The construction of a scientific and effective soil pressure-sinkage model under sloped terrain condition has important guiding significance for the investigation of the soil compaction effect. It is also important for the theoretical calculation of driving resistance and design optimization of the undercarriage structure of hillside metal-tracked tractors (HMTs). The classic Bekker’s pressure-sinkage model does not consider the influence of the soil water content, bulk density, slope angle, and other factors; therefore, it cannot be directly used to investigate the relationship between the soil compaction and its sinkage under sloped terrain conditions. To solve this problem, this study first verified that the soil water content and bulk density exert significant effects on the pressure–sinkage relationship under flat terrain condition. Secondly, a pressure-sinkage test was carried out using the quadratic rotation orthogonal combination design method, and the soil water content, density, and slope angle were considered. The pressure-sinkage curves of sloped terrain soils from Yangling and Yangxian in Shaanxi Province, and Huining and Jingning in Gansu Province were obtained. Then the pressure–sinkage parameters (sinkage exponent, cohesive modulus, and frictional modulus) were calculated using the weighted least-squares method. Thirdly, the mathematical relationship between the parameters and the soil water content, bulk density, and slope angle was obtained. Then Bekker’s model was modified to obtain the pressure–sinkage model of sloped terrain. Finally, the control variable method under slope angle of 10°, soil water content of 10%, and bulk density of 2 mg·m⁻³ were used to validate the model. The results revealed that the root-mean-square error between the calculated pressure value of the model and the measured value of the film pressure sensor was 1.614, 1.601, and 0.822, respectively. In the dynamic operation of a hillside tractor prototype, the calculated pressures between the supporting wheels were close to the measured values. It indicates that the modified soil pressure–sinkage model is more suitable for calculating the force at the bottom of the track between the supporting wheels. It can also provide an important theoretical basis for accurately calculating the pressure–sinkage parameters of sloped terrain soil. Additionally, this approach could provide theoretical and technical support for the rational arrangement of HMT undercarriages to reduce the soil sinkage and driving resistance.

Hilly and mountainous areas account for approximately one-third of China’s total cultivated land, where crops such as tobacco, tea, fruit trees, and tall-stalk varieties such as sorghum are extensively cultivated. However, the level of mechanization in crop production remains relatively low, primarily because of the poor adaptability of existing agricultural machinery to rugged terrain. Conventional crawler chassis struggle to simultaneously meet the requirements of high ground clearance and operational stability, and their limited functionality further restricts efficient agricultural production in these regions. To address these challenges, this paper presents a novel high-clearance electric crawler chassis designed for greenhouse hilly and mountainous areas. The chassis employs a gantry frame with a ground clearance of 1550 mm, facilitating operation over tall row crops. It adopts a dual-motor independent drive scheme, ensuring the continuity of power and achieving in-place steering. A longitudinal center-of-gravity adjustment device driven by dual electric actuators allows the frame to shift ±350 mm relative to the crawler traveling system. Multibody dynamics simulations conducted in RecurDyn 2023 demonstrated that the chassis can achieve a maximum climbing angle of 38°, crossing for trenches up to 800 mm wide and can surmount vertical obstacles up to 300 mm high. Field tests carried out on slopes in accordance with Chinese National Standard GB/T 3871–2004 revealed that the longitudinal center-of-gravity adjustment device significantly enhanced the driving performance of the high-clearance crawler chassis. When activated, the maximum safe climbing angle increased from 30° to 35°, the maximum obstacle surmounting height at 3.6 km/h increased from 250 mm to 300 mm, and the maximum trench-crossing width increased from 600 mm to 700 mm. At 5.4 km/h, the trench-crossing width increased from 700 mm to 750 mm. The field test results were consistent with the simulation outcomes. The development of this high-clearance crawler chassis effectively reconciles the competing demands of high ground clearance and stability while improving overall versatility. It provides valuable technical insights for the design of safe and efficient agricultural machinery suited to complex terrains in hilly and mountainous regions, contributing significantly to the advancement of agricultural mechanization and modernization in these areas.

The driving speed of autonomous agricultural vehicles is influenced by surrounding cooperative vehicles during cooperative operations, leading to challenges in simultaneously optimizing operational efficiency, energy consumption, safety, and driving smoothness. This bottleneck hinders the development of autonomous cooperative systems. To address this, we propose a hierarchical speed decision control framework. The speed decision layer employs a maximum entropy-constrained proximal policy optimization (DMEPPO) reinforcement learning method, incorporating operational efficiency, energy consumption, safety, and smoothness as reward metrics to determine the optimal speed target. The speed control layer utilizes a Linear Matrix Inequality (LMI)-based robust control method for precise speed tracking. The experimental results demonstrate that the proposed DMEPPO achieved convergence after 2000 iterations and better learning performance, while the LMI-based controller achieved robust and responsive tracking. This architecture provides a theoretical foundation for speed decision control in agricultural vehicle cooperation scenarios. By considering aspects of speed decision-making control such as energy conservation, good solutions can be provided for the sustainable development of agriculture.

During contour rotary tillage on sloping terrain, the migration characteristics of the straw–root–soil complex directly affects the effectiveness of straw return and soil sustainability, but the underlying mechanisms remain unclear, hindering the development of specialized rotary tillage equipment. This study uses a self-developed bench test platform for rotary tillage on sloped terrain in hilly and mountainous regions and tracer method to systematically investigate the effects of slope gradient (5°, 10°, 15°), blade shaft rotational speed (200–300 r/min), forward farming speed (0.2–1.0 km/h), and straw content (0.4–1.2 kg/m²) on the migration characteristics of soil aggregates. The test results demonstrate that the forward farming speed is the most effective controllable parameter for suppressing the horizontal and lateral displacement of soil complexes. Increasing the speed from 0.2 km/h to 1.0 km/h can reduce the lateral displacement of straw by 65.3%. An increase in the rotational speed of the blade shaft intensifies the migration of the complex mass, with a notably increased displacement toward the downhill side under steep slope conditions (15°). The slope gradient is the dominant natural factor driving the asymmetric movement of the complex along the lower side of the slope. When the slope increases from 5° to 15°, the lateral displacement of the straw increases by 166%. Straw mulching effectively mitigates tillage-induced soil erosion. When the straw content increases from 0.4 kg/m² to 1.2 kg/m², the lateral soil displacement is reduced by 37.7% to 51.9%. Through orthogonal experiments and response surface analysis, the hierarchical order of the factors influencing soil complex transport was determined. In terms of soil lateral displacement, the primary influencing factor is the slope gradient. With respect to soil horizontal displacement, the dominant factor is the forward farming speed. Corresponding regression prediction models were developed. This study provides the first systematic evaluation of the transport mechanisms governing the straw–root–soil complex on sloped terrain under contour rotary tillage conditions, thereby establishing a theoretical foundation for designing specialized tillage equipment for hillside agriculture and performing quality control in the incorporation of crop residue.