AUTOMATIC HIGHWAY ANTI-COLLIDING SYSTEM

  

AUTOMATIC HIGHWAY

      ANTI-COLLIDING SYSTEM

moses dhilip kumar

                                           

                                   

SYNOPSIS:                 

·        Abstract

·        Introduction

·        Working principle

·        Construction details

Þ   Ultrasonic sensor

Þ   Relay

Þ   Non Inverting amplifier

Þ   DC motor

Þ   Solenoid

·        Working

·        Advantages

·        Conclusion

·        References

ABSTRACT:

                       We are living in an automobile society, and as far as this field is concerned the accidents are the main problems that have to be solved. In Chennai alone nearly 1900 fatal road accidents have taken place in 2005 which nearly claimed 1800 precious lives.

                                Driver’s assistance system plays a major role in cars since it minimizes the risk and consequences of accidents and increases the driving comfort level. Highway anti-colliding system is intended to provide drivers with brake assistance to avoid front end collision. On highways, if the principle other vehicle (POV) suddenly stops, then the host vehicle will collide it resulting in an accident. Due to less reaction time and loss of presence of mind, driver can’t stop the vehicle through brake.

              The aim of this paper is to stop the vehicle at such circumstances and this paper gives an outline of whole system and constructional features of each component and working principle. Adaptations of the system in the future automobiles have also been considered.

INTRODUCTION:

        

                              Most of the collisions take place between the rear of the principle other vehicle (POV) and the front of the host vehicle due to sudden stoppage of the POV and also this occurs when a vehicle is parked in the highways during night times which is not being recognized by the driver.  We are going to sense the stoppage of the POV (Principle other vehicle) using an ultrasonic sensor.  Any vehicle that reaches a critical distance (6-10m) towards the obstacle is necessary to be stopped and for this an actuating signal should be given to the relay and the solenoid. The sensor output voltage will actuate the brake shoes through solenoid and cuts the drive from the prime mover.

                                  This automotive collision avoidance has been developed in the centre for Automotive Research & Training, Department of Automobile engineering in MIT Campus, Anna University. The model on which the system is tested is made up of wooden chassis and a sheet metal body. A permanent magnet series motor is used to drive the vehicle. The current to the DC motor can be reversed to provide for a braking effort.

WORKING PRINCIPLE:

·        The principle of ultrasonic detection is based on measuring the time taken between transmission of an ultrasonic wave (pressure wave) and reception of its echo (return of transmitted wave). The distance range is 6-10 m.

·        The relay opens or closes its switch contacts in some prearranged and fixed combination. The contacts may be in the same circuit or a combination of circuit or in another circuit.

·        When a current is passed through the solenoid the slug is attracted towards the centre of the coil with a force determined by the current in the coil. The motion of the slug may be opposed by a spring to produce a displacement output, or the slug may simply free to move.

·        Torque is produced by interaction between the axial current carrying rotor conductors and the magnetic flux produced by the permanent magnets. The only way to control its speed is to vary the armature voltage with the help of an armature rheostat.

CONSTRUCTION DETAILS:

ULTRASONIC SENSORS:

Ultrasonic sensors have an acoustic transducer which is vibrating at ultrasonic frequencies. The pulses are emitted in a cone-shaped beam and aimed at a target object. Pulses reflected by the target to the sensor are detected as echoes.  The device measures the time delay between each emitted and echo pulse to accurately deter-mine the sensor-to-target distance.

    All materials sensing Ultrasonic Position Sensors solve the toughest sensing problems and detect targets made of virtually any material, regardless of color. They detect clear, transparent and shiny targets as easily as dark and opaque materials. This ability allows ultrasonic sensors to detect materials ranging from clear glass bottles to black rubber tires.  In a shrink wrapping operation, for instance, the sensor can accurately and repeatedly detect the wrapping material regard-less of how shiny or clear it may be. Ultrasonic sensors also work well in tough environments — fumes, dust, noisy.

Ultrasonic sensors are of the cylindrical type and they comprise of,

1. High voltage generator

2 .piezoelectric transducer (transmitter and receiver)

3 .signal processing stage

4. Output stage

Piezo  electric transducer

                                                              

Output stage

-20V

+20V

                

Signal processing stage

High voltage regulator

     

            Excited by the high voltage generator, the transducer (transmitter-receiver) generates a pulsed ultrasonic wave (200 to 500 kHz depending on the product) which travels through the ambient air at the speed of sound. When the wave strikes an object, it reflects (echo) and travels back towards the transducer. A micro controller analyses the signal received and measures the time interval between the transmitted signal and the echo. By comparison with the preset or learnt times, it determines and controls the output states.

