Location control of automatic pick-up plug seedlings mechanism based on adaptive fuzzy-PID

Abstract: As one of the key components of a fully-automatic field transplanter, an automatic pick-up plug seedlings mechanism has important significance in reducing labor intensity, liberating labor forces, and improving efficiency of transplanting. For a new kind of push-out type automatic pick-up plug seedlings mechanism, this paper systematically studied the method of its location control, which was aimed at enhancing its location accuracy, ensuring its operation efficiency and improving its anti-interference. Through the analysis of mechanical structure characteristics of this new mechanism, it could be concluded that the location control for conveying potted trays is a key factor in ensuring accurate operation of the entire mechanism and finally highlighting its high efficiency. That is, if the accurate location of conveying potted trays is realized when other parts of this mechanism operate with the conventional time, compared with domestic common pick-up plug seedlings manipulators, the operation efficiency of this mechanism will be greatly increased. The location accuracy requirement in conveying potted trays was obtained based on the analysis and calculation in details. At the same time, the control accuracy of the potted trays conveying system under the simple closed loop stepping location control was identified theoretically. This paper then analyzed the limitations of the stepping location control system under a simple closed loop control, fixed parameter PID control or fuzzy control, and the adaptive Fuzzy-PID control algorithm was proposed to be used to achieve the location control. In this paper, the adaptive Fuzzy-PID controller was designed, and the transfer function of the closed loop stepping location control system was constructed, and finally the modeling and simulation analysis in the Matlab were carried on, as well as the system debugging experiment. The simulation analysis showed that the response time of the adaptive Fuzzy-PID control was 0.192s, and that of PID control was 0.359s. In the interference of a disturbance signal, the disturbance overshoot of the adaptive Fuzzy-PID control as a percentage of disturbance signal amplitude was 0.88%, and that of PID control was 10%, so the former was far less than the later. The comparative analysis from above showed that the adaptive Fuzzy-PID control system had a faster response and better anti-interference, so it will have a distinct advantage in working in a complex field operation environment. The system debugging experiment then showed that the maximum relative location error of conveying potted trays under the adaptive Fuzzy-PID control was 0.27%, which was lower than the maximum relative error allowed in conveying potted trays. That is to say, the adaptive Fuzzy-PID controller can satisfy the location accuracy requirement of conveying potted trays. In sum, using an adaptive Fuzzy-PID control algorithm to fulfill the stepping location control of conveying potted trays can enhance the location accuracy, and improve the anti-interference and the system stability, which ensures the efficient operation of this automatic seedling pick-up mechanism and makes it suitable to the complex field transplanting operation environment. This paper provides not only reference and basis for the whole control system's development of this automatic seedling pick-up mechanism but also a new solution for the control system of other seedling pick-up mechanisms or transplanters to adapt the field transplanting operation environment with multiple nonlinear influence factors.