Hilly and mountainous areas are characterized by complex, rugged terrain, steep slopes, narrow and winding operation spaces, and scattered natural or man-made obstacles such as field ridges and stone steps. These geographical features have posed substantial challenges to maneuverability, slope stability, and obstacle passing of conventional agricultural power chassis. It is an urgent demand for adaptable and efficient powered platforms in such regions. In this study, a micro articulated power chassis was specially designed to clarify the structural configuration and mechanism. The compact dimensions of 1650 mm × 1000 mm × 1100 mm were specifically improved for sufficient load bearing on narrow mountain roads, dense crop rows, and narrow field ridges. Mechanical articulated steering was adopted for the flexible folding and relative rotation between the front and rear frames. Turning radius was significantly reduced to fully meet the requirements of hilly areas, in terms of maneuverability, stability, and terrain trafficability. A multi-objective optimization model was constructed with three critical indicators as objective functions: the minimum turning radius (to enhance maneuverability in confined spaces), the maximum uphill stability angle (to prevent forward tilting during ascending), and the maximum downhill stability angle (to avoid backward tilting when traveling down slopes). These variables included the hinge position of the articulated structure and wheelbase parameters. Non-dominated sorting genetic algorithm (NSGA-II) was applied to optimize the Pareto best solution set. A wide range of schemes were used to balance these mutually conflicting goals. Systematic theoretical calculations and dynamic simulations were conducted on power transmission paths, articulated steering kinematics, and load distribution on sloped terrain. Three performance indicators were evaluated, including steering performance (evaluated by minimum turning radius and steering angle range), slope stability (quantified by longitudinal and lateral stability angles), and obstacle crossing (assessed by chassis posture during obstacle crossing). The simulation results demonstrate that the chassis was achieved the maximum articulation angle of 30.19°, indicating excellent maneuverability in narrow spaces; The maximum longitudinal and lateral stability angles reached 33.8° and 30.8°, respectively, indicating strong resistance to tilting on sloped terrain; when crossing obstacles with an average height of 165 mm, the chassis maintained continuous wheel grounding without any posture deviation, indicating excellent terrain adaptability. Field tests were conducted in a typically hilly agricultural area. The test data verified the reliability of the simulation. Once the rear frame was in an unconstrained state (consistent with actual operational conditions), both frames generated slight deflection due to uneven terrain loads and steering forces, directly leading to an increase in actual turning radius, compared with theoretical calculations. Geometric correction of the minimum turning radius was performed using measured frame deflection angles, where the average minimum turning radius was corrected to 2 145.55 mm. Additionally, the average articulation angle was 29.95° after measurement in field tests. It was highly consistent with the simulation (30.19°), thus verifying the accuracy of the first design. The chassis exhibited no overturning or sideslip under both unloaded and loaded conditions when traveling up and down a 24° slope or moving on a 15° lateral slope. Obstacle-crossing tests showed that the chassis successfully passed over 210 mm high field ridges and 150 mm high stone steps. Finally, a comparison was conducted on existing similar agricultural power chassis, in terms of maneuverability (minimum turning radius), slope stability (longitudinal and lateral stability angles), and terrain trafficability (maximum obstacle-crossing height). The micro articulated power chassis performed best to verify the practicability of the scheme, fully meeting the large-scale requirements in hilly and mountainous areas.

Brassica juncea var. tumida (tumorous stem mustard, TSM) is one of the most important vegetable crops of the Brassica genus of the Cruciferae family. However, the low level of mechanized harvesting cannot fully meet the large-scale production in the TSM industry. There is a high demand to shorten the stem cutting for the better integration of agricultural machinery and agronomy in the process of mechanized harvesting of TSM. In this study, a sliding-cut TSM harvester was proposed to optimize the operating parameters of its sliding cutter. Firstly, the structure and working principle were elaborated for the TSM harvester and root-cutting device, according to the agronomic requirements of the TSM harvesting. The sliding cutting was analyzed to compare the current shortened stem reciprocating and rotary cutting of TSM. The shape and structural parameters were determined to ensure the working strength of the sliding cutter. The installation of the sliding cutter was clarified, according to the force analysis. The contact parameters were calibrated between purple soil and slide cutter in the southwestern region. A soil-sliding cutter interaction model was established using EDEM software. A simulation was then implemented to analyze the impact of different operating speeds and cutter angles on the working resistance of the sliding cutter. The results showed that the angle between the sliding cutter and the working resistance was negatively correlated at the same speed, whereas, the working resistance of the sliding cutter was positively correlated with the working speed at the same sliding cutter angle. The soil tank test was conducted to verify the reliability of the parameter setting in the discrete element model, indicating the better performance of the sliding cutter. The cutting test was also carried out to optimize the test parameters, with the cutting resistance as the evaluation index, and with the operating speed, the angle of the cutter, as well as the cutting distance as the influencing factors. The results showed that the operating speed of the sliding cutter was positively correlated with the cutting resistance, whereas, the cutting distance was negatively correlated with the cutting resistance. The cutting resistance first decreased and then increased, when the tool angle was from 60° to 120°. The influencing factor of cutting resistance was ranked in the order of importance: operating speed, tool angle, and cutting distance. Furthermore, the operating speed of the sliding cutter was 0.1 m/s, the included angle of the cutter was 65°, and the cutting distance was 20 mm after optimized rounding. The values of cutting force in three repeated tests were 141.24, 156.32 and 150.65 N, respectively, where the errors were 9.8%, 21.53%, and 17.12%, respectively, compared with the theoretical of 128.63 N. Those values were 44.30%, 38.35% and 40.59% lower than the average cutting force in the Box-Behnken test. The optimal parameters of sliding knife operation were also verified. The findings can provide a strong reference for the mechanized harvesting of TSM, indicating the important engineering application.

