基于模糊PID的栽植直立度控制系统研究

Planting Verticality Control System Based on Fuzzy PID

摘要:

针对钵苗机械化移栽过程由于机器与土壤相对运动稳定性差造成的株距不均匀、直立度控制难等问题，本文以多连杆栽植机构为对象，提出了适用于不同株距的零速移栽方法，设计了基于模糊PID的蔬菜移栽机直立度控制系统。建立栽植机构运动学模型、分析水平补偿机构与行驶速度的运动关系，构建直立度控制系统模型，实现对水平速度补偿电机自适应调节，从而控制整个栽植机构水平移动。对栽植器水平速度进行实时补偿，使栽植器末端点水平速度与移栽机前进速度合速度为零，达到了优化栽植轨迹的目的。在Matlab/Simulink中搭建控制系统仿真模型进行效果验证，仿真结果表明，使用模糊PID优化的控制系统响应更快，精度更高、鲁棒性较好，响应时间为0.012 s，超调量为4.737%。在Matlab中使用控制规则优化栽植轨迹，控制系统工作后，在不同株距条件下栽植器末端点入土轨迹得到优化，鸭嘴栽植器进入土壤后的轨迹较为垂直，土壤内水平位移减小到12 mm以下，有利于种苗被零速栽入土壤中。当栽植频率为48株/min、栽植株距为200~700 mm时进行种苗移栽试验。试验结果表明，对比常规组，控制组中种苗直立度受株距和行进速度的影响明显降低，随着土槽速度增加，大多数种苗直立度为75°~90°，控制组平均直立度合格率为95.50%，平均直立度优良率达91.25%，优良率相对于常规组提升23.85%，满足不同株距条件对种苗栽植直立度的控制要求。

Abstract:

Aiming at the problems of uneven plant spacing and difficulty in controlling the uprightness due to poor relative motion stability between the machine and the soil during the mechanized transplanting of seedlings, taking the multi-link planting mechanism as the object, a zero-speed transplanting method suitable for different plant spacing was proposed, and a vegetable transplanter uprightness control system was designed based on fuzzy PID. Firstly, the kinematic model of the planting mechanism was established, the motion relationship between the horizontal compensation mechanism and the driving speed was analyzed, and the uprightness control system model was constructed to realize the adaptive adjustment of the horizontal speed compensation motor, thereby controlling the horizontal movement of the entire planting mechanism. The horizontal speed of the planter was compensated in real time so that the sum of the horizontal speed of the planter end point and the forward speed of the transplanter was zero, thus achieving the purpose of optimizing the planting trajectory. Secondly, a control system simulation model was built in Matlab/Simulink to verify the effect. The system simulation experiment showed that the control system optimized using fuzzy PID had faster response, higher accuracy and better robustness. The response time was 0.012 s and the overshoot was 4.737%. Then, control rules were used in Matlab software to optimize the planting trajectory. After the control system was working, the trajectory of the planter end point entering the soil under different plant spacing conditions was optimized. The trajectory of the duckbill planter after entering the soil was more vertical, and the horizontal displacement in the soil was reduced to less than 12 mm, which was conducive to the seedlings being planted into the soil at zero speed. Finally, the seedling transplanting comparison experiment was designed under the conditions of the planting frequency of 48 plants/minute and the planting spacing between 200 mm and 700 mm. Compared with the conventional group, the uprightness of the seedlings in the control group was significantly less affected by the plant spacing and travel speed. With the increase of the soil trough speed, the uprightness of most seedlings was in the range of 75°~90°. The average uprightness qualified rate of the control group was 95.50%, and the average uprightness excellent rate was 91.25%, which was 23.85% higher than that of the conventional group, meeting the control requirements for the uprightness of seedlings under different plant spacing conditions.