Development of Automatic Length Measurement System for Fish Body with Laser Sensors

• Main Authors: Huang, Jun-Qing, 黃駿青
• Other Authors: Hsieh, Ching-Lu
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5z8xqn

碩士 === 國立屏東科技大學 === 生物機電工程系所 === 106 === In order to meet requirement from International Organizations, each far sea vessel needs report fish length of its catch. Currently, the length is manually measured and recorded which is laborious, time consuming, and tends to manual errors. Therefore, argues occur occasionally between vessel managers and government agents. It needs new approach to improve. This study developed an automatic measuring and recording system for fish length which consists of object detecting unit, length measuring unit, guiding slider (chain type or pneumatic type), PLC (programmable logic controller), and PC (personal computer). The system detected and measured fish length, once the carried fish enter the detecting zoon on deck. Fish length was measured by sensing the object existence with a sensor on the slider. The lasting time of detected object (fish) and the slider speed were multiplied to obtain fish length. This operation was processed by a computer program in Visual Basic. The length data can also be saved in a file along with date, time, and its catch position (longitude and latitude) when worked with GPS (global positioning system). The system was tested in room with four boxes of length of 37, 63, 90, and 126 cm. The accuracy in length was about 95 to 97%, according to test results. Factors influencing on the accuracy included response time of the sensor, moving speed of the slider, and the distance between sensor and object. Real fish (yellow fin tuna) samples were also tested in room and in a CT7 vessel. The length accuracy was about 90 to 95% when a modified coefficient was adopted in the computer program. Detection part of fish (such as fish back or fish abdomen), the height of sensor position, luminance of detection environment were the factors affecting the accuracy. Test result also showed the automatic system completed one reading in 3 second which reduced the time in more than 50% compared to the manual operation. Meanwhile, the system also can avoid the manual record error and work with electronic monitoring system (EMS) by sending catch data thru satellite in real time from far sea to control center on land so as to offer better quality of length data for fishery and nature resource management.