Automated oyster shucking. Part II. Computer vision and control system for an automated oyster orienting device

• Published in: Aquacultural engineering Vol. 37; no. 1; pp. 35 - 43
• Main Authors: Little, N E, Smith, OH, Wheaton, F W, Little, MA
• Format: Journal Article
• Language: English
• Published: 01.07.2007
• Subjects: Crassostrea virginica; Marine
• ISSN: 0144-8609
• DOI: 10.1016/j.aquaeng.2006.12.007

A mechanical system and a computer control system were developed and combined to automatically orient Eastern oysters, Crassostrea virginica. The mechanical parts of the system are detailed elsewhere (Little et al., 2007a) and thus will be only summarized here for clarity. This paper will focus on a description of the control system that senses the oyster's initial orientation using computer vision, then automatically reorients the oyster to a pre-specified orientation, and transfers the oyster to an exit conveyor while maintaining its orientation. The system was designed to handle wild, single oysters from the Chesapeake Bay. The system was designed to handle oysters having widely variable shapes and the initial target design speed was 60 oysters/min. The orientation algorithm developed for orientating oysters was based on research by Gird (1977) and Tojerio (1987). The mechanical and automated control systems were developed to work together to orient and transfer oysters onto an exit conveyor without losing their orientation. The computer control system consists of a computer, two driver units for two stepper motors, a digital camera, a mirror, and a lighting system. A camera with the help of a mirror collects both a side view and a top view of an oyster in its natural resting position. The image is analyzed by the computer and based upon the ratios of certain oyster physical dimensions the vision system determines the orientation of the oyster. The computer then issues commands to the stepper motor drivers and the system's pneumatic valves to automatically orient the oyster into the proper position and transfer it to the exit conveyor without losing its desired orientation.