12. Commissioning
MiR250 Hook User Guide (en) 01/2023 - v.1.2 ©Copyright 2021-2023: Mobile Industrial Robots A/S. 143
It is recommended to use less than 17 characters in the QR code. For example, 75mm-Cart_A is
11 characters long. If more than 16 characters are added, the QR code will change format, and it
will become more difficult to detect.
AprilTags
MiR250 Hook can be set to read AprilTags instead of QR codes. AprilTags are conceptually similar
to QR codes. However, they are designed for high localization accuracy by encoding far smaller
data payloads, allowing them to be detected more robustly and from longer ranges. When using
AprilTags, the robot still picks up and places carts the same way as with QR codes, but the
detection is more robust and faster.
Figure 12.3 Example of an AprilTag.
The recommended size of an AprilTag is 80 × 80 mm. The system accepts any other sizes between
80 mm to 300 mm. When you use a large sized tag, the real limit is whether the camera can see
the AprilTag or not.
It is required that at least 25 mm of empty white space surrounds the AprilTag.
The tag size is a global parameter so all tags used by MiR250 Hook must have the same sizes if
they are in the same site.
AprilTags can be generated in different patterns and classified in different tag families. Tag family
36h11 has 587 unique IDs and is the only tag family supported by MiR250 Hook. When MiR250
Hook is identifying carts, the ID of the AprilTag is used as the name of the tag as well as the cart.
The ID could, for example, be apriltag6.