Robosense M Series lidar sensors
Lidar manufacturer Robosense is one of several Chinese vendors that are now supplying these laser-based sensors for several production automotive programs including the Lucid Air and versions of the Kia EV9 sold in Korea. At CES 2024, it is introducing two new sensors including the longer-range M3 and the lower cost M2. Distance Sensor High Precision
Robosense’s current generation M1 and M1+ automotive sensors both utilize 905 nm lasers which are common among most early generation lidars, along with MEMS systems for two-dimensional steering of the beam. These sensors have a range of up to 200 m against a target with 10% light reflectivity. The new M2 is a lower cost evolution of the M1 design that claims to provide some improvement in performance, although exactly how much is unclear.
Within the lidar community, there are two main schools of thought on laser wavelengths. Starting with the original Velodyne lidar sensors that were used on the vehicles in the DARPA Grand Challenge or 2003-2007, most of the early sensors and many still being produced and developed today use laser emitters in the 905-940 nm wavelength range.
The emitters required for this have become relatively affordable and work well, but lasers in this range can cause retinal damage if it enters the eye. As a result the power levels of these lasers are limited to minimize that risk. That power limitation also tends to limit the detection range of these sensors. However, many of the leading vendors producing these kinds of sensors are now achieving detection ranges of 250-300 m which is considered adequate for detection of objects at highway speeds for light duty vehicles.
The other main lidar type uses 1550 nm lasers which pose no real threat to vision, but are considerably more expensive. However, because they are considered eye-safe, they can run at higher power and achieve longer detection ranges. Some 1550 nm lidars from companies like Luminar and Aeye have been demonstrated to reliably detect objects beyond 400 m distance and out to as much as 1,000 m. Companies like Volvo and Mercedes-Benz have chosen the Luminar sensor for future vehicles as have some developers of automated driving systems for trucks.
Those 900 nm class lidars are however showing resilience in the market in part because prices are approaching the sub-$500 mark and performance seems to be adequate for hands-off and eyes-off driver assistance systems. That’s the market Robosense is targeting for its new M3 lidar.
The M3 uses a 940 nm laser and similar MEMS beam scanning system that, like some others, can adjust the point density in different areas of the field of view. This allows it to put a higher density of points in the roadway area where the vehicle is driving, and lower density in the periphery. Robosense hasn’t revealed pricing for the M3 although it claims to be 40-50% cheaper than 1550 nm lidars. Since most 1550 nm sensors are still in the $1,000 range, the M3 is likely in the $500-$600 range. The M3 is claimed to be able to detect a 10% reflectivity target at 300 m, however, all such claims from any lidar vendor need to be examined to determine what size target is being used and where it is located.
Arduino Long Range Radar Announcements like this from Robosense and competitors such as Hesai and Innoviz show that there continues to be progress on driving down the cost and improving the performance of lidar sensors so that they can be applied to more vehicles in the coming years. As an active sensor that can accurately measure distance and speed, as well as do some degree of object classification, this is an important complement to cameras and radar in improving driver situational awareness and making driver assistance systems more capable and reliable.