| The wide-narrow row rice pot seedling transplanting is a reasonable combination of rice pot seedling transplanting and wide-narrow row transplanting.It makes full use of the advantages of pot seedling transplanting does not damage to rice seedlings root and there is no reversion period after transplanting.It has the advantages of tiller and earing earlier,compared with traditional rice transplanting methods.The unequal row spacing of wide-narrow row rice seedlings transplanting has favorable conditions for improving the growth of rice such as ventilation and illumination.On the one hand,it can improve the ability of rice seedlings to resist lodging and prevent diseases;on the other hand,it can reduce the use of pesticides and environmental pollution.At present,there is a lack of a mechanism with clip pot seedling soil and a wide-narrow row transplanting,mainly due to the coupling effect of several factors,such as the rationality of the non-circular gear pitch curve,the size of the transplanting arm,the rationality of the structure,the shape of the trajectory,the attitude of the transplanting arm,and so on.It is difficult to design the transplanting mechanism with ideal transplanting trajectory and transplanting arm attitude.In order to obtain better transplanting trajectory and arm attitude under the premise of reasonable pitch curve shape of non-circular gears.The method for solving the parameters of planetary gear train with equal row spacing based on the concavity and convexity index of non-circular gears pitch curve is presented and the solution method of spatial unequal speed planetary gear train mechanism based on several key positions and attitudes is proposed.1)A method for solving and analyzing the transplanting mechanism of planetary gear train based on the judgment of the concavity and convexity of non-circular gear pitch curve is presented.According to the given planar trajectory,the global coordinate system is established.The gear train is simplified as a two-bar two-degree-of-freedom open chain mechanism(2R mechanism),and the relationship and the evaluation index between the concave and convexity of the non-circular gear pitch curve and the transmission ratio curve are deduced.The kinematic solution model of the mechanism based on the plane transplanting trajectory is established,and the range of variation of the center position of the gear train is established,that is the analytic region,and the characteristics of the gear train transplanting mechanism forming the plane trajectory are analyzed.2)According to the kinematics principle,the ideal transplanting trajectory of two-bar and two-degree-of-freedom open-chain mechanism is reconstructed and the transmission ratio of gear train is solved.What’s more,the calculation and distribution model of unequal speed transmission ratio is established,and the bar length,rod length ratio and gear train transmission ratio are obtained.The parameters of transplanting mechanism,such as the index of curve convexity of non-circular gear pitch,are established,and the information diagram of transplanting mechanism parameters which can form a given transplanting trajectory is established,which provides a reference for the design of gear train mechanism forming a specific trajectory.3)A method to solve the spatial unequal planetary gear train mechanism based on some key positions is presented.Based on the analysis of the working principle of the transplanting mechanism of the spatial unequal speed planetary gear train,the gear train is simplified as the two bar and two degree of freedom open chain mechanism(2R mechanism),and the seedling taking point is established.The kinematic model of open chain mechanism based on the spatial position and attitude of seedling clipping point,seedling pulling point and seedling pushing point is established.It can be used to calculate the parameters of the open chain mechanism,such as the length of the open chain mechanism,the attitude of the rotation axis,and the related initial angle.4)By the combined types of transmission gears with synthesizing staggered axes,it is concluded that the first stage adopts plane non-circular gear transmission,and the second stage adopts non-circular bevel gear transmission,which is the simplest space transmission form of the single planet frame seedling wide-narrow transplanting mechanism.The transformation between the link mechanism and the gear train is realized by attaching the unequal gear pair to the two-bar mechanism,combining with the reproduced transplanting trajectory of wide-narrow row pot seedling transplanting mechanism.The structure design of wide-narrow row pot seedling transplanting mechanism is realized in the combination transmission of non-circular gear and non-bevel gear.5)Simulations and tests conducted on a prototype confirmed the correctness of the theoretical model and the practicality of the design.The results show that the plantlet transplanting mechanism of earth-grafted rice with planetary gear train has a reasonable success rate and the theory of solving the problem is correct. |