China is a major citrus producer in the world. In the southern regions of our country, citrus is the fruit with the largest planting area and the most important economic status. However, citrus picking faces challenges like branch shading, difficulty locating fruit stalks, and varying stalk angles, causing low success rates and efficiency with traditional end effectors. This study takes navel oranges as the research object. This paper proposes a new type of end effector for fruit picking that mimics the manipulation of citrus fruits by fingers and passively cuts the fruit stalks. First, the physical parameters of the navel orange, such as its size, the diameter of the fruit stalk and the inclination angle, are determined. Then, the mechanical parameters such as the shear force and Young's modulus of the navel orange fruit stem are measured using the electronic universal testing machine. Based on the measurement data, the overall structure of the three-finger configuration end effector composed of two V-shaped cutting blades combined side by side is designed. The transmission mechanism of the crank-slider-rocker connecting rod mechanism is adopted to drive the reciprocating motion of the fingers, thereby prodding the citrus fruits and cutting the fruit stalks to achieve the picking function. For the design of the V-shaped cutting device, parameters such as the installation inclination angle of the V-shaped cutting blade, the opening angle of the blade, and the peak force range are determined through theoretical calculation. The peak cutting force under different included angle conditions is simulated and verified by using Ansys software. The simulation results show that the peak cutting force of the V-shaped cutting blade is the smallest when the included angle is 10° and the inclination angle is 6°. For the crank-slider-rocker transmission mechanism, its structural parameters are designed through theoretical calculation. Kinematic simulation analysis is carried out through Adams software, and it is determined that the transmission mechanism has a sharp rotation characteristic during the process of cutting fruit stalks. Finally, outdoor orchard picking tests are conducted on the trial-produced new type of end effector. The success rate of picking is 95.38%, the damage rate of navel oranges is 0, and the picking efficiency is 6.50 seconds pel orange. Meanwhile, a two-factor three-level orthogonal experiment is conducted on the citrus picking operation parameters and the post-harvest fruit stalk length. The variance analysis of the test data are performed using the Design-Expert software. The result shows that when the motor speed is 30 r/min、minhe post-harvest fruit stalk length of citrus is the shortest, only 19.8mm. This end effector can achieve rapid and non-destructive fruit picking under complex conditions where branches and leaves in the orchard are blocked, improving the success rate and efficiency of fruit picking. The research results can provide technical references for the development of the end effector of the picking robot.

Deep-pine operation is often required for the high-power tractor for traction at present, leading to low operating efficiency. More importantly, the total power consumption of vibratory deep-pine operation is ever-increasing with the increase of vibration frequency. Therefore, there is an urgent need to carry out research on the high-efficiency vibratory deep-pine machine for high operational efficiency and low energy loss. In this study, a deep loosening machine was designed to cooperate with the cutting and local vibration. The loosening mode was adopted for the cutting first and vibration second, i.e. the front deep loosening shovel was fixed to break the soil. The angle of entry was always in the position of the lowest soil resistance. The rear shovel was vibrated around the shaft to loosen the soil. The soil resistance was reduced to increase the range of loosening for less crushing of soil, in order to effectively reduce the consumption of vibration energy. The discrete element method (DEM) was used to analyze the effect of cut-and-vibrate deep loosening on soil disturbance. Hertz Mindlin with Bonding model in EDEM was used to establish the contact model among soil particles. The cut-and-vibrate and traditional deep loosening were simulated to compare at the same time. The experimental model of the deep-pine shovel was established using SolidWorks2022 software and then saved in a format suitable for EDEM. The model was also imported into EDEM for constraining, driving, and simulation. The motion state of the simulation model was divided into two strokes of breaking and vibratory deep loosening, according to the actual vibratory during deep loosening. The cut-and-vibrate co-operative mode effectively reduced the tillage resistance of the deep-pine machine; The one-factor test showed that the optimal intervals operating speed and vibration frequency were 0.9-1.1 m/s, and 9-15 Hz, respectively; The orthogonal test demonstrated that the optimal parameters were obtained for the deep-pine operation: operating speed 0.96 m/s, tillage depth 300.24 mm, and vibration frequency 11.43 Hz. The actual performance of drag reduction was tested on the cut-and-vibrate deep-threader. The simulation was also combined with the best operating parameters of deep-threading. The field tests were conducted, where the forward speed of the tractor was set at 1.0 m/s, the operating depth was 300 mm, and the vibration frequency was set at 9, 12, and 15 Hz. The field test showed that the cut-and-vibrate deep pine machine shared the outstanding drag reduction under the same speed and plowing depth, compared with the non-vibrating deep pine machine. The plowing resistance was reduced by 15.43%-37.56%; The power consumption was reduced by 8.87%-32.32%. The drag reduction was the most significant when the vibration frequency was 12 Hz. The plowing resistance was reduced by 37.56%, the power consumption was reduced by 32.32%, the solidity of the soil was reduced by 74.11%, and the soil disturbance coefficient was 56.32%, and the deep pine depth of 309 mm, deep pine was reduced by 15 Hz. The stability coefficient for the deep pine depth of 30.9 cm was 98.16%. The deep pine depth and its stability were in line with the industry standard. The cutting and vibration co-production deep pine machine shared outstanding performance to reduce the resistance and consumption. The finding can provide a new reference to optimize the vibration deep pine machine.