Modeling of a Chain-Load Control System for Potato Harvesters
ABSTRACT POTATO tuber damage due to mechanical harvesting methods is a significant problem for growers nationwide. In Washington State alone, tuber damage can result in grower income losses of over $6 million annually. Automatically maintaining a relatively constant primary chain load on the potato harvester results in uniformly full conveyor chains and minimum tuber damage as demonstrated by Hyde et al. (1983 a). A numerical model of the primary chain dynamics and load control system was developed. Model stability and performance were analyzed and compared with a field tested on-off control system. In addition, proportional and proportional-integral control methods were investigated. Proportional-integral control characteristics proved to be superior to the on-off method of control, while proportional control alone was the least desirable.