# Low-cost 4-DoF arm RoArm-M2-S achieves vision-guided writing tool reorientation and color sorting

- Source: arXiv cs.RO
- Published: 2026-11-05T05:00:00.000Z
- RoboHot: https://robohot.news/en/items/b5ahngyzacd5icmlcpck9k8ig
- Original: https://arxiv.org/abs/2608.15968

## Summary

The roughly $200 Waveshare RoArm-M2-S four-degree-of-freedom robotic arm, under a fixed overhead camera, uses a YOLO11n-OBB detector, an ArUco reference pose, and a color classifier to perform color sorting of writing utensils without a wrist rotation joint. For utensils deviating more than 45 degrees from the fixed approach direction, corrective sweeps bring them into a graspable pose within at most 4 attempts. In 196 single-utensil trials, 176 (89.8%) landed in the correct color bin; of the 20 failures, 19 were grasp slips or missed grasps and 1 was a color mislabel.