Optimization design for vibration reduction of micro planter and fertilizer machinery used in mountain area based on genetic algorithm

Abstract: In order to solve the problem of difficult manipulation of micro planting and fertilizing machinery powered by gasoline engine in the mountainous area, a method of vibration reduction was proposed in this paper. Primarily, a certain kind of micro planting and fertilizing machine was taken as a research subject to establish the mathematic model of the planting and fertilizing machine with five degrees of freedom, and the data of filed image spectrogram was collected through the experiment. Secondly, the simulation model of the system was built with Matlab/Simulink software; thereafter, the multi-objective optimization mathematic model was established taking four parameters i.e. the rigidity and damping between engine and rack, the damper rigidity and damping between rack and travel wheel as design variables and taking vertical vibration acceleration and elevation angular acceleration on the rack as evaluation criteria. Besides, genetic algorithm was applied to optimize the design of the system and the optimized results showed that root mean square of the vertical vibration acceleration on the rack of the optimized machine reduced by 32.9%, root mean square of the elevation angular acceleration reduced by 37.6%, and the maximum of objective function was reduced to 0.3349 from 0.3705 after optimization; based on this, structure components of the planting and fertilizing machine were redesigned according to the optimized design results including replacing the original iron track with rubber track, replacing the original damper, adding rubber plate connecting engine and rack. Finally, the comparison test of vibration before and after the optimization was conducted. In the test, one testing point was taken on each of the engine, the rack and the handrail, and the signals of the 3 testing points were collected using tri-axial acceleration sensor. Vibration tests were carried out under planting and fertilizing operating conditions at the depths of 4-5 cm and 9-10 cm respectively. The comparison test demonstrated that, at the depth of 4-5 cm, the vertical vibration on the engine reduced by 32.86%, the vertical vibration on the rack reduced by 28.31%, the vertical vibration on the handrail reduced by 42.35%; while at the depth of 9-10 cm, the vertical vibration on the engine, the rack and the handrail reduced by 37.36%, 18.49%, and 28.40%, respectively. Therefore, the conclusion can be safely drawn that the vibration of the optimized micro planting and fertilizing machine reduces dramatically under regular fertilizing condition, especially on the engine part, which has verified the validity of the vibration-reducing design. What's more, this method also provides a guideline to the research of vibration reduction for the products in the same category.