Search

The production of grain and oil crops in the field has been the basic underpinning of the world. The rice-wheat and rice-oil tanker areas in southern China have been the main production areas of grain and oil crops in the field, with a planting area of up to 4.8 million hectares, providing for 55% of the food supply for the domestic market. Among them, more than 90% of fields are scattered in the individual small lands in the area (0-0.35 hm2) and irregular in shape, which requires convenient and frequent cross-district operations. In addition, the cultivated land in the rice-wheat and rice-oil tanker area is constantly in the process of wet-dry rotation, where the soil viscosity is easy to cause the wheeled agricultural machinery skidding, leading to the low operation quality and crop yield. The long-term use of wheeled agricultural machinery can aggravate the deep mud feet in the fields. Fortunately, the strong mobility of tracked agricultural machinery with the small turning radius and low grounding ratio can greatly contribute to avoiding the formation of plough bottom in the dry land, thus preserving the soil moisture from the drought and the destruction of hard bottom in paddy fields. The normal farming of paddy fields can be expected in the majority of areas, where the seedling emergence rate can still be as high as 80% to 90%. However, the current satellite autonomous navigation can normally be pre-configured the differential base station-building farmland map-planning global operation path, which failed to meet the requirements of convenient cross-area operation in a large number of scattered small fields. It is a high demand for the improvement of production efficiency and the threshold for accessible user friendliness. Ultra wideband (UWB, Ultra Wide Band) positioning and navigation belong to the low-cost and large-scale local navigation, which mainly has two ways: multi-UWB base station positioning navigation (3 or more) and dual UWB base station self-following navigation. However, some technical barriers have been confined to the autonomous navigation of agricultural machinery in the fields. At the same time, many efforts were focused mainly on the steering control during side slip in the autonomous navigation control of tracked agricultural machinery. It is still lacking on the occurrence of side slip to achieve the fast and steady steering at present. The control strategy of path correction planning can be fully considered to combine with the specific steering mechanism of tracked agricultural machinery. In addition, the absent operation in the center can cause the low operation efficiency in the narrow and irregular area of the field ridging, closed ridge, and set walking approach easy to repeat. Taking the tracked agricultural machinery as the research object, this study aims to propose a path tracking control system using fast steady-state steering. Taking the farmland boundary layout with the short-range UWB communication base station group as the reference path, the error self-diagnosis UWB navigation system was designed to achieve the high-precision and convenient autonomous navigation in small plots. The selection and optimization show that the best critical distance was 10 m from the farmland boundary to arrange the parallel agricultural machinery target operation path of the double UWB base stations outside the farmland. The static correction test showed that the tracking control error of the fast steady-state steering pat correction controller was less than 1 cm, with a coefficient of variation of less than 5%, whereas, the path correction time was less than 1 s, with the coefficient of variation of less than 3%. The dynamic correction test showed that the linear operation accuracy error of medium and low operating speed was less than 8 cm, and the linear working accuracy decreased slightly, with the increase of operating speed, but the linear operating accuracy error was not greater than 10 cm, with the coefficient of variation was less than 5%. Therefore, the error self-diagnosis UWB navigation system of tracked agricultural machinery in small land presented higher stability and excellent robustness than before, which can meet the needs of autonomous navigation of field agricultural machinery. The finding can provide a strong reference for the high-precision field autonomous navigation. [ABSTRACT FROM AUTHOR]

Unmanned aerial systems can widely be expected to realize the demand for “machine for man” in the field of precision agriculture. Particularly, the workforce is aging in most industrial countries, together with ever-increasing consumption, unreasonable exploitation of resources, and gradually deteriorated ecological environment. Correspondingly, these issues have posed a great challenge to sustainable agriculture in the future, as rapid information technology (IT) is emerging. Nevertheless, current farmland is distributed mainly on a small to medium scale after decades of land use regulation. By contrast, modern agricultural production requires a large scale, precision, and low cost in the direction of automation. Furthermore, most advanced technologies generally present relatively high cost, complex composition, and limited application, such as satellite, visual, and radar navigation. Therefore, it is highly necessary to explore a detection system with low-cost, high-precision, and easy-to-use navigation parameters. Fortunately, ultra-wideband communication (UWB) has received extensive attention in the field of wireless communication transmission in recent years. UWB-based positioning is one of the most promising high-precision technologies, providing convenience and new ideas for autonomous navigation in agriculture and industry. An important new initiative is also currently to vigorously promote land rectification and construction of high-standard farmland at this stage of agricultural production in China. This scheme has laid a solid foundation to realizing autonomous navigation for large-field agricultural machinery in the agronomic aspects. However, the current national large-field agriculture is still dominated by the individual management system and the family joint production contract responsibility system. Specifically, 90% of large-field agriculture is characterized by regional production on a small scale. Fragmented distribution is still the main body with a concentrated planting pattern of small fields at the 100-metre