Active Dual Line-Laser Scanning for Depth Imaging of Piled Agricultural Commodities for Itemized Processing Lines

• Published in: Sensors (Basel, Switzerland) Vol. 24; no. 8; p. 2385
• Main Authors: Ali, Mohamed Amr, Wang, Dongyi, Tao, Yang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09-04-2024; MDPI
• Subjects: 3D optical sensor; Accuracy; active line scanner; Agricultural commodities; Agriculture - methods; Animals; Brachyura - anatomy & histology; Cameras; Conveying machinery; depth imaging; Design; Farm produce; Food Handling - methods; Image Processing, Computer-Assisted - methods; Imaging, Three-Dimensional - methods; Interferometry; laser triangulation; Lasers; Light; Quality control equipment; Robotics; Scanners; Scanning devices; Sensors; surface profilometry; surface topography; Three dimensional imaging; Vision systems; active line scanner; 3D optical sensor; depth imaging; surface profilometry; laser triangulation; surface topography
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s24082385

The accurate depth imaging of piled products provides essential perception for the automated selection of individual objects that require itemized food processing, such as fish, crabs, or fruit. Traditional depth imaging techniques, such as Time-of-Flight and stereoscopy, lack the necessary depth resolution for imaging small items, such as food commodities. Although structured light methods such as laser triangulation have high depth resolution, they depend on conveyor motion for depth scanning. This manuscript introduces an active dual line-laser scanning system for depth imaging static piled items, such as a pile of crabs on a table, eliminating the need for conveyor motion to generate high-resolution 3D images. This advancement benefits robotic perception for loading individual items from a pile for itemized food processing. Leveraging a unique geometrical configuration and laser redundancy, the dual-laser strategy overcomes occlusions while reconstructing a large field of view (FOV) from a long working distance. We achieved a depth reconstruction MSE of 0.3 mm and an STD of 0.5 mm on a symmetrical pyramid stage. The proposed system demonstrates that laser scanners can produce depth maps of complex items, such as piled Chesapeake Blue Crab and White Button mushrooms. This technology enables 3D perception for automated processing lines and offers broad applicability for quality inspection, sorting, and handling of piled products.