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ABSTRACT
Currently, vehicles are often equipped with active safety systems to reduce the risk of accidents, many of which occur in the urban environments. The most popular include Antilock Braking Systems (ABS), Traction Control and Stability Control. All these systems employ different types of sensors to constantly monitor the conditions of the vehicle, and respond in an emergency situation.
In this paper the use of ultrasonic sensors in safety systems for controlling the speed of a vehicle is proposed. An intelligent mechatronic system includes an ultrasonic wave emitter provided on the front portion of a car producing and emitting ultrasonic waves frontward in a predetermined distance. An ultrasonic receiver is also placed on the front portion of the car operatively receiving a reflective ultrasonic wave signal.
The reflected wave (detected pulse) gives the distance between the obstacle and the vehicle. Then a microcontroller is used to control the speed of the vehicle based on the detection pulse information to push the brake pedal and apply brake to the car stupendously for safety purpose.
Keywords: ABS, Microcontroller, Pies electric effect, stupendous braking, Ultrasonic sensor, XC60 SUV
INTRODUCTION
Driving is a compulsory activity for most people. People use cars to move from one place to another. The number of vehicles is increasing day by day. It is produced tacked tightly and risk to accident. Nowadays, the numbers of accident is so high and uncertainly. Accidents occur frequently and cause worst damage, serious injury and death. These accidents are mostly caused by delay of the driver to hit the brake.
The number of vehicles is increasing day by day and proportionally the numbers of accidents are also increasing. These accidents are mostly caused by the delay of the driver to hit the brake. To prevent the accidents caused by this delay, Ultrasonic braking system is used in automobiles.
The main target of the ultrasonic braking system is that, cars should automatically brake when the sensors sense the obstacle. This is a technology for automobiles to sense an imminent forward collision with another vehicle or an obstacle, and to brake the car accordingly, which is done by the braking circuit. This system includes two ultrasonic sensors viz. ultrasonic wave emitter and ultrasonic wave receiver.
The ultrasonic wave emitter provided in front portion of an automatic braking car, producing and emitting ultrasonic waves in a predetermined distance in front of the car. Ultrasonic wave receiver is also provided in front portion of the car, receiving the reflected ultrasonic wave signal from the obstacle.
The reflected wave (detection pulse) is measured to get the distance between vehicle and the obstacle. Then PIC microcontroller is used to control the servo motor based on detection pulse information and the servo motor in turn automatically controls the braking of the car.
Thus, this new system is designed to solve the problem where drivers may not be able to brake manually exactly at the required time, but the vehicle can still stop automatically by sensing the obstacles to avoid an accident.
This project is designed to develop a new system that can solve this problem where drivers may not brake manually but the vehicles can stop automatically due to obstacles.
The main target for this project is, cars can run automatic braking due to obstacles when the sensor senses the obstacles. The braking circuit function is to brake the car automatically after received signal from the sensor.
LITERATURE SURVEY
The existing approaches in preventing accidents are: Honda’s idea of ABS (Anti-lock Braking System) which helps the rider get a hassle free braking experience in muddy and watery surfaces by applying a distributed braking and prevents skidding and wheel locking. Volvo is all set to launch its new XC60 SUV which will sport laser assisted braking which will be capable to sense a collision up to 50 mph and apply brakes automatically.
William K. Lennon (1999) explains that there exist several problems in the control of brake systems including the development of control logic for antilock braking systems (ABS) and “base-braking.” Here, we study the base-braking control problem where we seek to develop controller that can ensure that the braking torque commanded by the driver will be achieved. In particular, we develop a “fuzzy model reference learning controller,”
a “genetic model reference adaptive controller,” and a “general genetic adaptive controller, “and investigate their ability to reduce the effects of variations in the process due to temperature.
Diva P (2015) provides an efficient way to design an automatic car braking system using Fuzzy Logic. The system could avoid accidents caused by the delays in driver reaction times at critical situations. The proposed Fuzzy Logic Controller is able to brake a car when the car approaches for an obstacle in the very near range. Collision avoidance is achieved by steering the car if the obstacle is in the tolerable range and hence there is no necessity to apply the brakes. Another FLC (which is cascaded with the first FLC for collision avoidance) implements the Anti-lock Braking capability during heavy braking condition.
