Autonomous navigation method based on RGB-D camera for a crop phenotyping robot

Phenotyping robots have the potential to obtain crop phenotypic traits on a large scale with high throughput. Autonomous navigation technology for phenotyping robots can significantly improve the efficiency of phenotypic traits collection. This study developed an autonomous navigation method utilizing an RGB-D camera, specifically designed for phenotyping robots in field environments. The PP-LiteSeg semantic segmentation model was employed due to its real-time and accurate segmentation capabilities, enabling the distinction of crop areas in images captured by the RGB-D camera. Navigation feature points were extracted from these segmented areas, with their three-dimensional coordinates determined from pixel and depth information, facilitating the computation of angle deviation (α) and lateral deviation (d). Fuzzy controllers were designed with α and d as inputs for real-time deviation correction during the walking of phenotyping robot. Additionally, the method includes end-of-row recognition and row spacing calculation, based on both visible and depth data, enabling automatic turning and row transition. The experimental results showed that the adopted PP-LiteSeg semantic segmentation model had a testing accuracy of 95.379% and a mean intersection over union of 90.615%. The robot's navigation demonstrated an average walking deviation of 1.33 cm, with a maximum of 3.82 cm. Additionally, the average error in row spacing measurement was 2.71 cm, while the success rate of row transition at the end of the row was 100%. These findings indicate that the proposed method provides effective support for the autonomous operation of phenotyping robots.