Trajectory Synthesis and Optimization Design of an Unmanned Five-Bar Vegetable Factory Packing Machine Based on NSGA-II and Grey Relation Analysis

Abstract

To address the problems of the complex structure and single packing trajectory of a packing machine, a hybrid-driven, five-bar packing machine for same-point pickup and different points of release in unmanned plant factories was designed, and a GRA-C method based on grey correlation analysis and CRITIC weighting for the quadratic optimization of Pareto solutions was proposed. According to the agronomic requirements, the original track of the packing machine was designed. The trajectory synthesis of the packing mechanism was completed based on the NSGA-Ⅱ multi-objective optimization algorithm. To reduce the overall size of the five-bar mechanism and to ensure its good motion performance, an optimization model for trajectory synthesis was established, and the optimal solution was obtained via the quadratic optimization of the Pareto front solution. To further improve the motion performance of the mechanism, the angular displacement curve at the secondary trajectory points was fitted. Through a comparative analysis with the solutions of three special points in the Pareto front solution set, it was found that the standard deviation of the angular velocity and the standard deviation of the angular acceleration after the quadratic optimization were 26.07% and 24.42% lower than the average values of the other three groups of solutions, respectively. The final optimization results were used to design the vegetable packaging machine, and the trajectory was found to be in good agreement with the expected trajectory, with a root mean square error of only 0.74.

Design and Experiment of Automatic Transport System for Planting Plate in Plant Factory

“…As shown in Figure 9, the actuator mainly consists of a stepping motor (1), a support plate (2), a lift platform (3), synchronous belt drive components (4), a sliding rails and sliders for propulsion (5), and a grabbing mechanism (6). The grabbing mechanism, as the core of the output actuator, contains a rotating gripper (7), a clamping push plate (8), a rack and pinion (9), rotating slide rails and sliders for rotating sliders (10), a connecting rod (11), an electric pushing rod (12), a screw stepper motor (13), a telescopic push plate (14), a vertical fixing plate (15), a telescopic slide rails and sliders for rotating sliders (16), and a horizontal support plate (17). The stepping motor, synchronous belt drive components, and support plate sliding rails and sliders for propulsion together form a propulsion mechanism for the input actuator and are mounted above the lift platform.…”

“…However, it is this mode of production that leads to the need for a large amount of manual involvement in the cultivation processes, especially in the linkage of moving the cultivation plates up and down in the cultivation frames. This operational session is characterized by intensive and repetitive lifting operations and is dangerous for higher cultivation frames [16][17][18]. Therefore, in order to reduce the production cost of plant factories and also to automate the production systems of plant factories, mechanization of planting transport is an attractive way to improve the efficiency of plant factories and to reduce their costs.…”