Transactions of the Chinese Society of Agricultural Engineering, the 1st in Agricultural Engineering, is supervised by China Association for Science and Technology, and sponsored by Chinese Society of Agricultural Engineering. It aims to introduce the latest scientific achievements and developing trends of Agricultural Engineering and provides the academic developments abroad and domestic of the discipline. The scope covers agricultural water-soil engineering, agricultural information and electrical technology, agricultural products processing engineering.
The journal is included in EI, JST, Pж(AJ), CA and CSCD.
Editor-in-Chief Zhu Ming
Deputy Editor-in-Chief Wei Xiuju Zhang Ruihong Xi Weimin Wang Liu Wang Yingkuan Li Pingping Ying Yibin Tong Jin Yun Wenju Zhao Chunjiang Kang Shaozhong
Corn is one of the main grain crops in China, and it is also an important part of farmers’ income source. In recent years, in order to achieve the goal of increasing agricultural maize income, corn planting areas in the middle east of Gansu have used a technology called the whole plastic film mulching on double ridges against the drought, and it provides an effective technical approach for a steady increase in the yield of maize in the arid regions. According to statistics, by the end of 2013, the rate of corn mechanical harvest was 49%, and till 2016, the rate of corn mechanical harvest reached 63% in China. On the whole, the corn mechanization level in China has been greatly improved, but the harvest of maize in Gansu Province is mainly based on artificial harvesting, and mechanized harvest has lagged behind the national average level. Except some small plots that cannot use combine harvester, plastic film has become one of the main reasons limiting the application of corn combined operation machinery. If we continue to use the machine with horizontal roller commonly used in China at present for harvesting, then after stripping the collection process of corn stalk cannot be completed. Therefore, the ordinary type of corn combine harvester with horizontal roller is not suitable for agricultural production in the arid regions. To adapt to the cropping patterns of the whole plastic film mulching on double ridges in the arid regions, and solve the problem that the corn plant can not be fed continuously into the header of the harvester during the harvesting process, as well as the high loss rate issue of traditional corn harvester, a kind of self-propelled corn combine harvester for harvesting ear and stalk was designed in this paper. This machine cut two rows at one time, and uses the vertical snapping rolls to grab the corn ear from the corn stalk, and the corn ear is delivered at the middle of the cutting platform; behind the vertical snapping rolls there is a shredding device, and the corn stalk chopped by the shredding device is conveyed by the conveyer on the side of the combine harvester. This arrangement on the cutting header realizes the whole plastic film mulching on double ridges for two-row cutting and reaping both corn ear and stalk for corn combine harvester, and the grain loss is reduced. Because of the existence of plastic film, the corn stalk after picking cannot be smashed and returned to the field with corn stubble. However, the vertical snapping rolls can solve this kind of defect. When the vertical snapping rolls worked, the stalk is output from the vertical snapping rolls, so it is suitable to recycle the stalk. Compared with the horizontal snapping rolls, the vertical snapping rolls can reduce the weight of the cutting platform and shorten the length of the machine. At the same time, the turning radius is reduced correspondingly, the turning is more flexible, and the machine can walk better on the double ridges. In addition, the gripping delivery mechanism adopts a holding and convey chain on one side, and the other side is an eccentric elastic tooth type shifting wheel, so the weight of the cutting platform is further reduced. And the machine can complete the function of corn ear’s picking, conveying, peeling and collecting at one time, as well as the stalks cutting, kneading, chopping, throwing and collecting. The field experimental results show that the grain loss rate is 1.8%, the ear loss rate is 2.4%, the grain damage rate is 0.77%, the qualified rate of cutting corn stalk is 92.6%, and the husking rate of corn is 95.1%, when the machine speed is 4.5 km/h, the speed of vertical snapping rolls is 1 100 r/min, and the speed of shredding device is 1 584 r/min. And the experimental results meet the design requirements of combined operation machine.
