This paper provides a review of path-tracking strategies used in autonomous agricultural vehicles, mainly from two aspects: vehicle model construction and the development and improvement of path-tracking algorithms. Vehicle models are grouped into numerous types based on the structural characteristics and working conditions, including wheeled tractors, tracked tractors, rice transplanters, high clearance sprays, agricultural robots, agricultural tractor–trailers, etc. The application and improvement of path-tracking control methods are summarized based on the different working scenes and types of agricultural machinery. This study explores each of these methods in terms of accuracy, stability, robustness, and disadvantages/advantages. The main challenges in the field of agricultural vehicle path tracking control are defined, and future research directions are offered based on critical reviews. This review aims to provide a reference for determining which controllers to use in path-tracking control development for an autonomous agricultural vehicle.
19 April 2023 in Computers and Electronics in Agriculture
Field surface fluctuations and crop residues can induce significant random vibrations of no-tillage planters, which may negatively affect seed implantation stability and crop yield. At present, it is difficult to understand the extent to which the working components of a no-tillage planter affect its vibration, and how to reduce the influence of vibration on the quality of the no-tillage seeding is a critical problem. The main factors affecting the vibration of no-tillage planters were studied by tractor engine vibration source impact analysis experiments, no-tillage planter structural vibration source experiments, and light and heavy no-tillage configuration vibration source analysis experiments. The results show that the effects of the ground wheels, the fertilizing and stubble breaking and cleaning devices, the packer wheels, and the power output shaft gradually diminish. The resonant frequencies of the tractor–no-tillage planter system were 68.36 Hz and 67.38 Hz. Furthermore, this study provided a relative assessment of the correlation between planter downforce and its vibration intensity. To sum up, the multi-source vibration impact analysis method proposed an effective method for studying the contribution of individual components to the overall vibration behavior of no-tillage planters. It provides a theoretical basis for the optimization design of the vibration damping system.
In response to the issues of high cost, limited detection accuracy, and significant measurement errors inherent in conventional manual techniques used to measure straw cover weight under the conservation tillage method, a dedicated straw cover weight detection machine was developed in the current study. This machine included a critical straw suction device that utilizes negative pressure to collect straw within a defined area. The efficiency of straw collection is affected by suction chamber structural parameters and transport pressure. With crushed corn straw as the research subject, the theoretical calculation of straw suspension velocity was used to determine the wind duct diameter, perform the initial design of the suction chamber structure, and select the appropriate fan. After conducting preliminary experiments, single-factor optimization tests, and orthogonal rotation experiments, we analyzed the flow field distribution patterns and identified the critical parameters for the straw cover weight suction unit. We found that the fan should operate at a speed of 2900 r/min, the diameter of the straw outlet should be 200 mm, the vertical height of the suction chamber should be 536 mm, and the bottom diameter of the suction chamber should be 800 mm. The optimization results were validated through simulation tests and bench tests, yielding an average near-ground airflow velocity of vj = 9.03 m/s and an average outlet airflow velocity of vo = 34.27 m/s, meeting the basic requirements of the suction unit. This study could provide a new approach and technical support for the automated detection of straw cover weight in conservation tillage areas.