Due to the complex growth positions of dragon fruit and the difficulty in robotic picking, this paper proposes a six degrees of freedom dragon fruit picking robot and investigates the manipulator’s motion characteristics to address the adaptive motion issues of the picking manipulator. Based on the agronomic characteristics of dragon fruit cultivation, the structural design of the robot and the dimensions of its manipulator were determined. A kinematic model of the dragon fruit picking robot based on screw theory was established, and the workspace of the manipulator was analyzed using the Monte Carlo method. Furthermore, a dynamic model of the manipulator based on the Kane equation was constructed. Performance experiments under trajectory and non-trajectory planning showed that trajectory planning significantly reduced power consumption and peak torque. Specifically, Joint 3’s power consumption decreased by 62.28%, and during the picking, placing, and resetting stages, the peak torque of Joint 4 under trajectory planning was 10.14 N·m, 12.57 N·m, and 16.85 N·m, respectively, compared to 12.31 N·m, 15.69 N·m, and 22.13 N·m under non-trajectory planning. This indicated that the manipulator operates with less impact and smoother motion under trajectory planning. Comparing the dynamic model simulation and actual testing, the maximum absolute error in the joint torques was −2.76 N·m, verifying the correctness of the dynamic equations. Through field picking experiments, it was verified that the machine’s picking success rate was 66.25%, with an average picking time of 42.4 s per dragon fruit. The manipulator operated smoothly during each picking process. In the study, the dragon fruit picking manipulator exhibited good stability, providing the theoretical foundation and technical support for intelligent dragon fruit picking.

To solve the problem of low efficiency of manual harvesting of green soybeans and lack of adaptable harvesters, in this study, a brushing-type green soybean harvester was designed. The comb-brushing type green soybean pod harvesting equipment is composed of a front-mounted separation drum, a full-width material delivery mechanism, a negative pressure cleaning system, and a stalk-pod separation system. Based on the operation requirements of the front-mounted brushing-type detachment drum, the drum parameters, parameters of comb arrangement, and structural parameters of the comb, the force analysis in detachment was performed. By taking the pod detachment rate and damage rate as the response indexes, the rotational speed of the drum, the travel speed of the device, and teeth distance as influencing factors, a three-factor five-level orthogonal rotary combination test was carried out by the software Design-Expert. By establishing mathematical regression models for various influencing factors and evaluation indicators, conducting variance analysis and significance analysis on the response indicators of each factor, the optimal parameters were obtained at a rotational speed of teeth of 397.36 rpm/min, minimum axial teeth distance of 4.8 mm and travel speed of the device of 0.5 m/s. Field test results showed that, under the optimal parameter combination, the pod detachment rate was 94%, the damage rate was 3.04%, the harvesting efficiency was greater than 0.187 hm²/h, and impurity content was less than 7.8%, all of which met the design and usage requirements. The research results can provide a reference for the design of soybean harvesters.

During the field operation of rice combine harvester, the vibration generated by vibration component will only reduce mechanical reliability and yield, but also cause resonance in the human body, leading to a decrease in driving comfort and even damage to the driver’s health. To study the impact of combine harvester vibration on driving comfort, a certain type of tracked rice combine harvester was selected as the research object, and vibration tests were carried out based on vibration source analysis in the driving cab during field harvesting operations. The study showed that under the influence of field road conditions and crop flow, the operating speed of the engine, threshing rotor, stirrer, cutting blade, threshing cylinder, vibration sieve and conveyor were fluctuating, and their rotation and reciprocating motion would produce vibration excitation in the driving cab. A spectrum analysis was conducted on the acceleration signal of the driver’s cab, and it was found that vibration frequencies at three measuring points, namely the pedal, control lever, and seat, can reach up to 36.7~43.3 Hz. These frequencies can cause resonance in various parts of the driver’s body, such as the head and lower limbs, leading to symptoms such as dizziness, throat discomfort, leg pain, defecation anxiety, and frequent urination, and even affect vision of the driver. At the same time, a weighted root-mean-square acceleration evaluation method was used to evaluate the driving comfort of the harvester. The evaluation method showed that the vibration at the foot pedal (A_w1= 4.4 m/s²>2.5 m/s²) caused extreme discomfort, while the vibration at the seat (0.5 m/s²<A_w2= 0.67 m/s²<1.0 m/s²) and the control lever (0.5 m/s²<A_w3= 0.55 m/s²<1.0 m/s²) caused relatively less discomfort. This research can provide some reference for the optimization design of the joint harvester driver’s cab.

To address the problems of threshing loss and high impurity rate during sunflower oil harvesting, a vertical axial flow sunflower oil threshing device was designed. To reduce severe breakage of the sunflower plate and high entrainment loss rate when threshing by the traditional grating gravure sieve, a circular tube-type gravure screen was designed, and a contact model describing the grain rod, sunflower pan, and gravure screen was analyzed. The results show that reducing the diameter of the gravure screen round tubes can effectively reduce breakage of the sunflower pan. The range of the threshing gap, drum speed, and feed amount were determined by a single-factor test. Design-Expert software was used to design a response surface experiment: threshing gap, drum rotation speed, and feed amount were used as test factors, and the threshing loss rate of grains and the grain mass ratio of undersize grains were used as evaluation indicators. A regression model between test factors and evaluation indexes was established by variance analysis of the test results. A software-based numerical optimization function was used to reduce the loss rate of grains and increase the grain mass ratio of undersize grains. The optimal parameters of the threshing device were obtained by multi-objective optimization of all factors: the separation gap was 24.90 mm, drum speed was 244.14 r/min, feed amount was 2.95 kg/s, the threshing loss rate grains was 2.35%, and the grain mass ratio of undersized grains was 81.34%. This study can provide a reference for the design of a combined sunflower oil harvester threshing device.