Train Collision Avoidance Using Vibration Sensor & Micro-Controller

AbstractThere is an increasing with the number of accidents at railroad railings. Collisions with train are generallycatastrophic, in that the destructive forces of a train usually no match for any other type of vehicle. Train collisionsform a major catastrophe, as they cause severe damage to life and property. Train collisions occur frequently eludingall the latest technology. This paper deals about one of the efficient methods to avoid Train Collisions. This approachuses the Vibration sensor and a Proximity LASER Detector and the communication mechanism of PLC (Power LineCommunication) to communicate the Critical Details about the Train to the Control Room.

Problem DefinitionTrain Collisions are of different types depending upon the circumstance. The head to head collisions are nowadaysmostly avoided with the advancement in the technology. Anti Collision Devices have knowledge embedded intelligence.They take inputs from GPS satellite system for position updates and network among themselves for exchanging informationusing their data radio modems to take decisions for timely auto-application of brakes to prevent dangerous ' head to headcollisions' . so we have to focus on the other potential reasons for the dangerous mishap or catastrophe. The other mainreasons for the collisions of Train are: 1.Train Derailment in curves and bends,2.Running Train collisions with theStanding Train,3.Train Accidents in Slopes,4.Mis- signalling due to fog or Mist. Micro-controller and the embeddedtechnology is used in the coherence of the above operation with the sensors and relays and solenoid valves aselectromechanical switches. h Te Embedded technology has reached its peak so that the design can be so perfect withtime critical parameters.

Figure 1. Gap Detector

Details about the problemThe avoidance problem in this paper has been split into individual blocks and then joined together with timefactors for the complete solution. Bottom to top approach is used. The different blocks used to avoid the Collisionsby above mentioned reasons are:1.Gap Detector, 2.Vibration Sensor, 3.Proximity LASER Detector, 4.LED lighting or Fog penetratingLights, 5.FSK Modulator and FSK Demodulator (For Power Line Communication) .A Microcontroller for entireControl. The Microcontroller is interfaced with the input sensing devices such as vibration sensor, Gap Detector andproximity LASER Detector.

1. Gap Detector:Figure 1. Gap DetectorIn bends or curves, there should be gap between the rails of successive different paths. Even if there is a small gap, thetrain would get mislead and travel in a different path which leads to collisions in most of the cases. Already there aresensors to indicate the short circuiting of the gaps but practically even a small dust can short circuit the gap whichmakes the current system futile sometimes. Hence we use adjustable mechanical or elastic claw to find the gap andindicate the gap immediately to the Control Room. In the above figure, a rail road indicating a gap and next to it is aElectrostatic; capacitance-type Gap Detector : VE Series.

2. Vibration Sensor: It uses piezoelectric effect to detect the vibrations in the rails due to the arrival or departure oftrain and the direction of vibration indicate the arrival or departure. This could sense the train s position at roughly at800 to 900 m away. This input is fed to the microcontroller. This could help in avoiding accidents between trains inslopes because the arrival of one train found out using vibration sensor can be immediately sent to the Control Roomand the power supply can be switched off within 3 minutes so trains could be stopped without colliding each other.Vibration or shock sensors are commonly used in alarm systems to activate an alarm whenever the devices to whichthey are attached are touched, moved, or otherwise vibrated. Commercial vibration sensors use a piezoelectricceramic strain transducer attached to a metallic proof mass in order to respond to an externally imposed acceleration.Piezoelectric vibration sensors used for detecting vibration from various vibration sources are generally classified into

two large types, resonant type and nonresonant type.

Figure 2. An Example of Piezo-electric Vibration Sensor3. Proximity LASER Detector: Most of the collisions are of running train colliding with the Standing Train Types.A LASER detector can be used to detect the presence of any train before the running train. D A laser proximity sensorfor a train includes a laser diode having front and rear facets. The diode generates a main laser signal and directs afirst portion thereof out of the front facet as a source beam. Focusing means focuses the source beam on a target, andfocuses the return beam reflected from the target into the laser diode through the front facet. The laser diode receivesthe return light beam, provides it with a positive gain, mixes it with the main laser signal, and guides it out the rearfacet as a mixed beam. A detection focusing device focuses the mixed beam onto a PIN detector. The PIN detectorcoherently detects the mixed beam and provides an output signal having a perturbation where the target enters thefocal field of the focusing optics. A processor detects the output signal from the PIN detector and may activate abreaking mechanism in the train. The processor is also capable of determining the relative velocity between the trainand the target from measurement of the Doppler shifted signal or from the shape of the perturbation of the outputsignal from the PIN detector.