Different land use types are mixed with each other inside the rural settlements. They are in spontaneous, loose and chaotic development situations. Extensive and inefficient land use is common. Through the research of internal function structure of rural settlements, we can identify the existing problems to provide guidance for the quantitative and spatial arrangement of different land use types, thus enhancing land use efficiency to achieve the optimal goal. In the paper, the land use internal structure classification system of rural settlements was established from the perspective of function. We tried to master the internal land use structure of rural settlements in a microcosmic perspective. Following the principles to show the rural land characteristics, so as to provide guidance for land management and reflect social-economic development, we divided the internal land use structure into production function land, living function land, ecological function land and potential function land. The production function land was divided according to industrial types. The living function land was divided according to residents’demand. The ecological function land was divided according to ecological service types. The potential function land was divided according to the consolidation costs. Eventually, the land use classification system consisted of 4 first-level classes, 10 second-level classes and 37 sub-level classes. It could satisfy the research needs of small scale and high precision. Based on the established classification system, we investigated the rural settlement of Daxingzhuang Village, Pinggu District, Beijing City through field survey and participatory evaluation method, acquiring its internal land use structure. After the comparative analysis between land use functional structure classification of rural settlement and
Current Land Use Classification (GB/T 21010-2007), we found that there was a significant differentiation between the 2 classification systems: 14 land use types in current land use classification and 28 land use types in land use functional structure classification of rural settlement. The land use functional structure classification of rural settlement in this paper refined the current land use classification. It focused on the actual land use condition, and weakened the ownership property of internal land use types, such as urban land, rural settlement land and independent industrial and mining land. This classification system has achieved the purpose of accurately characterizing rural settlement land with fewer land use types, and highlighting the dominant functions of various land use types. The comparison results showed that living function land accounted for a relatively stable proportion and formed the basic structure of rural settlements. However, the sub-classification of housing land, such as the idle housing land, could provide foundation for internal land use potential development, which could promote the improvement of rural settlement land use efficiency and the land use standard measurement. Besides, the land use functional structure classification of rural settlement could also calculate the multiple functions of rural settlements. The production function land in Daxingzhuang Village accounted for 34.73%, the living function land 53.53%, the ecological function land 4.06%, and the potential function land 7.68%. It could not only satisfy the demands of peasant, but also propel the rural settlement land consolidation, thereby promoting the internal land use investigation, planning and management, and the coordinated development between urban and rural areas.
In order to improve the performance of trajectory tracking control for agricultural tracked robot (ATR) in which the geometrical center does not coincide with the centroid, this paper comparatively analyzes the performance of all kinds of control methods for ATR, such as PID (proportion, integral, derivative) control, sliding mode control (SMC), and neural network control method. The ATR model is regarded as a cascaded system consisting of the drive motor equations and the mobile ATR kinematics equations. Through analyzing both the kinematic model of ATR and the unique features of motor driven model, this paper establishes a motor driven model and a position and orientation error model which is based on the tracking coordinate system and inertial coordinate system. And then a sliding mode control module and an integral sliding mode switching function (ISMSF) are proposed as well. Furthermore, this paper develops an adaptive sliding mode control (ASMC) based on ISMSF, which is composed of equivalent control and nonlinear switching control. The ASMC can feed back the position and orientation errors as well as the time-varying parameters of the drive equation to the controller, based on which it can calculate the expected angular velocities of the left and right driving wheels and drive ATR to smoothly run. The simulation results show that under the adaptive sliding mode control, the angular velocity for driving wheel can reach the ideal value in 0.375 s, while the common sliding mode control requires 0.75 s to achieve a relatively stable state with the chattering phenomenon. Besides, when the biggish position and orientation error appears in the system, ASMC can limit the integral function to keep the system from too large overshoot; when the less position and orientation error appears in the system on the other hand, ASMC will prevent the system from chattering. Especially, when ATR tracks the fold line path, the initial position and orientation for the target trajectory are [0, 0, π/4]
T; the velocity for ATR is 2 m/s; and the initial position and orientation for ATR start from [−2, −2, π/4]
T. The position and orientation error for ATR can converge to 0 in a relatively short period of time; the tracking error for ATR ranges from 0 to 0.04 m along the distance error in the direction of motion, and from −0.07 to 0.07 m along the lateral distance error; and the heading error ranges from −0.02 to 0.045 rad. When ATR tracks the circular path (where the curvature is always changing), the initial position and orientation for target trajectory are [10, 0, π/2]
T; the initial position and orientation for ATR start from [7, 0, π/2]
T; and the angular velocities of both the left and right driving wheels start from 0; ASMC can adjust the output control in time, and output the angular velocities of left and right driving wheels smoothly, which makes the position and orientation error for ATR approach to 0, and ensures that ATR can never become divorced from the reference trajectory. Through experiments in the field, the results show that when ATR tracks the combination trajectory of curve and slash paths, ATR runs at velocity of 1, 3, and 4 m/s, the tracking error for ATR ranges from −0.04 to 0.04 m along the distance error in the direction of motion, and from −0.09 to 0.07 m along the lateral distance error, and the heading error ranges from −0.03 to 0.05 rad, which enables the actual ATR trajectory to follow the desired route smoothly. Thus, the adaptive sliding mode control based on DC (direct current) motor drive for ATR can achieve promising tracking performance, and satisfy the requirements of the farmland work. All results verify the effectiveness and correctness of the control method.
