Design of a novel end-effector for robotic bud thinning of Agaricus bisporus mushrooms

Abstract

Removing some of the overly dense buds of Agaricus bisporus in factory-cultivated mushroom beds through a process called bud thinning, as required by agronomy, can improve the top-grade product rate and yield and reduce the waste of production costs. At present, however, the only manual way to complete the bud thinning process is time-consuming and labor-intensive, which limits the development of the Agaricus bisporus industry. Robotic bud thinning is an optimal alternative to this issue. In this paper, firstly, a novel mechanized bud thinning mode is proposed based on the growth characteristics of bud emergence along with a dynamic finite element analysis of swing and lifting subprocesses to validate the separation mechanism. Secondly, a swing force and angle acquisition system is established to analyze the dynamic process by which the bud detaches from the substrate, followed by confirming the required swing force and angle of 0.96–2.81 N and 6.6–18.6°, respectively. Thirdly, a new end-effector for bud thinning is designed, including the steering, separation, and removal mechanisms. Furthermore, the airflow suction structure of the removal mechanism is improved via CFD analysis along with improved flow velocity and the magnitude of negative pressure, resulting in a removal success rate of 96.7 %. A robotic bud thinning test bench with the designed bud thinning end-effector was built, and the experimental results showed that the bud thinning end-effector offered a success rate of 91.7 % and an average single mushroom bud thinning time of 6.2 s, which shows the effectiveness and feasibility of this method. The designed end-effector has high potential for integration into a robot to support the bud thinning process of Agaricus bisporus in factory mushroom production.