     

The output stage controls a solid-state double switch (PNP and NPN transistor) corresponding to a NO contact (detection of object).

Input Voltage   : 10-30 V (DC).

Range               :  6-10 m.

Output Voltage: Analog, 0-10 V, 4-20 mA (PNP dual)

RELAY:

                     A relay is a device which functions as an electrically operated switch. In response to an electrical, known as control signal, the relay opens or closes its switch contacts in some prearranged and fixed combination. Dimension of the relay is about 95* 53*95 mm. The contacts may be in the same circuit or a combination of circuit or in another circuit. Supply voltage is about 15 volt.

         

NON INVERTING AMPLIFIER:

Vo = {1+ Rf/Ri}*Vi.

Rf and Ri is selected so as to give a gain of 1.4. We need the output voltage of 15 volt. The input voltage is 10 volts from the sensor. Rf and Ri is selected as 1.4 and 1 kilo ohms.

DC MOTOR:

                                 A permanent magnet dc (PMDC) motor is similar to an ordinary dc shunt motor except that its field is provided by permanent magnets instead of salient pole wound field structure. Ceramite ferrite magnets are used here. Low voltage PMDC motors produce less air noise and very little radio noise.

                     Torque is produced by interaction between the axial current carrying rotor conductors and the magnetic flux produced by the permanent magnets. The only way to control its speed is to vary the armature voltage with the help of an armature rheostat. Since magnets are permanent magnet, these are totally enclosed to prevent from magnetic junk.

SPECIFICATIONS OF PMDC MOTOR:

Torque	22 kg-m
Power	80 W
Speed	375 rpm
Voltage	24 V
Current	4.5 A

SOLENOID:

                            A solenoid consists of an electrical coil and a ferromagnetic slug which can move into or out of the coil. When a current is passed through the solenoid the slug is attracted towards the centre of the coil with a force determined by the current in the coil. The motion of the slug may be opposed by a spring to produce a displacement output, or the slug may simply free so that when the device is energized, it moves in one direction until it reaches an end to move.

               Most solenoids are linear devices, the electric current producing a linear displacement. They will give a continuous analog output or with a simple on/off input. The device is generally arranged when reenergized, a return spring forces it to the other end of its range of travel where it again reaches an end.

WORKING:

                  When the POV stops suddenly and if is within 6-10 m in front of our vehicle, the ultrasonic sensor will sense the reflected ultrasonic waves from the POV and generates an output voltage of 10 volts. This is given as input to a non inverting amplifier of R_f 1.5 kilo ohms and R_i 1 kilo ohms.  The output from the non inverting amplifier is 15 volts. This voltage is given as an input to a relay of 15 volts which is normally closed. The relay is normally closed with the DC motor circuit. Now the relay switch is opened thereby it cuts the DC motor drive. Due to inertial motion, the wheel tends to move in the forward direction. Using the same output voltage from the non inverting amplifier, the solenoid is actuated which presses the brake shoe against the wheel thereby stopping of the vehicle occur. Thus collision with the POV is avoided using our system. The following should also be incorporated with this system so as to avoid collision with our vehicle.

ADVANTAGES:

        

Ø Front End Collision is completely eliminated.

Ø The components used are easily available and construction is very simple; hence it a low cost technology.

Ø Practical implementation of the system is easy and necessary modifications are carried out for effective performance.

Ø Highly preferable at night hours during which most drivers feel fatigue.

LIMITATIONS:

                               While overtaking the forward vehicles, a certain distance should be maintained between the vehicles otherwise it leads to unnecessary braking of the vehicle. But this problem can be overcome by using a microcontroller in the system which analyses the signal and then only actuate the system.

CONCLUSION:

                               National Highway Traffic Safety Administration (NHTSA) estimates that most of the accidents involving forward end collision are due to the driver’s inattention or by vehicles following too closely and also it suggests a relatively simple technology needed for detection and prevention. Most of the accidents are forward collided. Thus by sensing the sudden stoppage of POV within the certain range in front of our vehicle, our brake system is actuated so as to avoid collision. The system can be further developed by using microcontrollers to analyze the signal. Thus this system is a safety system used in highways so as to avoid tail to head collision.

