New projection technology could make autonomous cars safer for pedestrians and cyclists

Imagine a situation where a pedestrian is unsure if an approaching autonomous car will yield or not. In this scenario, a bright projection appears in front of the vehicle, indicating that it has detected the pedestrian and is waiting for them to cross. This is just one example of how future cars and pedestrians might communicate with each other on the streets.

Researchers involved in the MaMeK project, such as Norbert Danz and his team at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena, are exploring different scenarios for human-machine communication. The project focuses on projection systems for this purpose and involves partners like Audi AG. They are working on two technological approaches: displays directly on the car and holographic projections on the ground around the vehicle. Fraunhofer IOF is responsible for the technology behind the latter.

Currently, many cars have LED-based symbol projection systems that project images onto the ground when the driver exits the vehicle. However, these projections are not bright enough for daylight conditions, and the images are static, making them unsuitable for enabling autonomous cars to communicate effectively with their environment. To address this challenge, the researchers aimed to develop an ultra-bright projection system that would be visible even in sunlight and capable of displaying dynamic information. It also needed to cover a large area around the car using only a few projectors.

By implementing advanced projection technology, future autonomous cars could use dynamic and highly visible projections to communicate their intentions to pedestrians, cyclists, and other road users. These projections would provide a clear signal of the vehicle’s awareness of their presence and its willingness to yield or wait for them to cross safely. This innovative approach has the potential to enhance safety and foster better interaction between autonomous vehicles and pedestrians in the future.

Measuring 7 x 7 x 5 cm, the projector can be integrated into any car sill and cover a projection area of 100 x 30 cm. Credit: Fraunhofer-Gesellschaft

Crystal-clear projections in sunlight and over wide angles

The researchers at Fraunhofer IOF are utilizing cutting-edge laser technology to implement their dynamic micro-projector. Their system involves four laser diodes that illuminate a spatial light modulator (SLM), which distributes the light to form a specific image on the road. To achieve the desired brightness and maximize the projection area, the system generates four sub-images that are merged into one. Due to the projector’s close proximity to the ground and wide projection angle, creating a single large image is challenging. Instead, the image is divided among multiple laser diodes, and micro-optic telescopes are used to expand each individual image. The direction of projection is determined by an array of microprisms, enabling a projection area of 100 x 30 centimeters at a distance of less than 50 centimeters.

Remarkably, the system developed by Fraunhofer IOF has compact dimensions of only 7 x 7 x 5 centimeters, allowing for easy integration into any car sill. By installing multiple projectors, it becomes possible to display pictograms around the entire vehicle, and the modular architecture also enables the depiction of dynamic elements. However, the system’s standout feature is its brightness level, reaching approximately 10,000 lux (depending on the image). This exceptional brightness ensures that road projections remain visible to cyclists and pedestrians even on sunny days. Achieving this brightness involves various components, including the SLM image generator provided by Holoeye Photonics, a project partner based in Berlin. Docter Optics SE, a medium-sized enterprise from Thuringia, Germany, is also involved in the construction of the projectors.

The overall system developed within the MaMeK project is currently being integrated into a demonstration vehicle and connected with suitable sensors from a highly semi-autonomous vehicle. At the LASER World of PHOTONICS trade fair, the Fraunhofer researchers will exhibit a laboratory demonstration model of the micro-projector for the first time.

Source: Fraunhofer-Gesellschaft

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