A parallel dual-arm robotic control method of white asparagus based on moving-looking-harvesting coordination and asynchronous harvest cooperation

Abstract

For an efficient, low-damage selective harvesting robot for white asparagus, a parallel dual-arm control method based on moving-looking-harvesting coordination and asynchronous spears harvesting cooperation is proposed. This approach aims to enable continuous, non-stop harvesting along the ridge while minimizing damage to the spears. Firstly, a parallel harvesting mode with independent harvesting areas for the dual arms was designed to reduce collisions between the robotic arms and simplify control complexity. Secondly, an efficient dual-arm cooperative harvesting algorithm, aimed at load balancing for multiple randomly distributed asparagus, was proposed. Then, a coordinated moving-looking-harvesting control strategy was developed to synchronize the robot’s movement, asparagus identification, and the harvesting operation using the two end-effectors. Finally, a prototype of the selective harvesting system was constructed, and its performance was evaluated in the field. The simulation analysis of the cooperative harvesting algorithm indicated that the shortest-time-based first-see-harvest (ST-FSH) path planning strategy outperformed two alternative methods. The dual-arm harvesting saved 45.17 % of the time and increased the harvest success rate by 3.19 % compared with the single-arm harvesting, while maintaining workload balance. Field trials demonstrated an asparagus recognition rate of 82.6 %, with an average detection time of 33 ms, a successful harvest rate of 92.3 % for recognized asparagus, and average robotic arm movement time and end-effector harvest time of 1.7 s and 5.7 s, respectively. The system achieved an asparagus damage rate of 7.2 %. The results confirm the feasibility of the proposed efficient, low-damage harvesting strategy, providing a solid foundation for the development of selective harvesting robots for white asparagus.