Thus the system is made intelligent since it could take decisions automatically depending upon the inputs from ultrasonic sensors. A simulative study is done using MATLAB and Lab VIEW software. The results obtained by the simulation model are compared with the existing system and the proposed model conveys a satisfactory result which has high consumer acceptance. AT Mega controller is used for implementation of the proposed system.
Keung So Kim (2009) describes that the auto-braking system was designed by VHDL and fabricated to keep a distance between two cars. It provides pre-crash safety system for intelligent car. This module can detect the distance between front vehicle and driver’s vehicle to keep a constant distance using a sensor and operate the brake system forcibly if the driver does not decrease the speed of car. The system displays the distance between the two vehicles and the speed of your vehicle. The performance of the system was good.
DRAWBACKS IN THE EXISTING APPROCHES:
• ABS can only help if the rider applies it in the right time manually and maintains the distance calculations. ABS has its own braking distance.
• Moreover many commuter bikes in India don’t have the option of ABS because it’s very expensive.
• Volvo’s laser assisted braking could not work effectively in rainfall and snowfall season and laser is easily affected by atmospheric conditions.
In our project we are using Ultrasonic sensors and Microcontroller using which the speed of the vehicle is automatically reduced and voice alarms are given to the user when it approaches an object by automatically sensing the position of the object/vehicle.
There are two cases which occur in real situations:
I. The distance between the front car and the driver’s car is far enough to defend crashing, and the self-velocity is the same as velocity of front car or slower than that of front car. In this case, the driver’s car continues to run without changing its velocity.
ii. Another case is that the distance between the front car and driver’s car is less than the required safe distance at that velocity. Then the auto-braking system
Forcibly reduces the speed of the driver’s car and eventually the car stops to prevent an accident.
The proposed system exhibits four levels of operations
I. The first level is the high speed operation, above 90km/hr. In this case the safety distance that must be maintained in between the vehicle and the obstacle is considered as 5 meter. Thus, if the sensors detect any obstacle or vehicle within this range the brake is applied automatically and the speed is reduced. As the obstacle is moving away the driver can increase speed manually.
ii. The second level is the medium speed operation, between 60km/hr and 90km/hr. In this case the safety distance that must be maintained in between the vehicle and the obstacle is considered as 4 meter. Thus, if the sensors detect any obstacle or vehicle within this range, the speed is automatically reduced.
iii. The third level is the low speed operation, between 30km/hr and 60km/hr. In this case the safety distance that must be maintained in between the vehicle and the obstacle is considered as 2 meter. Thus, if the sensors detect any obstacle or vehicle within this range, the speed is automatically reduced.
iv. The fourth level is the very low speed operation, below 30km/hr. In this case the safety distance that must be maintained in between the vehicle and the obstacle is considered as 1 meter. Thus, if the sensors detect any obstacle or vehicle within this range, the speed is automatically reduced.
COMPONENTS AND DESCRIPTION
Material’s used
1. Ultrasonic sensor
2. Braking unit
3. Pneumatic cylinder
Supplying compressed air
A bicycle pump can produce compressed air. This is all right for inflating the tires on your bicycle, but can you imagine trying to blow up all the tires on a lorry using this? You would soon become tired, exhausted even.
In order to supply pneumatic systems with compressed air we use a machine called a compressor. Compressors come in lots of different shapes and sizes but they all work in the same way.
A pump that is driven by a motor sucks in air from the room and stores it in a tank called the receiver. You will be able to hear the compressor when it is running. Sometimes though, it will stop because the receiver is full.