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MAGENN AIR ROTOR SYSTEM (M.A.R.S.)

MAGENN  AIR ROTOR SYSTEM (M.A.R.S.)

ABSTRACT

 Magenn Power Air Rotor System (M.A.R.S.), helium filled wind generator that rotates around a horizontal axis and sends electricity down a tether that can be used immediately, stored in a battery or routed to the power grid. The Magenn Power Air Rotor System (MARS) is a patented high altitude lighter-than-air tethered device that rotates about a horizontal axis in response to wind, efficiently generating clean renewable electrical energy at a lower cost than all competing systems. Airborne wind - turbines that fly in the sky and harvest energy from atmospheric wind has the potential, say proponents, of reducing the cost of wind power. In April of 2008, Magenn Power made history by having the world's first rotating airship. This paper presents an analysis of M.A.R.S and its developments. The physical behavior of machine is presented through its components. This system is a highly advanced one that is been not yet implemented till 2010.Now Canadian company is taking orders to distribute in 2011 in all the leading markets. This paper also presents a detail view of working and advantages.

                                

I.INRODUCTION

Wind is the fastest growing energy source in the world and one of the lowest priced renewable energy technologies today, at a cost of 4-6cents per killo watt hour."There is enough energy in high altitude winds to power civilization 100 times over; and sooner or later we're going to learn to tap into the power of winds and use it to run civilization."  Magenn Power's high altitude wind turbine called MARS, is a Wind Power solution with distinct advantages over existing Conventional Wind Turbines and Diesel Generating Systems including: global deployment, lower costs, better performance and environmental advantages operational 

.The wind is a completely renewable source that will last forever.  The life cycle for the energy gained from wind turbines is simply as long as the physical parts last. The generation of electricity from wind power takes place in several steps. It requires a rotor, usually consisting of 2-3 blades, mounted atop a tower; wiring; and "balance of power" components such as converters, inverters and batteries Wind turbines at ground level produce at a rate of 20-25%, but when placed at altitudes from 600-1000 feet, energy output can double. The Magenn Air Rotor System or MARS is a stationary blimp kept afloat with helium and tethered into place on an electrical grid. Centrifugal blades on the MARS can generate up to several megawatts of clean, renewable energy at a price well below our current grounded wind turbines. An airborne wind turbine is a design concept for a wind turbine that is supported in the air without a tower. Airborne wind turbines may operate in low or high altitudes; they are part of a wider class of Airborne Wind Energy systems (AWE) addressed by high altitude wind power. When the generator is on the ground, then the tethered aircraft need not carry the generator mass or have a conductive tether. When the generator is aloft, then a conductive tether would be used to transmit energy to the ground or used aloft or beamed to receivers using microwave or laser. Airborne turbine systems would have the advantage of tapping an almost constant wind, without requirements for slip rings or yaw mechanism, and without the expense of tower construction. As of 2010, no commercial airborne wind turbines are in regular operation.

 II.MAIN COMPONENTS OF M.A.R.S

A. Tether

A tether is a cord or fixture that anchors something movable to a reference point which may be fixed or moving. Energy generated by a high-altitude system may be used aloft or sent to the ground surface by conducting cables, mechanical force through a tether, rotation of endless line loop, movement of changed chemicals, flow of high pressure gases, flow of low-pressure gases, or laser or microwave power beams. A tether is a long cable usually made of thin strands of high-strength fibers or conducting wires. The tether can provide a mechanical connection between two space objects that enables the transfer of energy and momentum from one object to the other. The electrical current that is generated travels down the tethering lines to a transformer at the ground station, then is redirected to the power grid.

B. Helium balloon

A Helium balloon is a balloon that stays aloft due to being filled with a gas less dense than air or lighter than air. Today, balloons include large blimps and small rubber party balloons. Helium balloons work by the same law of buoyancy. As long as the helium plus the balloon is lighter than the air it displaces, the balloon will float in the air. Helium sustains the Magenn Air Rotor System, which ascends to an altitude as selected by the operator for the best winds

C. Helium

Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions.

D. Blade

The blades are relatively thin because this means they have a greater surface area to volume ratio and so are affected more by the wind.  For a simple demonstration, think of the difference between fanning yourself with a flat piece of paper and a rolled up piece of paper.  The flat piece causes a far greater movement of air and the same goes in reverse.  Air movement is going to affect the flat piece much more than the roll, although the weight is the same. The blades are also curved to increase their efficiency. 

