吊杯式移栽机构中番茄穴盘苗运动分析优化与试验

Collision Optimization and Experiment of Tomato Plug Seedling in Basket-type Transplanting Mechanism

吊杯式移栽机构的投苗杯向栽植器喂苗时,番茄穴盘苗与栽植器的碰撞导致苗钵质量受损。为此,建立番茄穴盘苗与栽植器的接触力学模型和碰撞运动模型,用赫兹理论得到苗钵最大接触力方程,用冲量和冲量矩定理得到苗钵和苗茎与栽植器的碰撞运动方程,在此基础上用目标规划法建立多目标优化函数,得出栽植器角速度为1.18 rad/s和1.31 rad/s时,接苗角取72°和番茄穴盘苗的株高取12 cm,有利于减小苗钵质量损失。利用高速摄像试验观察碰撞运动,得出苗钵与栽植器的碰撞是弹塑性碰撞,苗钵和苗茎与栽植器的碰撞都会改变番茄穴盘苗的运动速度和姿态,使番茄穴盘苗与栽植器发生二次碰撞。苗钵破碎性试验表明,工作参数优化后的番茄穴盘苗质量损失分别为9.67%和8.43%,优于其它参数组合的试验结果。

The basket-type transplanter has the characteristics of punching a hole in the mulch film and planting the seedling simultaneously,and has been applied in the transplanting process of tomato seedling in Northwest of China. Mass loss of root lump is caused by collision between tomato plug seedling and planting device when feeding device of basket-type transplanter feeds the seeding to planting device. For this problem,maximum contact force equation of root lump was got after contact mechanics model of planting device built by hertziantheory and kinetic energy theorem; differential equation of motion for tomato plug seedling was got after collision model among root lump,stem and planting device built by impulse and impulse moment theorem respectively; then an objective function was built by using goal planning method between contact mechanics equation and differential equation of motion,and 72° was the optimal value for seedling angle when the angular velocity of planting device was 1. 18 rad/s and1. 31 rad/s by using the objective function. The height of tomato plug seedling was 12 cm after analyzing the relationship between collision point and drop angle of tomato plug seedling and movement velocity; it was benefit to reduce mass loss of root lump. The collision was elastic-plastic between root lump and planting device by using speed camera test to observe collision movement between tomato plug seedlings and planting device,the second collision of tomato plug seedling happened when root lump and stem collided with planting device,which meant theoretical research methods were reasonable. The root lump crushing test was carried out with the optimized operating parameters under the condition of angularvelocity of planting device was 1. 18 rad/s and 1. 31 rad/s,test results showed that weight loss of tomato plug seedling was 9. 67% and 8. 43%,respectively,which was better than the test results of other combinations of parameters.