Research and industry are gradually getting closer to the dream of autonomous driving. Lidar systems are an elementary part of a car that is less and less dependent on active control on the part of the driver. In this blog, we have summarized which functions such systems are already taking on today and what role sensors play in particular.
Lidar (light detection and ranging) technology forms the basis of effective driver assistance systems such as adaptive cruise control, a collision warning system, lane change assistant and blind spot alert. Even though lidar is related to radar, it uses laser beams instead of radio waves in order to measure speeds and distances. With their extremely high angle and distance resolution, lidar systems supplant conventional radar and camera systems. By means of software, a very precise model of the area around a vehicle can be created. Not only does this detect road users such as other four-wheeled or two-wheeled vehicles and pedestrians, it also provides information about road markings, signs and other traffic facilities such as barriers or traffic lights.
Requirements to Be Met by Lidar Systems
What automotive and mobility requirements must such a measurement system meet? And, in particular, what challenges do the sensors used need to overcome?
- Monitoring the surrounding area: Vehicles that drive at high speeds in particular need an extremely wide "visual field," a predictive system that is as effective as possible and an extremely quick and reliable detection system.
- Resistance: The sensors used must be able to withstand various environmental influences and all weather conditions as well as wind speeds.
- Conformity: The electronic system must naturally comply with the usual industry requirements, and the sensors used must fit into the overall design of the sensor system used.
- Cost efficiency: A lot is possible, but not everything can be achieved within a financially viable framework. People who develop lidar systems also need to keep an eye on the costs and look for a solution that is 100% reliable while also being cost-effective.
What system meets the requirements of maximum safety and resilience? A long-range lidar system that detects objects at distances of up to 300 meters is the best laser to choose for vehicles that operate at high speeds. Various sensor solutions are available for use in the automotive sector.
LIDAR-scanner in action
Essential: Reliable Sensors
At the heart of any lidar system are its sensors. Every sensor technology has its own advantages and disadvantages. Here is a compact overview:
Silicon PIN photodiodes
These silicon-based detectors are made up of three eponymous semiconductor types: P-type, Intrinsic, N-type.
+ Very wide dynamic scope, relatively inexpensive
- Lag behind the good signal-noise performance that modern lidar systems require; not overly quick
Silicon photomultipliers (SiPM) and single-photon avalanche diodes (SPAD)
Originally developed for small-scale applications in a scientific and medical setting, these detectors are slowly making inroads into lidar.
- Danger of oversteering; unfavorable signal-to-noise ratio; very temperature-sensitive
+ Good amplifier characteristics; very quick; chip-compatible with CMOS
Indium gallium arsenide photodiodes (InGaAs)
A technology that manages without the usual silicon. InGaAs are still relatively new in the world of lidar; they are commonly used in small fiber-optic networks in the telecommunications industry.
+ Measuring long distances; wide spectral range
- Temperature-sensitive; complex and expensive to manufacture
Avalanche photodiodes (APD)
Brought to maturity using industrial and military technology, APDs are now a standard feature of most vehicles involved in autonomous driving.
+ High sensitivity; optimum signal-to-noise ratio; quick; inexpensive
- Not compatible with CMOS technology
How to Choose the Best Sensor
No driver assistance system can survive without lidar. Sensors in turn play the hidden main role in this technology, and autonomous driving would be inconceivable without them. Without the use of laser beams, it would not be possible to measure distances and speeds of objects safely.
How can you find the best sensor system for your field of application for lidar? And what about a manufacturer's experience and qualifications in the automotive sector? What support services can you build on? Can the detectors be customized to meet your needs and requirements?
Download the free "Making sense of sensors" white paper. This lists the most important criteria for you in the selection of sensors as well as their manufacturers. It will help you to find the best partner to offer you the best possible support with your autonomous driving project.