Not everyone in your class could connect directly to the compressor, as this is not practical. Instead, a pipe takes the compressed air from the receiver to various points around the room. We would normally connect a device called a manifold to these points. The manifold lets us connect lots of components to the compressed air. It also lets us switch our circuits on and off
Air Compressor
An air compressor is a device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure. When tank pressure reaches its upper limit the air compressor shuts off. The compressed air, then, is held in the tank until called into use. The energy contained in the compressed air can be used for a variety of applications, utilizing the kinetic energy of the air as it is released and the tank depressurizes. When tank pressure reaches its lower limit, the air compressor turns on again and re-pressurizes the tank.
Types of Compressors
Air compressors in sizes from 1/4 to 30 horsepower include both reciprocating and rotary compressors, which compress air in different ways. Major types of reciprocating compressors include reciprocating single acting, reciprocating double acting, diaphragm, and reciprocating rocking piston type. Major types of rotary air compressors include rotary sliding vane, rotary helical screw and rotary scroll air compressors.
RECIPROCATING SINGLE ACTING COMPRESSORS
Reciprocating single acting compressors are generally of one-stage or two-stage design. Compressors can be of a lubricated, non-lubricated or oil-less design. In the single-stage compressor, air is drawn in from the atmosphere and compressed to final pressure in a single stroke. The single-stage reciprocating compressor is illustrated in Figure 1. Single-stage compressors are generally used for pressures of 70 psi (pounds per square inch) to 135 psi.
ROCKING PISTON TYPE
Rocking piston compressors are variations of reciprocating piston type compressors. This type of compressor develops pressure through a reciprocating action of a one-piece connecting rod and piston. The piston head rocks as it reciprocates.
These compressors utilize non-metallic, low friction rings and do not require lubrication. The rocking piston type compressors are generally of smaller size and lower pressure capability
DIAPHRAGM TYPE
Diaphragm compressors are a variation of reciprocating compressors. The diaphragm compressor develops pressure through a reciprocating or oscillating action of a flexible disc actuated by an eccentric. Since a sliding seal is not required between moving parts, this design is not lubricated. Diaphragm compressors are often selected when no contamination is allowed in the output air line or atmosphere, such as hospital and laboratory applications. Diaphragm compressors are limited in output and pressure, and they are used most for light-duty applications.
ROTARY SLIDING VANE TYPE
The rotary sliding vane compressor consists of a vane-type rotor mounted eccentrically in housing. As the rotor turns, the vanes slide out against the housing. Air compression occurs when the volume of the spaces between the sliding vanes is reduced as the rotor turns in the eccentric cylinder. Single or multi-stage versions are available. This type of compressor may or may not be oil lubricated.
Oil-free rotary sliding vane compressors are restricted to low-pressure applications because of high operating temperatures and sealing difficulties. Much higher pressures can be obtained with oil lubricated versions. Some of the advantages of rotary sliding vane compressors are smooth and pulse-free air output, compact size, low noise levels, and low vibration levels.
Rotary helical screw compressors utilize two intermeshing helical rotors in a twin-bore case. In a single-stage design, the air inlet is usually located at the top of the cylinder near the drive shaft end. The discharge port is located at the bottom of the opposite end of the cylinder.
As the rotors enmesh at the air inlet end of the cylinder, air is drawn into the cavity between the main rotor lobes and the secondary rotor grooves.
As rotation continues, the rotor tips pass the edges of the inlet ports, trapping air in a cell formed by the rotor cavities and the cylinder wall. Compression begins as further rotation causes the main rotor lobes to roll into the secondary rotor grooves, reducing the volume and raising cell pressure. Oil is injected after cell closing to seal clearances and remove heat of compression. Compression continues until the rotor tips pass the discharge porting and release of the compressed air and oil mixture is obtained. Single or multi-stage versions are available. This type of compressor can be oil lubricated, Water lubricated or oil-free. Some advantages of the rotary helical screw compressors are smooth and pulse-free air output, compact size, high output volume, low vibrations, prolonged service intervals, and long life.
ROTARY SCROLL TYPE
Air compression within a scroll is accomplished by the interaction of a fixed and an orbiting helical element that progressively compresses inlet air. This process is continuously repeated, resulting in the delivery of pulsation-free compressed air. With fewer moving parts, reduced maintenance becomes an operating advantage. Scroll compressors can be of a lubricated or oil-free design.