As the blades move they cause a shaft in the body of the wind turbine to start turning.  This leads into a gearbox.  Gears transmit rotational energy in a similar manner to the cogs in an old fashioned clock.  The gears in the gearbox of a wind turbine end up spinning far faster than the blades were. Wind turbine blades turn at a speed of 10-50 revolutions per minute, and are equipped with regulators that shut the system down during hazardous weather to avoid having them spin out of control.

Blade Specifications: Obviously, this is the one variable that engineers can control. Longer, slimmer and lighter turbine blades can increase energy production. In his detailed May 5, 2010 article, Wind power Engineering Editor Paul Dvorak stresses the importance of turbine blades being as light as possible, yet durable enough to withstand high winds without breaking. Current blades range from 130-300 feet (40-90 meters), but future prototypes may be as big as 435 feet (145 meters).

E. Turbine

 There are two types of turbines. One is the vertical-axis type. It works like an egg beater. It works for small power uses: pumping water and grinding grain. This turbine cannot produce enough energy for electrical purposes. The second turbine is a horizontal axis, which has the capabilities of converting wind into electricity. This is the style used today on wind farms.

Turbines will generally last for around 120,000 hours, or about 20-25 years. Since they have moving parts, they require maintenance and repair, at a cost of about 1 cent per killo watt hour produced, or 1-2% annually of the original cost of the turbine.

The Honeywell turbine would measure 57 feet across and carry two one-megawatt turbines. In 34 MPH winds at 5,000 feet, the device would travel at 172 miles per hour and generate a megawatt of energy. The generator sits in the back of the device to add stability. This is done by the massive rotor blades, which form the visible part of a wind turbine. 

F. Generator

The wind turbine generator converts mechanical energy to electrical energy.

Wind turbine generators are a bit unusual, compared to other generating units you ordinarily find attached to the electrical grid. One reason is that the generator has to work with a power source (the wind turbine rotor) which supplies very fluctuating mechanical power (torque). A generator situated 500-1000 feet above ground level would enjoy much more consistent strong wind - which is why the Magenn MARS system makes so much sense. It's a helium-filled rotating airship that spins in the wind on the end of a variable-length tether that also acts as a power transmitter, and it's expected to operate at more like 50% of its rated capacity.

On large wind turbines (above 100-150 kW) the voltage (tension) generated by the turbine is usually 690 V three-phase alternating current (AC). The current is subsequently sent through a transformer next to the wind turbine (or inside the tower) to raise the voltage to somewhere between 10,000 and 30,000 volts, depending on the standard in the local electrical grid. Large manufacturers will supply both 50 Hz wind turbine models (for the electrical grids in most of the world) and 60 Hz models (for the electrical grid in America).

COOLING:

Generators need cooling while they work. On most turbines this is accomplished by encapsulating the generator in a duct, using a large fan for air cooling, but a few manufacturers use water cooled generators. Water cooled generators may be built more compactly, which also gives some electrical efficiency advantages, but they require a radiator in the nacelle to get rid of the heat from the liquid cooling system

 III.Working
Wind spins a turbine's blades, which, in turn, cause an attached generator to also spin.  The wind blows through blades (made of fiberglass-reinforced polyester – this makes the blades lightweight and yet strong enough to withstand the force of the wind).The blades change the wind's energy into a rotational shaft energy (think of a standard fan).The shaft connects to a drive train with a gear box that uses the rotation of the blades to Spin the magnets in the generator to produce mechanical energy This mechanical energy  is imparted to the shaft in the hub of the turbine and causes a great amount of torque to develop on the shaft. At the other end of the shaft, a gearbox transfers the energy to a secondary shaft. The step up gearing causes higher revolutions per minute (rpm) in the secondary shaft and consequently lower torque. A generator or alternator is mounted on the secondary shaft, and converts the mechanical energy originally imparted by the wind to the turbine. A protective cover, “nacelle”, houses the shaft, drive train and generator.

The generator then converts that moving energy of the wind into electricity using electromagnetic induction, which involves using the opposite charges of a magnet to create an electric current.  The generators are at each end of the rotor with a direct output power connection to the twin cables.  Outboard of the generators at each end of the rotor are wind vane stabilizers in the form of conical wheels. The deviation in the trajectory of a spinning projectile caused by the Magnus force. The deviation is toward the direction of the spin and results from pressure differentials in the spinning projectile. The Magnus effect is greatest when the axis of spin is perpendicular to the direction of relative fluid velocity The Magnus effect, associated with the rotor rotation, also provides additional lift, which stabilises the rotor position causing it to pull up overhead, rather than drift downwind on its tether.

