Design And Research Of Compliant Manipulator For Deheading Shrimp

The increasing of the need of rich nutrient Penaeus vannamei make the poor shrimp processing equipment become increasingly prominent. In the part of deheading shrimp, the problems of intensive labor and high labor cost are seriously. The survey show there are patents related to the device for deheading shrimp at home and abroad, but their structures are complex and high cost and have no advantage at wide application when compared with the labor cost, so the application was limited. Through the study at the movement principle of compliant mechanism, the complexity of the deheading shrimp device can be reduced. This paper is about a compliant manipulator device for deheading shrimp to achieve the mechanized processing of deheading shrimp.The large amounts of data statistics and analysis established the mathematical model of the shrimp overall length and head length, and provided the theoretical basis to achieve precise position to dehead. Through analyzing the correlation between the yield of the headless shrimp and the mass of the complete shrimp, it found the correlation degree was 0.710, correlation is significantly positive, so the mass should be limited in later experiments to exclude the effect to the headless shrimp yield.By the biological characteristics and test in deheading shrimp it is found that the back, side and abdomen, the headless shrimp yield of this three different points of application were 65.18%, 63.61%, 64.11%, on the basis of headless yield and deheading effect, we can made sure the best point of application was the back. Through the comprehensive test of blade knife, knife no blade, tooth knife with different speeds for deheading, with the push pull meter pressure in the process of cutting head and the sensory quality of cutting section as evaluation indexs, determine the optimal knife form was blade knife, the lowest deheading velocity was 30mm/s. In order to improve the yield of headless shrimp as far as possible, through anatomizing dehead by hand and save more shrimp meat, it found that the shrimp head meat approximate to circular shape at the edge, comparing the experiment shows that the optimized trajectory can improve the yield of the headless shrimp.By combining the characteristics of the head test with compliant mechanism, the overall compliant manipulator device to dehead shrimps was designed. Through the experiment of anatomizing dehead shrimp and the “Bow-string Method” to determine the circular shape of shrimp head meat including the average radius was 50 mm, the horizontal size was 24.23 mm and vertical size was 14.88 mm etc. about the cutting cross-section of shrimp meat and determined the radius of the compliant manipulator device and every analytic functions. The motion simulation observed the movement trajectory of the compliant device proved the workable method, and the FEA((Finite Element Analysis) showed the point of stress and strain concentration and displacement which happen on the working compliant manipulator. It found that the stress concentration of the device was not serious, the maximum stress value was 4.012 Mpa.Through the manufacture and experiment of the compliant manipulator, the headless shrimp yield was improved to 70.78%. With the practice means, it proved the device was simple and convenient to operate so as to realize deheading shrimps by mechanization processing and provide a theoretical basis and practical guidance for the future research on deheading shrimp.