Design and experiment of the end effector for citrus picking imitating finger plucking and cutting

China is a major citrus producer in the world. In the southern regions of our country, citrus is the fruit with the largest planting area and the most important economic status. However, citrus picking faces challenges like branch shading, difficulty locating fruit stalks, and varying stalk angles, causing low success rates and efficiency with traditional end effectors. This study takes navel oranges as the research object. This paper proposes a new type of end effector for fruit picking that mimics the manipulation of citrus fruits by fingers and passively cuts the fruit stalks. First, the physical parameters of the navel orange, such as its size, the diameter of the fruit stalk and the inclination angle, are determined. Then, the mechanical parameters such as the shear force and Young's modulus of the navel orange fruit stem are measured using the electronic universal testing machine. Based on the measurement data, the overall structure of the three-finger configuration end effector composed of two V-shaped cutting blades combined side by side is designed. The transmission mechanism of the crank-slider-rocker connecting rod mechanism is adopted to drive the reciprocating motion of the fingers, thereby prodding the citrus fruits and cutting the fruit stalks to achieve the picking function. For the design of the V-shaped cutting device, parameters such as the installation inclination angle of the V-shaped cutting blade, the opening angle of the blade, and the peak force range are determined through theoretical calculation. The peak cutting force under different included angle conditions is simulated and verified by using Ansys software. The simulation results show that the peak cutting force of the V-shaped cutting blade is the smallest when the included angle is 10° and the inclination angle is 6°. For the crank-slider-rocker transmission mechanism, its structural parameters are designed through theoretical calculation. Kinematic simulation analysis is carried out through Adams software, and it is determined that the transmission mechanism has a sharp rotation characteristic during the process of cutting fruit stalks. Finally, outdoor orchard picking tests are conducted on the trial-produced new type of end effector. The success rate of picking is 95.38%, the damage rate of navel oranges is 0, and the picking efficiency is 6.50 seconds pel orange. Meanwhile, a two-factor three-level orthogonal experiment is conducted on the citrus picking operation parameters and the post-harvest fruit stalk length. The variance analysis of the test data are performed using the Design-Expert software. The result shows that when the motor speed is 30 r/min、minhe post-harvest fruit stalk length of citrus is the shortest, only 19.8mm. This end effector can achieve rapid and non-destructive fruit picking under complex conditions where branches and leaves in the orchard are blocked, improving the success rate and efficiency of fruit picking. The research results can provide technical references for the development of the end effector of the picking robot.