CYLINDERS
Pneumatic equipment can be split up into two basic categories of cylinders and valves.
Cylinders are the ‘muscles’ of pneumatic systems as they are used to move, hold and lift objects. They can even be used to operate other pneumatic components. Cylinders are operated by compressed air and they covert the stored energy in the compressed air into linear motion.
There are two types of cylinder that we will be using: single-acting cylinders and double-acting cylinders.
Single-acting cylinder
A single-acting cylinder requires only one air supply. If we supply compressed air to a single-acting cylinder, the air pushes against the piston inside the cylinder and causes it to outstroke. When the piston has fully outstroke it is said to be positive.
If we stop the supply of air then the spring inside the cylinder causes the piston to in stroke to its starting position and the piston is said to be negative. As this happens, the air inside the cylinder is pushed back out.
The symbol for a single-acting cylinder is shown below.
Single-acting cylinder
Single-acting cylinders are easy to use and control but they do not produce very big forces. This means that we need to be careful of what we use them for.
CONSTRUCTION & WORKING PRINCIPLE
1. INTRODUCTION
Accidents are considered as non-avertable. Accidents occur due technical problems within the vehicle or due the mistakes of the drivers. Sometimes the drivers may become fatigue and they lose the control over the vehicle and sometimes the accidents occur due to drunken driver due to rash driving.
In all these cases the accidents occur because the brakes are not applied at right time.
The system designed will prevent such accidents. It keeps track of any vehicles in front. It will continuously keep track of the distance between the two vehicles.
When two come dangerously close the microprocessor in the system will activate the brakes and it will slow down the vehicle or bring it to a stop if needed.
2. NEED FOR THIS SYSTEM
2.1 ACCIDENTS:
Accidents are resulting in loss of invaluable lives, materials and money. So far the accident preventing systems are not very efficient and the loss of lives is continuing.
There are many systems like air bags, GPS, robot driven cars, tracked cars etc which can avert accidents to some extent.
2.2 CAUSES OF ACCIDENTS:
There are many causes of accidents. Some of them are
• ignoring traffic rules
• Drunken driving
• Dream driving
• Mechanical failures in the vehicle
• Mistakes of the drivers
In all these cases the basic reason cited is failure to apply the brakes at the right time. In all the above cases if the brakes are applied at the right time the accidents can be averted.
If a system is developed, which applies the brakes at the time of accidents automatically will avert accidents, which are caused by all the above reasons.
This project aims to overcome the mistake made by the drivers and at the time of accidents the system takes control of the vehicle and brings the vehicle to stop before colliding.
3. OUR VISION
Braking distance of a vehicle for a particular speed is the distance at which the vehicle comes to a halt from the current speed from the point of application of the brakes.
Here the speed of the vehicle is sensed and the corresponding braking distance is calculated using a microcontroller. The distance of the obstacle in front is also sensed.
4.1 Braking Distance
The braking distance is the main factor considered in this system. Braking distance for a particular speed is the distance between the point of application of the brakes.
The point at which the vehicle comes to a complete stop from the present speed. It is calculated using the following formula
Braking distance = V2 /2μg m
V - Velocity of the vehicle (m/s)
- Coefficient of friction of the road = 0.8
g - Acceleration due to gravity = 9.81 m/s2
In the formula the condition of the brakes and the road conditions are not considered for coefficient of friction.
CONCLUSION
The Intelligent Braking system, if implemented can avert lots of accidents and can save invaluable human lives and property. Implementation of such an advanced system can be made compulsory similar to wearing of seat belts so that accidents can be averted to some extent. Our Intelligent braking system provides a glimpse into the future of automotive safety, and how much more advanced these individual systems can be for avoiding accidents and protecting vehicle occupants when they are integrated into one system. The future of automotive safety is more than just developing new technology; it is shifting the approach to safety. INTELLIGENT BRAKING SYSTEM approach represents a significant shift from the traditional approach to safety, but it is fundamental to achieving the substantial benefits.