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Collision Avoidance System (CAS)
Context:
There is a need for a Collision Avoidance System (CAS) due to increasing Vehicular traffic in modern life.
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What is a Collision Avoidance System (CAS)?
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Importance for land-based vehicles:
- Considering two cars, the Back Car’s system will monitor the speed of the Front Car, the distance between the two vehicles, and its own speed.
- If the gap between the cars is predicted to fall below a certain threshold within a specified time, the CAS may automatically engage the emergency brakes—such as those required in vehicles in the European Union—without the driver’s input.
- To accomplish this, the CAS must be integrated with the Back Car’s braking system, allowing it to override the driver’s commands.
- It will also need to connect to the vehicle’s speedometer and be equipped with sensing technologies, such as radar, lidar, or cameras with object recognition, to track the Front Car’s movements.
What is Kavach?
- It is the indigenous CAS developed for Indian Railways.
- Kavach consists of three primary components: computers, communications, and control.
- Computers: Kavach includes a computer onboard the train, as well as two additional computers for station masters.
- One of these, the master computer, gathers and processes information from signals and interlocking points, then sends its output to the locomotive computer.
- The locomotive is equipped with two radio-frequency identification (RFID) readers mounted underneath. These readers scan RFID cards installed at fixed intervals along the tracks. As the train passes over these cards, the readers retrieve the train’s location and track ID, sending this information to the onboard computer.
- The other, called the remote interface unit, also collects and processes data from various points across the railway network, eventually transmitting this data to the master computer. However, it does not communicate directly with the locomotive computer.
- Communication: The remote interface unit transmits data to the master computer via fiber-optic cables. The master computer then communicates with the locomotive computer using ultra-high frequency radio.
- Additionally, the onboard computer uses GSM-Railway to connect with the broader network management system (the software that powers the Kavach CAS), ensuring authenticated communication with nearby master and locomotive computers.
- Control: Similar to cars, the onboard computer is connected to various components of the locomotive, including its braking system and an alarm to alert the pilots. Pilots operate the locomotive using a custom interface—such as a digital screen—that displays information from the computer and accepts pilot inputs. The station master has a similar interface, with the capability to send SOS messages as needed.
Collision Avoidance Systems (CAS) in Ships and Aircraft:
- In aircraft, the Traffic Collision Avoidance System (TCAS) also operates with a computer-communication-control setup, similar to trains.
- A key component of TCAS is the transponder, a device that responds to a radio-frequency ping by sending back a signal. By interacting with the transponders of nearby aircraft, the host aircraft can build a 3D map of the surrounding air traffic. A critical feature of aircraft CAS is its alert system. Additionally, aircraft may be equipped with radar altimeters to measure the distance to the ground and systems that warn pilots of tall obstacles such as towers and antennas.
- In ships, CAS relies on a combination of visual sightings and radar to avoid collisions, supported by additional systems.
- Two key technologies are the Automatic Identification System (AIS) and Long Range Identification and Tracking (LRIT).
- The AIS involves base stations on land tracking and coordinating data received from transceivers onboard ships, which include information about the ship’s location, speed, and bearing. This data is then transmitted to other vessels.
- LRIT, or Long Range Identification and Tracking, requires ships on international voyages to report their location, local time, and onboard equipment every six hours to the authorities of the country whose flag the ship is flying.
- This information is shared with contracting governments and search-and-rescue operators through the International LRIT Data Exchange.
Satellites and Collision Avoidance Systems (CAS):
- One notable alternative to the transponder-based system for aircraft is the Automatic Dependent Surveillance-Broadcast (ADS-B) system.
- ADS-B actively shares information from each aircraft via satellites, allowing for a precise understanding of the relative location, bearing, and speed of nearby aircraft. Similarly, the Automatic Identification System (AIS) for ships can also be supported by satellites, leading to Satellite-AIS (S-AIS) systems. These systems are particularly useful for tracking ships that are too far from land-based AIS stations.
- The introduction of the U.S. Global Positioning System (GPS) revolutionised navigation and collision avoidance worldwide. Some countries have supplemented GPS with their own systems to meet specific national requirements.
- For instance, India plans to use its NavIC constellation of navigation satellites to assist road and railway traffic across the country.