level, especially in the southern paddy fields. At present, there are two types of UWB positioning: short-range and long-range. The long-range module can reach more than 300m, up to 1,200m, and the optimal positioning accuracy can be known within 5cm. It indicates that the long-range UWB wireless range sensor can meet the demand for autonomous navigation and the driving of farm machinery in large fields in terms of range and detection accuracy. Furthermore, there is also local, moderately small-scale and scattered production, particularly on the large-field cultivation patterns in the southern paddy fields of China. The main factors are confined to the development of satellite, visual and radar navigation, including the high investment, complicated structure, limited applicable environment, and susceptibility to environmental interference. In this study, an improved signal angle of arrival (AOA) model was proposed to detect the navigation parameters under the reciprocal operation patterns of agricultural machinery in an unmanned environment in a large field. The UWB-based station tag was adopted as the detection sensor. Two arrangements were also designed to achieve fast and accurate detection of navigation parameters during the unmanned operation of agricultural machinery, including the double base station-body longitudinal double tag (TBZ) and double base station-body transverse double tag (TBH). The static test results show that the detection accuracy of navigation parameters improved significantly for the TBZ and TBH arrangements, as the tag or base station spacing increased. Specifically, the detection error of lateral deviation was ≤8 cm, and the heading deviation tended to be close to 0, but not greater than 1°. An orthogonal test was combined with the analysis of variance (ANOVA), thereby clarifying the significance of key parameters in the TBZ and TBH arrangements on the detection of lateral and heading deviation, and finally to determine the main and secondary factors for the optimal combination of parameters. The dynamic test results show that the detection accuracy of lateral and heading deviation decreased significantly, as the speed of the vehicle increased, where the error of lateral deviation was below 10 cm and the error of heading deviation was less than 3°, and the coefficient of variation was less than 10%. The finding can provide a sound reference for the development of unmanned systems with low cost, high precision, easy operation in modern mechanized agriculture. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Under the full amount of straw returning mode for wheat-maize rotation cropping areas in Huang-Huai-Hai Plain of China, not only the wheat straw mulch in the field is large, but also it has good toughness, and the effect of straw grinding is poor. In addition, the soil is more viscous. When the field operation is driven by the traditional wheel drive, it is easy to have straw winding and congestion, which is easy to break when seeding. At present, the corn seeder mainly adopts the ground wheel driving seeder and pneumatic seeder, and the land wheel driving seeder is transmitted by the earth wheel, driving the seed row shaft to rotate and arrange seeds, When the field soil viscosity and straw coverage are large, the driving part can not work normally. Pneumatic corn planter is mostly used in large farms, which are more expensive and not suitable for domestic use. In order to reduce the rate of missed seeding and improve the precision of maize sowing, it is necessary to develop a reliable and active corn precision seed metering control system. To solve these problems effectively, this paper takes a common spoon-wheel corn seeding device in the market as the research object, and a kind of active electronic control corn seeding meter system is designed. This electronic control system consists of control box, touch display interface, rotary encoder, GPS speed sensor, brushless DC motor, driver and commutator reducer. When the system works, the USART HMI four-wire touch serial port man-machine interface is used to input the theoretical expectation of the controller to the controller, using the GPS speed sensor to collect the working speed of the machine, in combination with rotary encoder, and the operation speed of the feeder is collected in real time. To ensure the quality of work and improve the ability to resist interference, based on the double closed-loop fuzzy algorithm, the PID parameters are self-adjusted to get the target speed of seed metering device. The corresponding PWM duty cycle of the controller is adjusted to achieve the real-time control of the motor speed through machine operation speed and achieve precise seed metering. The results of bench test showed that the variation coefficient of the actual rotational speed was less than 10.0% when the theoretical rotation speed was 6 ~ 54 r/min, and the actual rotational speed was small in the vicinity of the theoretical rotational speed, which met the control requirements. When the speed was 3 ~ 5 km/h under the set spacing value, the plant distance qualified index was > 94.0%, and the leakage index was < 3.0%. When the vehicle speed was 6 ~ 8 km/h, the plant distance was greater than 90.0%, and the seeding index was less than 4.5%. Field validation results showed: under the full amount of straw returning mode for wheat-maize rotation cropping areas in Huang-Huai-Hai Plain, when the maize row control system was in operation, the qualified index was greater than 87.75%, and the average was 90.89%, and the seeding index was less than 4%, with an average value of 2.54%. In comparison with the common spoon-wheel corn seeding device in the market, the qualified index was increased by 2.12 percentage points, and the seeding index was decreased by 4.32 percentage points, and the seeding performance was good, which met the requirements of corn agronomic planting. Under the full amount of straw returning mode for wheat-maize rotation cropping areas in Huang-Huai-Hai Plain of China, not only the wheat straw mulch in the field is large, but also it has good toughness, and the effect of straw grinding is poor, and in addition, the soil is more viscous. In this paper, the research of electronic control system for seed meters for maize planting can effectively improve the quality of the row and provide a reference for the development of high speed actuator control system. [ABSTRACT FROM AUTHOR]