Kinematic analysis and experiment of dual parallelogram multi-pole planting mechanism

Abstract: Hanging cup type transplanter is widely used because of its good protection to the seedlings, the strong adaptability to the soil and its flexibility of planting depth adjustment. In order to improve the quality of hanging cup type transplanter in transplanting seedlings, static trajectory graft seedlings test, planting perpendicularity comparison test and dynamic trajectory plant seedlings test have been designed according to the agronomic requirements. Through those tests, the relation model between the position of seedling mechanism and the accuracy of graft seedlings, the perpendicularity comparison model before and after plant, and the equations between the qualification rate of the plant perpendicularity and the overlap or deviate width of dynamic trajectory under the plant depth line have been established. The tests showed that the overlap or deviate width of dynamic trajectory under the plant depth line was an important factor to improve the qualification rate of planting. In order to meet those requirements, a double parallel multi-rod planting mechanism was designed. It was mainly composed of a horizontal movement control parallel mechanism and a vertical planting movement control parallel mechanism. Through analyzing and optimizing the structure data, the mathematical model and kinematic equation of this mechanism were built. In addition, based on Matlab-gui, the man-machine interaction program interface was written. According to the simulation results of computer program, a set of data including the length of the rod, the mounting location and the crank initial angle were optimized. Meanwhile, a seedling transplanter prototype was designed and made according to the data.By using a PCO.1200 hs camera produced by PCO Imaging Asia Private Trading Enterprise Limited, the movement of the recording spot in grafting seedling, in the static and dynamic trajectory of transplanting mechanism was observed with one photo being taken every 50 minutes. These pictures were analyzed through maximum intensity method of Ipp6.0 software to see if the transplanting mechanism met the requirements of the original design. The high-speed photography test of the grafting seedling showed that the send seedling mechanism could eject seedling to the center of the top of the planting device, and the planting device could receive it very accurately every time. The high-speed photography test of the static trajectory showed that the static trajectory tallied with its computer simulation perfectly. The high-speed photography test in dynamic trajectory showed that under the control of the transplanting mechanism, the endpoint in the bottom of the plant device oscillated quite a little (the design value was 1.05 mm) in horizontal direction under planting depth line. Since when the transplanter moves uniformly ahead, the plant device is planting seedling in zero-speed in horizontal direction under the control of the transplanting mechanism, the qualification of the transplanting is improved. These tests proved that the move laws of transplanting mechanism tallied with its original design, and the mechanism design, the data model, the software programme and the rational model were accurate. During the field test, when the accelerator pedal was shifted to the middle, the speed of the transplanter was around 0.3 m/s, one cycle plant takes 0.8 s, with rows spacing at 0.24 m, depth around 0.08-0.12 m. The accuracy of planting the seedling and the qualification ratio of the planting perpendicularity all reach 100%. The results of these tests proved that the double parallel multi-rod planting mechanism met the seedling transplanting requests of the rape, cotton, corn and so on. And the research method was proved to be accurate. All these can be the scientific basis for the design and analysis of the multi-rod transplanting mechanism.