment is further classified into devices and sensors & modules. The devices segment is further classified into camera, vision systems,RADAR systems, and ultrasonic systems.
The sensors & modules segment is further classified into image sen thermal sensors, acoustic sensors, ambience sensors, position sensors, gas sensors, inertial sensors, proximity sensors, and others. Based on vehicle category, the active/passive safety market is segmented into passenger cars, LCV, trucks, and buses. Passenger cars are further classified into hatchback, premium hatchback sedan, and SUVs. On the basis of end-user, the Indian automotive active/passive safety market is segmented into personal usage, commercial, and phone usage. The commercial segment is further classified into cargo carriers, passenger carriers, and automotive rental providers.
7.Active Passive Integration:
Active Seatbelt Systems: For example, sensors may detect when a vehicle is following too closely and slow down the vehicle, straighten seat backs, and tighten seat belts, to avoid or prepare for a crash. Active Seatbelt Systems utilize a motor that retracts seat belt webbing in ethical situations before a crash occurs. The active seat belt can be activated using data from active safety systems, such as the Electronic Stability Control or Brake Assist systems. It can iso be triggered by data from environmental sensors, such as radar that provides the relative speed and distance to the vehicles ahead. Once activated, it puts front seat occupants in a better position by keeping them closer to the seat and lessening the forward movement of the body and is a great example of the integration of active and passive safety systems.
2. Early adopter Continental, contends its Active Passive Integration Approach (APIA), which links existing active safety devices such as ABS, Adaptive Cruise Control (ACC) and ESC with passive safety systems such as seatbelts and airbags, can prevent crashes before they occur. APIA enables up to 22 safety components and systems on a car to rapidly exchange data about the activities of the driver, the behavior of the vehicle and the status of the driving environment. For instance, a "closing velocity" sensor detects nearby events or objects that could cause an accident, such as a vehicle ahead suddenly braking.
A "danger control module" computes the hazard potential and, if an accident appears imminent, initiates a staged response to minimize its severity. The driver gets a visual or "haptic* warning (accelerator pedal vibration), seatbelts ure pulled taut, windows and sunroof close automatically, the brake system is pre-pressurized and front seats are brought to the ideal position for airbag deployment.
3. Over time Mercedes-Benz has extended the range of features to include additional functionality, such as the PRE-SAFE impulse side function. Unlike in a frontal collision, there is only a limited crumple zone available in the event of a side impact, so to increase the size of the zone, the occupants in the danger area are moved away from the door and towards the centre of the vehicle just before the impact.
To do this, the system inflates air chambers in the side bolsters of the backrest within a fraction of a second of an imminent side impact being detected. The inflated chamber moves the occupant to the side, away from the danger area and towards the vehicle centre, thus increasing the distance between the passenger and the door.
To further reduce the side-effects of a collision Mercedes-Benz makes use of the body's natural reflex to prepare the occupants' ears for the loud noise experienced during an accident: A muscle in the car, known as the stapedius, reacts to loud noises reflexively by contracting briefly changing the link between the eardrum and the inner ear, thereby providing greater protection against high sound pressures. Mercedes-Benz uses this natural reflex as a biomechanical ear protection for the PRE-SAFE Sound innovation. By emitting a short interference signal through the vehicle's sound system the stapedius' reflex is triggered, which prepares the ears for the noise and thus lessens the risk of hearing discomfort or damage.
So while in the past, road users were expected to take complete responsibility for safety. concepts such Vision Zero are gradually shifting the emphasis of safety to underlying ethical principles that propose it can never be ethically acceptable that people are killed or seriously injured when moving within the road transport system."
Responding to this concept where responsibility is shared by transportation system designers, vehicle manufacturers and road users, OEMS are stepping up to the plate by making sure integrated passive and active systems offer passengers the best protection at all times, whether actively avoiding an accident or using smart integrated systems to limit injury to occupants in the event of an accident
