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How exactly does lidar work?

Technology

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09/09/2019
 

Driver assistance and safety systems help prevent accidents. At VisionZeroWorld we explain how ABS, ESC and other safety-related technologies work. This time it’s the turn of lidar.


On a stretch of the A5 Autobahn skirting Frankfurt, Germany’s banking capital, Continental is testing a new technology with the potential to revolutionize the future of driving. The test begins conventionally enough, with the vehicle being driven manually by the driver. Then a computer voice invites the driver to take his hands off the wheel and his foot off the gas pedal, handing over control to a new driver assistance system called Cruising Chauffeur. Cruising Chauffeur marks the next phase in autonomous driving. This innovative technology supports highly automated highway cruising based on perfect interaction between newly developed sensor systems and those that have already proven their worth in other assistance programs. Together, cameras, sensors and radar systems provide 360-degree real-time all-round monitoring of the vehicle environment. A further technology which also plays a leading role here, and which is key to making autonomous driving possible, is lidar.

The detailed environment models generated by state-of-the-art driver assistance systems with the help of innovative lidar technology will also play a key role in implementing future autonomous driving functions. Photo: Continental

 

Lidar (Light Detection and Ranging) is similar to conventional radar sensing except that it uses laser beams rather than radio waves to gather data. This cutting-edge technology is playing a key part in autonomous vehicle development. Because before the driver can be replaced by an on-board computer, the vehicle must first be capable of detecting its environment and also, simultaneously, of predicting and interpreting the behavior of other road users and translating this information into the appropriate maneuvers. Bearing in mind that no single sensing principle in isolation can meet all the requirements posed by modern driver assistance systems under all conceivable environmental and driving conditions, Continental uses various different types of sensor in combination. These include cameras, radar and now also lidar, where the company has developed its own 3D flash lidar system with very high resolution. This innovative Continental Hi-Res 3D Flash LIDAR technology is an important addition to the current environment sensor portfolio for highly and fully automated driving systems. Major advantages of lidar sensing technology include its ability to support both real-time image analysis and environment recognition functions. Lidar technology provides a significantly more comprehensive and detailed all-round picture of the vehicle environment, both during the day and at night, and works reliably even in adverse weather conditions.

A small component with a big impact: Continental’s “Hi-Res 3D Flash Lidar”. Photo: Continental

 

Lidar sensors are already being used in assistance systems such as Autonomous Emergency Braking. In order to scan the vehicle environment with pinpoint accuracy, the sensors emit laser beams which are reflected back by objects in their path. The reflected waves return to the source point, where a detector uses the time lapse between signal emission and reception to calculate the distance from the object. This allows the range and position of individual measurement points to be determined with a high degree of precision. The resulting information can then be classified by clustering the individual measurement points into objects. The whole process takes place in just fractions of a second, in other words virtually in real time. Lidar scanning is performed approximately one thousand times per second. Each time, the collected data is used to produce an all-round 3D map of the vehicle’s environment. As a result, the lidar sensors become aware of traffic situations – and identify the required responses – before these situations are even detected by the driver. During the one second that is the typical reaction time of a human driver, the lidar system will already have scanned the environment 1,000 times. Based on the accumulated data, movement profiles are produced for individual road users. The vehicle can then establish in good time whether it needs to take pre-emptive action, for example to avert a critical situation.

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