Development of tip orientation and embryo side recognition device for dent corn seeds

Abstract: Automatic directional packaging of corn seeds is the precondition for realizing mechanical directional sowing of corn. The key technology is tip orientation and embryo side facing recognition. Combined with the actual demand of directional packaging, tip orientation for dent corn seeds needs that the tip orientation success rate reaches 100% (i.e. the tip is completely directed), and the embryo side facing recognition accuracy rate is required to achieve a high level at the same time. In addition, combining the actual demand of agricultural production and popularization, the method and its dependent device used to realize the tip orientation and embryo side recognition method for corn seeds should have low requirements for the working environment and the operation cost should be reduced as far as possible. The existing methods of tip orientation and embryo recognition are difficult to fulfil practical requirement. On the basis of the available research results of the research team, taking dent corn seeds with horizontal posture and tip orientation incomplete exported by existing tip orientation device as research object, a tip orientation and embryo side recognition method for dent corn seeds based on laser switch and range theory was proposed and the tip orientation and embryo side recognition device was designed in this paper. According to the shape characteristics of the corn seeds, the corn seeds large head facing forward was removed by using the laser sensors and other components first to get the seeds tip orientation done, and then the embryo side facing direction of each corn seed was identified one by one and outputed. There were 2 main characteristics of the corn seed shape: shape characteristic and surface characteristic. The shape characteristic was that the outline of corn seed was similar to "V" shape with narrow tip and wide large head, the surface characteristic was that there was a germinal groove extending from tip to large head on the embryo side, and the germinal groove shape was approximately elliptical, and its long axis coincided with the symmetric axis of the embryo side, the reverse side was smooth. The tip orientation method was proposed based on the shape characteristics of corn seed and laser switch sensor. Referring to the shape characteristics of the corn seed, a "V" shape slot was designed, the corn seeds with tip facing forward could enter into the slot, while the corn seeds with large head facing forward could not enter the slot as the large head of seed would block the entrance, based on this difference, by means of a normally open laser switch sensor, a specific straight track and a push rod, the tip orientation of each corn seed could be identified and the corn seeds with large head facing forward were removed. When the seed's tip was oriented, it would be stayed in the slot with tip facing forward, and then the direction of embryo side would be recognized based on the surface characteristic and laser range sensor. With the combined of designed device and existing tip orientation device, a practical test bench was built and the orientation test for dent corn seeds was carried out to verify the actual effect of tip orientation and embryo side recognition method. The result showed that: the tip orientation success rate of existing tip orientation device was 89.6%, the embryo side recognition accuracy rate of designed device was 96.4% and the tip orientation success rate of designed device was 99.1%, which increased by 9.5 percentage points comparing with the existing tip oriented devices. The orientation method proposed in this study could basically realize the tip orientation of the corn seeds, and at the same time, the embryo side recognition accuracy rate could be reached to a high level. Generally, the tip orientation and embryo side recognition method and the device proposed in this paper have low requirements for working environment and low operation cost, which could provide a reference for automatic directional packaging and mechanically directional sowing of corn.