8 Sensors which are required for Autonomous Vehicles

self driving car

Autonomous vehicles or self-driving cars are being developed since the early 1950s. Over recent years we have seen significant development in this field. Companies like Google, Waymo, Uber, and Tesla are working extensively on this.

Today self-driving cars have become relatively advanced compared to their earlier counterparts. They can sense, plan, and act in a variety of situations where a normal human driver may fail.

So how cars can achieve autonomy? Obviously with the help of sensors, but what sensors?


Sensors can be divided into two categories: Exteroceptive Sensors used for sensing surroundings/environment and Proprioceptive Sensors used for measuring internal states.

Extroceptive Sensors

1) Camera

The most basic and important part of the environment perception is Camera. Autonomous vehicles rely on cameras placed on every side — front, rear, left and right — to stitch together a 360-degree view of their environment. Some have a wide field of view — as much as 120 degrees — and a shorter range. Others focus on a more narrow view to provide long-range visuals (Just another trade-off between resolution and field of view).  The data (images) collected from the camera is used for object detection and localization.



2) Stereo Camera 

stereo camera is a type of camera with two or more lenses with a separate image sensor or film frame for each lens. This allows the camera to simulate human binocular vision and therefore gives it the ability to capture three-dimensional images, a process known as stereo photography. 




3) LIDAR

LIDAR is a method for measuring distances by illuminating the target with laser light and measuring the reflection with a sensor. LIDAR produces laser beams to produce 3D scene geometry of the environment. Although LIDAR has high precision but may not give effective results in bad weather conditions. 


4) RADAR

RADAR helps in robust object detection and relative speed estimation. It overcomes the drawback caused by weather conditions in LIDAR due to its ability to work in poor visibility like fog and precipitation.




5) SONAR


SONARs are used for short-range all-weather operations. These are low-cost sensors that remain unaffected by light, precipitation, fog, etc. It is used in parking, lane changing, and detecting objects/vehicles near the ego vehicle (Autonomous Vehicle). 





All three sensor LIDAR, SONAR, AND RADAR work together to get precise data for the autonomous vehicle.




Proprioceptive


6) GNSS (Global Navigation Satellite Systems)


GNSS stands for Global Navigation Satellite System and is an umbrella term that encompasses all global satellite positioning systems. It enables autonomous vehicles to determine their position.




7) IMU (Inertial Measurement Unit)


It is an electronic device that measures and reports an angular rotation rate, acceleration, and heading. 


The position of the autonomous vehicle in a given plane is accurately calculated by the combination of GNSS and IMU.




8) Vehicle Odometry


It tracks wheel velocities and orientation to calculate the overall speed and orientation of the car. 






Self driving car



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