Evaluating boom height control performance with variable boom roll damping in a suspended boom system on self-propelled sprayers
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In this research, a method for improving spray boom height stability was developed and tested. Self-propelled sprayers played a critical role in agriculture by applying chemicals to crops to control the presence of weeds and pests. The spraying process needed to be controlled in a manner such that the spray boom maintained the necessary target height for uniform coverage. Deviation from target height allowed outside factors such as wind to become more prevalent during chemical application which generated opportunities for spray drift to occur and potentially harm neighboring crops and environment.
On a suspended spray boom system, terrain influences on the chassis as well as height activation of individual wings induced boom roll that generated target height errors along the length of the boom. This research examined areas of opportunity for applying variable damping rates to boom roll with the intent of managing unwanted boom roll. Intelligent control of boom roll damping rates could minimize induced boom roll and improve target height control of the boom.
Virtual modeling software was utilized during the variable damping development process in order to simulate induced boom roll scenarios and evaluate successful application methods. Magnetorheological dampers provided the ability to further analyze variable damping methods on a full-sized sprayer in a field operating environment. A control system was designed using inputs from the sensors on the sprayer to detect induced boom roll and trigger increases in damping rates momentarily.
Increased damping rates proved to mitigate boom roll motion relative to the sprayer chassis. However, boom height control was only considerably improved when variable damping was applied during significant chassis roll events. In many instances, controlling boom roll motion with variable damping rates induced error into the chassis roll angle, therefore still creating boom height error.
Semi-active control of boom roll influenced the dynamics of both the spray boom and chassis. There were many critical factors that impacted the target height control of the spray boom. The suspension systems of the spray boom and chassis influenced one another and should therefore be considered jointly when developing methods for boom target height control.