In the future, laser systems will help self-driving cars to perceive their surroundings in real time. In combination with cameras or radar, this should ensure more security. However, these “lidar” systems are still too expensive and susceptible to the vibrations that naturally occur when driving. An Austrian research team has made progress here and reports about it in the specialist magazine “Journal of Optical Microsystems”.
“Lidar” hides the term “light detection and ranging”, i.e. scanning the environment and estimating distances using light. In order to be able to reliably drive autonomously, “redundant systems” are needed with which the strengths and weaknesses of individual other devices for perceiving the environment can be compensated for. Lidar systems emit laser pulses and detect the light reflected from objects. The distance to it can then be calculated from the propagation time of the light. With a corresponding amount of laser pulses, more or less the entire area can be scanned very quickly.
A team led by Georg Schitter from the Institute for Automation and Control Technology (ACIN) at the Vienna University of Technology and Leonhard Kormann from Infineon Technologies Austria in Graz is researching the potential of this technology for autonomous driving. Depending on the environmental conditions, current systems manage distances of between 50 and 100 meters. “Long-range lidar is one of the biggest unsolved problems at this point,” said Schitter in an interview with APA. The team is therefore trying to develop lidars with a range of around 200 meters. In this field, one is internationally among the leading research associations.
New control engineering methods from Vienna and Graz
The scientists rely on a structure in which the laser beam is distributed in all desired directions via a movable mirror. However, these MEMS systems (microelectromechanical systems) are susceptible to shocks. The researchers from Vienna and Graz recently presented new control technology methods “through which this oscillating MEMS mirror is stabilized,” explained Schitter. By controlling the mirror, the usual vibrations “of a few kilohertz” can be demonstrably compensated. If it is moved from the desired position by vibrations, this is registered and actively compensated. This type of interference suppression already works very well.
This brings the team closer to the goal of building lidar systems that are relatively inexpensive. The devices available to date are intended for use in vehicles, but at 8,000 to 10,000 euros for just one sensor they are still far too expensive. In the automotive sector in particular, the costs for components are often low in euros and cents. If you create a lidar sensor for less than 1,000 euros per piece, “it gets interesting,” says Schitter. In order to be able to cover the long and close range well, you need around four fist-sized sensors, which could be mounted next to the headlights.
It will be cheaper if such MEMS systems can be mass-produced. This is also the motivation of the semiconductor producer and project partner Infineon. “Lidar sensors in the close range are also very interesting for turning assistants in trucks” to avoid accidents with cyclists or pedestrians due to the blind spot, stressed Schitter. (apa)
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