Design and analysis of an aerial pollination system for walnut trees

Pollen is naturally distributed by wind or animals, but agricultural fields might suffer from lack of pollination due to a variety of factors. Artificial pollination is necessary for walnut trees because of dichogamy and lack of pollen in their early years. An airborne artificial pollination system is introduced and studied. As an automated solution, a quadrotor unmanned aerial vehicle (UAV) was fabricated for artificial pollination of walnut trees. The robot was designed, modelled and tested by releasing pollen over walnut trees. Airflow under the UAV was simulated using computational fluid dynamic (CFD) software. This simulation helped determine pollen streams under the robot to ensure that the released pollen reached the target trees. The quadrotor controller was designed and simulated in MATLAB, for system stability. For dynamic simulation, the robot was modelled in ADAMS software, and a co-simulation of MATLAB and ADAMS was used to tune and test the controller that was implemented for field experiments. The motion and stability of the UAV over farms with and without moderate winds were observed. To investigate the field performance of the proposed system, the pollination system is used on a walnut orchard. Different mixtures of pollen diluted with talcum powder were distributed over different groups of trees, using the quadrotor. After a few months, the results achieved on the trees were measured and the merits of the proposed system were evaluated.