On-the-field simulation of fertilizer spreading: Part 3-Control of disk inclination for uniform application on undulating fields

摘要

To improve the quality of fertiliser centrifugal spreading, several control devices have already been developed to manage some disruptions occurring on horizontal fields. However, controls which manage disruptions on non-flat fields due to changes in tractor attitude (pitch and roll) have not been developed. In this study, the design of a new control device is developed for a twin-disk spreader by considering two new degrees of freedom for each disk and controlling the longitudinal and lateral tilts of each disk. These tilt corrections are derived from solving a constrained optimization problem. The cost function is the weighted sum of squared differences between the travelled distances of the particles obtained in the considered topography and those that would have been obtained on a horizontal surface. The weighting coefficients are provided by the experimental angular mass flow distribution. In order to reduce the computation time and expect the use of the method for a real-time correction device, a simplified optimization problem is proposed. The method is assessed for three ground surface configurations: longitudinal slope break, side slope break and combined slopes. The simulation demonstrates that using the new control device the application errors are lower than 10% while they reach up to 40% without tilt correction. Moreover the study shows that the problem of optimization uniformity on non-flat fields can be solved computing the travelled distance for only a very few number of particles of mean diameter. This helps in reducing the computational time required to solve the optimization problem and in making possible the development of real-time control devices.