Wind causes the blimp to rotate: That movement gets converted into electrical energy and is then transferred down the tether.

Instead of the large pinwheel blades that are typical of wind turbines though, the blades of the M.A.R.S turbine are actually part of the three-dimensional blimp itself. The blades catch the wind, causing the entire blimp to spin around. After the generator converts that movement into electricity, it's transferred down the turbine's long tether. ­Whereas most regular turbines capture winds at­ altitudes of 200 to 300 feet (61 to 91 meters), the MARS turbine can reach winds from 600 to 1,000 feet (183 to 305 meters) above ground level. Winds at these higher levels are significantly faster than low-level winds because they don't encounter as much resistance from objects on the ground like trees and buildings. Research shows that with each doubling of elevation, there is a 12 percent increase in wind speed with each doubling of wind speed there is an eightfold increase in wind power

The wind pushes the rotor blades, converting kinetic energy to rotary motion. This spins a low-speed shaft, which turns a gear at the lower end. The gear in turn drives a smaller gear on a high-speed shaft that runs through generator housing.

A magnetic rotor on the high-speed shaft spins inside loops of copper wire that are wound around an iron core. This creates "electromagnetic induction" through the coils and generates an electric current. The current must be regulated for the strength of current desired (110 w in the US for household AC current). It is then fed into a grid or routed into a battery bank for later use.

IV.INSIDE M.A.R.S

Magenn Power designed its turbine not only for easy deployment, but also for easy maintenance. Obviously, a blimp like object floating at 1,000 feet (305 meters) could receive quite a beating from the elements, but the company estimates the MARS should last at least 15 years before requiring maintenance. To achieve this longevity, the inflatable part of the turbine is made from an extremely durable fabric used by most current airships. The woven outer part is actually made from the same material used in bulletproof vests and is lined with a coating that protects it from UV rays and abrasion. The inner portion is coated with Mylar (the silver part you see in helium balloons) to prevent the helium gas from escaping. Since the MARS is located at such high altitudes, it was also designed to be able to withstand strong winds. While conventional turbines will shut down at wind speeds in excess of 45 mph, the MARS can function at speeds greater than 63 mph. At the other end of the spectrum, the MARS turbine can also convert wind energy into electricity at wind speeds as low as 7 mph

Part of what enables the MARS to stay vertical at high wind speeds is due to something called the Magnus effect. This refers to the lift created when a curved object spins while moving in a fluid medium like air. When the object spins, an area of high pressure forms beneath it and causes it to rise. Golf balls, when hit a certain way, and curveball pitches in baseball, have a back spin that causes them to lift in flight -- this is the Magnus effect. Since the effect increases as wind speed increases, the MARS is able to use it in combination with the lift from the helium to maintain a near vertical position and not lean in high winds.

The wide range of speeds at which it can operate means that the MARS can deliver output much closer to its rated capacity than standard designs can. This is because although wind energy can theoretically generate significant amounts of electricity, most generators only produce a fraction of that because of inconsistent winds.

V.ADVANTAGES

The Advantages of MARS over Conventional Wind Turbines are:

Low cost electricity - under 20 cents per kWh versus 50 cents to 99 cents per kWh for diesel

Bird and bat friendly Lower noise

Wide range of wind speeds - 3 meters/second to more than 28 meters/second Higher operating altitudes - from 500 feet to 1,000 feet above ground level are possible without expensive towers or cranes

Fewer limits on placement location - coast line placement is not necessary. Ability to install closer to the power grid Mobile Ideal for off grid applications or where power is not reliable.

                                                       VI.CONCLUSION

M.A.R.S is  first tested on April 2008 successfully by Fred Ferguson .Thus MARS is the most efficient, cost-effective, eco-friendly, mobile, low maintenance way of generate electrical energy out of wind energy. Due to inadequate supply of power production many private sector have turned their vision towards thermal power plant. In 2015 there could be around 9 thermal power plant in Tuticorin to meet the energy need. Due to the introduction of MARS many private sectors have turned their attention towards it because of its advantages over other systems.

 It would be ideal for the country like India which having vast verities in geographical landmarks to implement such power stations as it could be installed where it could be. It is the best solution for the power-crises faced by whole world.