A Novel Multinozzle Targeting Pollination Robot for Clustered Kiwifruit Flowers Based on Air–Liquid Dual-Flow Spraying

Abstract

Manual pollination of kiwifruit flowers is a labor-intensive work that is highly desired to be replaced by robotic operations. In this research, a pollination robot was developed to achieve precision pollination of clustered kiwifruit flowers in the orchard. The pollination robot consists of five systems, including a multinozzle end-effector, a mechanical arm, a vision system, a crawler-type chassis, and a control system. The robot can select preferential flowers and then target their pistil to achieve precision pollination. First, statistical analysis of the dimensions of flower clusters and individual flowers was conducted to fit normal distribution curves, which guided the design of the spray coverage and combination intervals for the multinozzle end-effector. Second, optimal spray parameters were determined based on a three-factor, five-level quadratic orthogonal experiment, that is, air pressure of 70.4 kPa, rate of flow of 86.0 mL/min, and spray distance of 27.8 cm. A targeted pollination strategy was developed based on the preferential flower selection strategy and structure of the multinozzle end-effector. Field experiments were conducted in a commercial kiwifruit orchard to evaluate its feasibility and performance, and an average success targeting rate of 93.4% at an average speed of 1.0 s per flower was achieved. Furthermore, compared with artificial assisted pollination methods, it can improve the utilization rate of kiwifruit pollen with an average consumption of 0.20 g in every 60 flowers with an average fruit set rate of 88.9%. The validations demonstrated that the pollination robot can efficiently pollinate kiwifruit flowers and save pollen.