The design and performance of a gimbal-type mounting for sprayer booms 2. Optimization model and validation

Abstract

An empirical approach had already indicated that the gimbal-type mounting is effective in reducing movement of a sprayer boom. This mounting involves springs and viscous dampers and it was concluded that the effects of these would more readily be optimized by calculation than by further experiments. An analysis was made of the dynamics of the gimbal mounting and a computer model developed by means of which the value of viscous damping could be optimized for a spring stiffness by searching for the minimum value of an output function integrated over a range of components of an input power spectrum. Power spectra for roll and yaw were calculated from data recorded at three speeds over the standard bumpy test track. The polar moment of inertia of the boom was determined by bifilar suspension. Optimum values of damping were computed for ranges of natural frequencies. The experimental gimbal mounting was rebuilt to facilitate tests at ranges of polar spring stiffness and polar damping coefficient. The conditions giving minima in the response obtained were found to agree well with the values predicted by the computer model.