System for vertical boom corrections on hilly fields

Classical vertical spray boom suspensions reduce the effect of roll on the spray distribution pattern by using gravity. On hilly fields, the boom is not positioned parallel to the ground, resulting in an uneven spray distribution pattern and causing harm to the boom when hitting the soil. This paper models mathematically systems that are able to follow the slope of the field. The structure of the models is studied, which turns out to be the same for the four investigated suspensions. The analytically determined models are validated. A controller is designed to create a slow active suspension, following the slope of the field and filtering soil undulations, causing unwanted boom roll. The controller is implemented on a laboratory set-up and on a real machine. It takes into account the dynamics of the suspension and adds damping. Despite the low power of the actuator, a good performance is achieved. Possible performance enhancement can be obtained by increasing the resonance frequency of the suspension and by making use of a more powerful actuator.