How sensor fusion enables AMRs to maneuver around factory floors efficiently
Three sensors in one Visual perception using a pair of cameras to produce stereoscopic images plus image processing based on AI and ML can enable the AMR to see the background as well as identify nearby objects. Sensors are available that include stereo depth cameras, a separate color camera, and an IMU in one unit. Stereo depth cameras like the Intel RealSense D455 RealSense Depth Cameras use two cameras separated by a known baseline to sense depth and calculate the distance to an object. One key to precision is using a sturdy steel framework that ensures an exact separation distance between the cameras, even in demanding industrial environments. The accuracy of the depth perception
Figure 4: This module
includes stereo depth cameras separated by 95 mm, a
separate color camera, and an IMU. (Image source: DigiKey)
matched to the depth imager field of view (FOV), improves the correspondence between the color and depth images, enhancing the ability to understand the surroundings. D455 depth cameras integrate an IMU with six degrees of freedom that enables the depth calculation algorithm to include the rate of motion of the AMR and produce dynamic depth awareness estimates.
alarms. They can vary between AMR makers and are often developed to reflect the specific activities in the facility where the AMR operates. Light strips are available with and without built- in audible alert mechanisms. For example, the model TLF100PDLBGYRAQP from Banner Engineering includes a sealed audible element with 14 selectable tones and volume control (Figure 5).
Lighting and sounding the way
algorithm is dependent on knowing the exact spacing between the two cameras.
Flashing lights and audible alerts for people near an AMR are important to AMR safety. The lights are usually in the form of a light tower or light strip on the sides of the AMR. They help the robot communicate its intended action(s) to people. They can also indicate status like battery charging, loading or unloading activities, intention to turn in a new direction (like the turn signals on a car), emergency conditions, and so on. There are no standards for light colors, flashing speeds, or audible
For example, the model 82635DSD455MP depth camera has been optimized for AMRs and similar platforms and has extended the distance between the cameras to 95 mm (Figure 4). That enables the depth calculation algorithm to reduce the estimation error to less than 2% at 4 meters. D455 depth cameras also include a separate color (RGB) camera. A global shutter for up to 90 frames per second on the RGB camera,
Figure 5: This light bar annunciator includes a sealed audible element (top black circle). (Image source: DigiKey)
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