Figure 3. LASER Proximity Detector – setup

4.LED or Fog penetrating Lights are very useful during mist or fog seasons, as, near the signals, still manyemployees use explosives or other form of lights which involves the manual monitoring next to the signal 24*7. So,detecting the arrival of signal using Vibration Sensor, the LED lights can be made to switch off automatically in thesignals reducing the manual labour and monitoring and the driver from the train could get the signal easily even in fogtimes Any given snowy, foggy or rainy night can turn into a disaster because low visibility in these conditions canmaximize the potential of danger. Rough weather conditions call for precision driving, Using and installing fog lightscan help signals be seen better.5.FSK Demodulation and Modulation:Power line communication(PLC), also called power line carrier, mainscommunication, power line telecom(PLT), or power line networking (PLN) are terms describing several differentsystems for using electric power lines to carry information over the powerline. Data rates over a power linecommunication system vary widely. Low-frequency(about 100-200 KHz) carriers impressed on high-voltagetransmission lines may carry one or two analog voice circuits, or telemetry and control circuits with an equivalent datarate of a few hundred bits per second; however, these circuits may be many miles(kilometres) long.

Details about the set applied:

Figure 4. Layout section1.Vibration Detector - Train arrival Microcontroller Control Room Power off Stopping of TrainThis vibration detector helps to prevent head on collisions as well as train derailment and during mist conditions.2.Proximity LASER Detector Standing Train Detector MicroController Jamming the Brakes or Sending info toControl Room Power off Stopping of TrainThis operation helps to prevent the collision of running train over the Standing train3.Gap Detector Gaps in Bends or Curves Info about Trains path -1. Correct Path No problem 2. Wrong Path.Microcontroller Jamming the brakes or Sending info to Control Room Gap Correction or Power off Stopping ofTrain

Figure 5. Gap between the railsSmall gaps may lead to disastermisleading the train in different direction.4.Vibration Sensor Train Arrival Mist of Fog Times Microcontroller Automatic Switching of LED lights orFog penetrating Lights Microcontroller Control Room Communication5.Microcontroller FSK Modulator Main Transmitter PLCC Main Receiver FSK Demodulator PC inControl Room

All power line communications systems operate by impressing a modulated carrier signal on the wiring system.Different types of powerline communications use different frequency bands, depending on the signal transmissioncharacteristics of the power wiring used. Since the power wiring system was originally intended for transmissionof AC power, in conventional use, the power wire circuits have only a limited ability to carry higher frequencies. Thepropagation problem is a limiting factor for each type of power line communications. A new discovery called ELinethat allows a single power conductor on an overhead power line to operate as a waveguide to provide lowattenuation propagation of RF through microwave energy lines while providing information rate of multiple Gbps isan exception to this limitation.

Result and DiscussionThe sensors sense the input and sends to the microcontroller, where it responds and givescommand to the particular component with predefined algorithm. The time parameters are crucialwhich can be easily changed and modified using Micro-controllers. Thus, this device would work incoherence would help to reduce the train collisions.

SummaryACCIDENTS involving trains are gruesome. There s the magnitude of the loss involved, both of life andproperty, and the trauma it causes to the families of the passengers on board.In railway operations, it is the driver whois virtually driving blind in the block section because his vision does not cover the braking distance of a train, andonly at stations does he have signals to guide him. A simple misjudgement of the colour of a signal at a station canlead to a major mishap, notwithstanding the huge investment made in wiring the signals. Many a time, trains on thesame lines have collided head-on and caused hundreds of passengers to lose their lives. Thus this idea can improve thesafety of Train system. This idea can be a base and future modifications can be made for an optimised andsophisticated system.

Future DirectionsThe Anti Collision Device (ACD) is a self-acting microprocessor-based data communication devicedesigned and developed by Konkan Railway (KR). When installed on locomotives (along with an auto braking unit-ABU), guard vans, stations and level-crossing gates (both manned and unmanned), the network of ACD systemsprevents high-speed head on collisions in mid-sections, station areas and at level-crossing gates, thereby saving thelives of rail passengers and road users. This device can be integrated with the Anti Collision Device for bettersophistication and optimisation.

ReferencesCase Study made in North Coimbatore Railway Control Room.Collision Avoidance Systems www.collision-avoidance.orgVibration Sensors www.vibrametrics.com; www.ni.comRaksha Kavach Anti Collision Devices. www.konkanrailway.comCollision Avoidance Using GPS Device and Train Proximity Detector www.patentstorms.com.