Design and experiment of facility elevated planting strawberry continuous picking manipulator

Abstract

Strawberry picking manipulator is one of the key factors affecting the effectiveness of robot picking operations, elevated strawberries cultivated off the ground with hanging fruits provide convenient conditions for automatic strawberry picking. In order to adapt to the small space of elevated strawberry picking operation and to solve the problem of discontinuous picking process, a P-P-R-P type continuous strawberry picking manipulator was proposed. Based on the elevated cultivation mode and the clamping-shear picking method, the structural parameters and control system of the continuous picking manipulator were determined. The kinematics model of the continuous picking manipulator was established, the Jacobian condition number and performance of each joint in the picking operation were solved, and its flexibility and operability were analyzed. According to the growth characteristics of elevated strawberries, the picking simulation routes and operation cycles were set. Using MATLAB software, the simulation tests were carried out to analyze the working space of the continuous picking manipulator, the maximum speed and acceleration changes of each joint. In order to improve the success rate of strawberry picking, the operating parameters such as rotational speed, end picking angle and clamping position of the continuous picking manipulator were optimized using Box-Behnken test. Based on the simulation results and parameter optimization results, a continuous picking manipulator and motion control system were constructed and validation tests were conducted. The results showed that the average picking success rate of the continuous picking manipulator was 74.21 %, and the average picking efficiency was 12.87 s per piece. In conclusion, the P-P-R-P type continuous picking manipulator proposed in this study meets the automated operation requirements of strawberry picking and can be adapted to the elevated operating environment.