In our past post “Google Driverless Car – under the Hood of the Car”, we mentioned about computer, display and map and navigation system of driverless car of Google. We are posting these articles to give you a holistic view of Google driverless car and how it works. Now in this post, we will be explaining about the obstacle detection system of driverless car of Google.
The obstacle/object detection unit of driverless car includes sonar devices, stereo cameras, a localization camera, a laser, and a radar detection unit. All of them have different fields of view and ranges. These sensors help robotic chauffeur (driverless car computer) to identify, track and predict the movements of pedestrians, bicycles, and other vehicles in the roadway. The robotic chauffeur makes driving strategies based on the information provided by obstacle detection unit.
Location and Use of Obstacle Detection Units in Driverless Car
According to Chris Urmson (tech lead of driverless car project), the laser range finder of the car is “heart of the system”. The laser is mounted on its top. It measures the distance between the vehicle and the object surfaces facing the vehicle by spinning on its axis and changing its pitch in other words by rotating. Velodyne 64-beam laser is mounted on roof of the self driving car.
The radar detection unit is used for adaptive cruise control systems. The radar detection is located on the front and back of the car as well as on either side of the front bumper. Sonar will be used also.
Varieties of cameras are mounted on the car those are separated from each other by a small distance. The parallax from the different images is used to compute the distance to various objects which are captured by 2 or more cameras.
Range of Obstacle Detection Units of Driverless Car:
The sonar has a horizontal field of view of approximately 60 degrees for a maximum distance of approximately 6 meters.
The stereo cameras have an overlapping region with a horizontal field of view of approximately 50 degrees, a vertical field of view of approximately 10 degrees, and a maximum distance of approximately 30 meters.
The localization camera has a horizontal field of view of approximately 75 degrees, a vertical field of view of approximately 90 degrees and a maximum distance of approximately 10 meters.
The laser has a horizontal field of view of approximately 360 degrees, a vertical field of view of approximately 30 degrees, and a maximum distance of 100 meters.
The radar has a horizontal field of view of 60 degrees for the near beam, 30 degrees for the far beam, and a maximum distance of 200 meters.
This is all about the various detection units, their location in the car and their ranges. The purpose behind using different units of different field of view and range is that they provide superb situational awareness and works in all type of weather. Like in fog, cameras may not give correct information but radar can provide efficiently.
The tech behind the car is very intriguing and we will be bringing more information about the car for you in upcoming posts.Be updated by following us on Google+ and liking our Facebook Page. You can follow our board at Pinterest.