Abstract:Automatic head-tail and ventral-dorsal directional transportation is an important prerequisite for promoting the mechanized processing of freshwater fish. Based on horizontal vibration method and visual image recognition technology, an automatic head-tail and ventral-dorsal directional transportation device was designed. The principle of fish body rotation and the principle of head and tail advance were expounded by analyzing the force and motion state of fish body on the shaking table. The motion states of the fish on the shaking table were divided into four types, and the conditions for the fish to achieve head-tail directional transportation were analyzed. Combined with the image recognition technology, the guide mechanism, visual recognition system, elimination mechanism, V-shaped ventral-dorsal directional transportation actuator and V-shaped correction conveying mechanism were created to realize the automatic ventral-dorsal directional transportation. Finally, three typical freshwater fishes, crucian carp, Grasscarp and silver carp, were selected as the test objects, and the orientation completion time and success rate were used as the evaluation indexes. The effects of fish species, conveyor belt type, vibration amplitude and vibration frequency on the head-tail directional transportation of fish were explored, and the effects of fish species on the ventral-dorsal directional transportation were also explored. The test results showed that the theoretical calculation of the forward motion state of fish on the shaking table was consistent with the experimental results, it was proved that the theoretical calculation can effectively guide the actual head end orientation process. When the conveyor belt was only inverted triangle, the fish can complete the head-tail directional transportation. The effect of head-tail directional transportation was increased with the increase of vibration amplitude and frequency. When the vibration amplitude was greater than 160mm, the whole machine vibrated violently, so the optimal amplitude should be 160mm. When the frequency was greater than 5Hz, the change of orientation effect was not obvious, so the optimal frequency should be 5Hz. The ventral-dorsal directional transportation effect was determined by the conveying speed of the conveyor belt and the accuracy of machine vision recognition. The ventral-dorsal directional transportation time of all kinds of fish was kept at 15s, and the orientation success rate was stable in the range of 95%~97%. The research results can provide technical reference for the design and selection of technological parameters of fish automatic orientation device.