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Toshiba has made major advances in shrinking the laser projector unit of its LiDAR to one quarter the size of the previous version released in June 2021.
Using two of the new projector units, the LiDAR is just 206 cm3 in volume that can fit into the palm of the hand. Its range has been pushed out to 300 m, with an image resolution of 1200×84 pixels. It can be configured with flexible combinations of projector units to handle a variety of long-range and wide-angle detection applications.
The LiDAR will advance progress in Toshiba’s focus application areas, autonomous driving and infrastructure monitoring. It also opens the way to exploring partnerships in other areas, including robotics, drones and small security devices.
Toshiba initiated LiDAR research to advance autonomous driving and infrastructure resiliency. In addition to extending the range, with a wider viewing angle and better resolution, it had to make the LiDAR smaller. However, there has long been a trade-off in LiDAR range and size against the requirement of an eye-safe laser.
“To extend the range of a laser emitted by a single projector, you have to increase its intensity. If you do that, you also have to increase its emission width, to avoid a beam that focuses on a small spot and is strong enough to impair eyesight,” Akihide Sai, the senior research scientist at Toshiba’s Corporate Research & Development Center behind the new LiDAR, said. “The problem is, a wider emission requires a larger projector.”
Toshiba’s solution is a LiDAR that can use multiple small projector units as its laser beam source. They all emit an eye-safe beam in the same direction, which increases the effective range. This approach also keeps down the LiDAR’s overall size.
The advances that realized the new LiDAR started with shrinking the volume of the projector unit to 71 cm3. This was achieved with an innovative circuit design that reduced the motor control board by 60% against the size of the previous prototype, and by using know-how in 3D component mounting to reposition components and lenses.
The development team also drew on Toshiba’s proprietary motor control technology to come up with a triple control loop for the rotation speed, rotation angle and current of the polygonal mirrors in multiple projectors. This secures high accuracy synchronization, and the deviation angle of the mirrors is only 0.02 degrees or less.
In field tests, Toshiba confirmed that a LiDAR with two of the new projectors has a range of 300 m, 1.5 times further than its with a single projector. In very bright sunlight conditions, 100,000 lux, the two-projector LiDAR also showed much more detail in the scanned image than its predecessor.
The flexibility gained by combining multiple projectors, and fine-tuning control of the emitted laser, opens the way to customizing the LiDAR for long-range and wide-angle scanning. This will extend use to areas such as automatic guided vehicles, which must combine wide-angle views with long-range route monitoring.
Sai and his colleagues are building on current achievements for future advances.
“We are continuing research work that will advance our LiDAR technology, including solid-state LiDAR, toward boosting range and resolution, and making the LiDAR even smaller,” Sai said. “We aim to commercialize LiDAR for autonomous driving and infrastructure monitoring in fiscal year 2023, and look forward to exploring new applications in robots, drones, and security devices.”