UAVs-UGV cooperative boom sprayer system based on swarm control

Abstract

To increase the boom width of boom sprayers without adding to the overall weight, while ensuring the stability of long-span booms and improving the efficiency of boom sprayers, this paper proposes a UAVs-UGV(Unmanned Aerial Vehicle, Unmanned Ground Vehicle) Cooperative Boom Sprayer System(UCBSS) based on swarm control. The UCBSS integrates the high payload capacity of UGVs with the high maneuverability and terrain-independent characteristics of UAVs, simplifying the boom structure. Multi-rotor UAVs form a UAV swarm, which segments and suspends the boom, collaborating with the UGV to complete the spraying operation. A prototype with three UAVs and one UGV was developed, featuring a unilateral boom width of 21 m. To meet the operational requirements of the UCBSS, PD(Proportional-Derivative) feedback control is employed to achieve segmented boom balance, utilizing IMUs(Inertial Measurement Unit) installed on each boom section and RTK(Real Time Kinematic) positioning modules mounted on the UGV and UAVs. For UAVs-UGV cooperative motion control, the Adaptive Feedforward Compensation PD Feedback(AFCPF) control method is designed to control the UAV swarm. Reinforcement learning is used to train and optimize the control parameters. Field test were conducted to validate the UCBSS. The results show that in terms of boom balance, the average roll angle of the entire boom is 0.014 rad, with an average standard deviation of 0.007 rad, demonstrating high stability and mitigating the impact of boom elongation. Regarding UAVs-UGV cooperative motion, when using the proposed AFCPF control method, the maximum tracking error of the three UAVs is 0.204 m, representing a 68.3 % reduction compared to the PD control method. The overall average tracking error of the three UAVs is 0.109 m, a reduction of 60.6 % compared to the PD control method. The standard deviations are 0.030 m, 0.038 m, and 0.032 m, respectively, representing reductions of 55.2 %, 66.4 %, and 55.6 %, with an overall reduction of 59.1 %, verifying the effectiveness and stability of the proposed control method. The UCBSS proposed in this paper features a wide spraying span, simple structure, high operational stability, and easy scalability. Against the backdrop of rapid advancements in UAV and related technologies, it provides a novel approach to the development of high-efficiency, wide-span boom sprayers.