Major technology companies such as Google, Apple, Ford, Audi, Tesla and spending a lot of money in the development of self driving cars. Self driving cars will also reduce the transportation cost because humans are not required to drive autonomous vehicles.
According to data, 90% of road accidents are caused by human error. Autonomous vehicles will also reduce road accidents. But this does not mean autonomous vehicles will reduce accidents to zero. In recent times we see a lot of news about self driving cars causing accidents. Lot of testing is going on to improve autonomous vehicles. In this article we will discuss what are self driving cars and how they work.
What are Self Driving Cars?
Self Driving cars does not require human driver to reach from one location to another. They can recognize traffic light, road signs, detect obstacles, predict the behavior of other driver and act accordingly.
Lyft and Uber are developing Self driving cars that can pick passengers and drop them at their destination. General motor and tesla are also testing self driving trucks.
Self Driving Car (Autonomous Vehicle) Levels
According to the extent of automation, Society of Automotive Engineers (SAE) has classified Autonomous vehicles in six levels.
Level-0 : Most of the cars we have on the road are Level-0 autonomous vehicles. These vehicles have no automation. Vehicles equipped with proximity rear sensor, rear camera and cruise control comes in level-0 category only.
Level-1 : If autonomous vehicle can control by itself based on environmental sensor data. These vehicles involves features such as lane assistant system and radar based cruise control.
Level-2 : These autonomous vehicles have some level of automation. Level-1 autonomous vehicle can steer the car and change acceleration. These cars include feature such as Changing lane during cruise control and self parking etc. But in this Driver need to be always attentive. E.g. Mersdize Benz Intelligent drive forward thinking system.
Level-3 : These autonomous vehicles are capable to self drive on certain roads. But in tricky situations human has to instantly take over. Therefore they don’t offer much advantage to the driver.
Level-4 : These autonomous vehicle are smart enough to handle tricky situations. They can operate without any driver inside but limited to some locations only. Whereas on other locations they utilize human driver as fail safe. Google Waymo is Level 4 Autonomous vehicle. Whereas Ford is going to launch Level 4 autonomous vehicles by 2021.
Level-5 : These autonomous vehicles are driverless vehicles in true sense. They can completely control by itself. Any intervention from the driver is not required.
Self Driving Cars Benefits
- We are terrible drivers. According to national highway safety administration 90% of road accidents are caused by human error. This will reduce with self driving cars.
- Reduced Road Congestion.
- Reduced Pollution
- Self driving cars will reduce the transportation cost as no human will be involved.
- More convenience for children and old people.
How Self Driving Cars Work?
Self Driving cars can recognize traffic lights, road signs, detect obstacles, predict the behavior of other drivers and control the vehicle accordingly. They utilizes the following five major components to take passengers from one location to another:
- Array of Sensors (Autonomous Vehicle Vision)
- Vehicle Positioning
- Path Planning
- Vehicle Control
Camera : Computer Vision
Like the way humans use eyes to see the outside world and take decisions accordingly. Self driving cars utilizes computer vision to see the road. Camera along with other array of sensors are used to create self driving car outer environment.
Unlikely to human eyes which have only front vision. Autonomous vehicles have an array of camera all around them. Camera images are processed by deep learning algorithms. It helps in:
- Object detection and classification
- Detecting other vehicles
- Obstacle Detection
- Understanding Traffic Lights
- Recognize lanes and sign board
- Other Driver behavior Estimation
LIDAR : Light Detection and Ranging
LIDAR is a laser based radar system. It works similar to radar but instead of radio waves it utilizes light waves that are reflected by objects. In this way point cloud for outside environment is created. It allows self driving car to detect far objects.
Limitation of LIDAR is it can not recognize road signs or can not differentiate between a stone or polythene bag. Some companies such as Tesla are making self driving cars without LIDAR. Because they are very expensive sensors. LIDAR for self driving car cost approximately $7000 to $10,000.
RADAR is used in self driving cars to find how far the object is and how fast it is moving. But is is unable to recognize objects. For example it will consider a polythene and stone as a same object.
Radar is also not able to detect smaller objects on the road. For example radar can detect car but not bicycle.
They are used to detect objects at relatively smaller distance. For example Ultrasonic sensors are used in self driving car for parking.
2. Vehicle Localization and Mapping
After understanding the world around the self driving car. Next step is to determine vehicle position. GPS technology is used to determine autonomous vehicle position. But GPS has following problems:
- GPS have an accuracy in the range of 5 to 10 meters. Which is very high for an autonomous vehicle.
- GPS do not work in tunnels
Therefore GPS, Wheel odometry, digital maps and information from camera is used to predict vehicle position within a few centimeters. Digital maps contains the information about landmarks, road signs etc.
Vehicle speed, its wheel diameter is also used to predict vehicle position more accurately.
3. Trajectory and Path Planning
After we have autonomous vehicle accurate position in the outside world. Next step is planning vehicle optimized path from one position to another.
This process involves predicting the behavior of other vehicles and plan accordingly. In future when there will lot of self driving vehicles on the road. These self driving cars will communicate with each other and will take decisions accordingly.
4. Vehicle Control
To control autonomous vehicle we need to turn the steering wheel, control vehicle acceleration and apply brakes. Self driving cars take these decisions based on outer environment.
PID (Proportional Integral and Derivative) Controls are used to control the vehicle.
To sum up, Self driving cars will bring the next revolution in transportation sector. It will help in reducing fatal road accidents and reduce congestion on the road.
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