In Southeast Asia, many varieties of citrus are grown in hilly areas. Compared with plain orchards, it is difficult for large spraying equipment to move in hilly orchards. Small spraying equipment can enter hilly orchards, but their spraying power cannot make droplets penetrate into the canopy, resulting in low deposition rates within the canopy. As a kind of unstructured narrow space, the branches within the canopy are interlaced, thus a flexible manipulator that can move within the canopy is required. In this paper, a novel remote-controlled, cable-driven target spray robot (CDTSR) was designed to achieve a precise spray within the canopy. It consisted of a small tracked vehicle, a cable-driven flexible manipulator (CDFM), and a spray system. The CDFM had six degrees of freedom driven by a cable tendon. The forward and inverse kinematics model of the CDFM were established and then the semispherical workspace was calculated. Furthermore, while considering precise control requirements, the dynamics equations were derived. The experimental results demonstrated that the CFDM could move dexterously within the canopy with interlacing branches to reach pests and diseases areas in the canopy. The entire operation took 3.5 s. This study solved the problem of a low spray deposition rate within a canopy and has potential applications in agricultural plant protection.

The spraying of citrus to kill insects is a necessary part of the citrus planting process. Most of the currently used sprayers are cover sprays, which cannot achieve accurate and low-consumption spraying. Causing a lot of pesticide waste and environmental pollution. Aiming at the difficulty of precise spraying of citrus leaves, this paper proposes a soft spraying manipulator with good bending characteristics and flexible operation ability. The robotic arm consists of 6 joints and 2 arm segments. The two arm segments of the robotic arm are driven by two wire ropes and move in two orthogonal planes respectively. The PD controller design is designed. The joint state observers are constructed to predict joint angles, angular velocities, and other information. The dynamic simulation experiment is carried out, and the relationship between the wire rope tension and the spring elastic force changes with time, and the relationship between each joint angle changes with time. These make the wire-driven precise spray robotic arm potentially useful in agricultural spraying.