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Thinning is one of the three labor-consuming sections (pruning, thinning and harvesting) in orchard management process. Chemical thinning, not only unstable but also reduces fruit safety, has been banned gradually in recent years. Pure artificial thinning, especially artificial fruit thinning, needs larger workload and higher labor cost, unsuitable seriously for the requirements of modern orchard planting. Two kinds of pear mechanical flower thinners were designed in the paper. They were three arms tractor-mounted flower thinner (TMFT) and hand-held flower thinner (HHFT), to alleviate the heavy labor pressure in the process of thinning and improve the efficiency of orchard operation. The width of TMFT was controlled by hydraulic cylinder that range from 1.2 to 1.7 m. TMFT rotation speed of thinning shaft that range from 0 to 300 r/min was controlled by electronic governor. The length of HHFT can change through adjusting the extension rod that range from 0.95 to 1.6 m. HHFT rotation speed of thinning shaft that range from 0 to 900 r/min was controlled by electronic governor too. ‘Y’ trellis ‘Cuiguan’ pear was taken as the research object in the paper. TMFT impact forces of thinning rope with different rotation speed of thinning shaft and thinning distance were measured in bench test, to find the working range of rotation speed. Field test setting 50% flower bud preserved rate (it is easier to thin flower buds than flowers) and 0.44 m/s tractor work speed, and the best rotation speed of thinning shaft was ensured: 254 r/min. Flower bud reserve rate, fruit set rate, work efficiency, fruit yield and quality of four kinds of operation methods were tested, which were TMFT combined with artificial fruit thinning, HHFT combined with artificial fruit thinning, artificial flower fruit thinning and artificial fruit thinning only. Twenty-four ‘Y’ trellis pear trees (6 a) with almost same size were selected for four operation methods. The canopies of each tree were divided into the upper middle lower three layers and five branches were selected as samples in each layer. In order to reduce the operation error, except the TMFT, the operation of each group was completed by two workers with experienced job skill. Field test show that three flower thinning methods can meet the requirement of 50% flower bud preserved rate, the coefficient of variation all less than 15%. There is no obvious difference between TMFT and artificial method in thinning quality and the stability of TMFT is the highest among test groups. Mechanical and artificial flower thinning can significantly reduce about 50% absolute fruit set rate. TMFT will damage the young fruits in a certain degree, but does not affect the yield and quality in the last. Work efficiency of TMFT was highest among flower thinning methods and 66.17% artificial fruit thinning time can be saved. TMFT has a higher requirement for pear orchard mechanization degree, suitable for large-scale mechanized pear orchard. Work efficiency of HHFT is second only to TMFT, 37.26% artificial fruit thinning time can be saved. HHFT is suitable for small and medium sized pear orchard. For fruit yield and quality, total and high quality fruit yield per tree of pure artificial fruit thinning group is higher 11.37% and 8.59% respectively than average values of three kinds of flower thinning group, but the average weight of high quality fruit and brix of sugar solids of is lower 6.58% and 1.55% respectively. The research is helpful to improve the working quality of flower thinner and provide reference for the mechanization management of pear orchard. [ABSTRACT FROM AUTHOR]

Large-scale grain drying technology has a nearly 50 years of development history in China. There are concurrent flow dryer, countercurrent dryer, cross flow dryer and mixed flow dryer, which meet the actual needs in various fields. But compared with the similar foreign products, there are many defects on our grain dryer, such as low manufacturing technology, low level of automation and high energy consumption. The co-current flow dryer has the characteristics of dry uniformity, low unit heat consumption and high productivity. But there are some defects, such as poor control of drying quality, high cost of drying and environmental pollution. These shortcomings are not conducive to the sustainable development of agricultural production and ecological environment. Therefore, from the perspectives of the structure and the process of the high temperature grain dryer, combining energy saving with conservation of grain quality is the key to the development of modern grain drying technology. Generally, the form of air supply in large-scale grain dryer is positive pressure, with easy maintenance and adjustment. The negative pressure air supply technology is only used for small cycle dryers. In this paper, the negative pressure technology in the large-scale grain drying system was applied for the first time. Negative pressure drying can effectively solve the internal control problems of the drying process based on the theory of micro pressure. Negative pressure is beneficial to collect the grain dust, create excellent production environment and realize safe production. The losses of static pressure and dynamic pressure are relatively small in the process of negative pressure drying, and this technology can reduce power consumption, and is easier to realize intelligent control of air volume and air medium parameters. In order to reduce primary energy consumption and improve corn drying process capacity, combined with grain drying characteristics in cold region, 5HFS-10 type negative pressure grain dryer was designed based on the principle of negative pressure drying. This drying technology combined the multi-stage concurrent flow and countercurrent flow, and a set of advanced structure and control system were applied in this drier. The parallel dilated fan was combined with variable diameter cornute duct, the cold air quota regulation agencies were coordinated, online work parameters were real-time collected with multi sensors, the adaptive control system was adopted, and all of these completed the intelligent quality-guaranteeing drying production of the staple food crop. In this paper the calculation of drying parameters and structure parameters was carried out providing the theory basis for the comprehensive evaluation and the design of negative pressure dryer. Production test shows that the machine’s work performance is good, its energy saving is significant, and it has good drying quality, unit mass of low cost, high degree of automation, and so on. The deviation of the moisture of discharged grain is less than ±0.5% w.b. Compared with the traditional positive pressure air supply dryer, this dryer saves the power by more than 20%, and reduces the production cost by more than 12%. The operating performance can perfectly meet the requirements of farm drying and large-scale drying technique. It provides the theoretical basis for the development of energy-saving intelligent grain dryer. [ABSTRACT FROM AUTHOR]

The middle and lower reaches of the Yangtze River are the main producing areas of winter rapeseed in China. However, due to the effects of harvesting agricultural crops, heavy soil compaction, small field, the mechanization level of rapeseed is low. The level of intelligent seeding needs to be improved. In this paper, a navigation controller for small crawler-type seeder based on immune PID was designed to solve the problem of intelligent seeding in the middle and lower reaches of the Yangtze River where the soil is sticky, the field is small. The small crawler-type rape seeder automatic navigation control system was designed. It used the small crawler-type rape seeder as the platform, and its steering system was modified by electromagnet. The high-precision BeiDou positioning module and the electronic compass was used for combined navigation to obtain the position and heading information of the crawler-type rape seeder as the input of the navigation controller. The immune PID controller was a nonlinear P controller that could adjust the proportional coefficient according to the feedback in real time. The control process was as follows. First, the plane coordinates of the start and end points of the straight path to be tracked are artificially set, and the main controller automatically calculated the distance of the target heading the start point and the end point. The weighted average algorithm was used to filter the longitude and latitude coordinates collected four times to get the current position. The controller calculated the distance deviation from the current position to the set route by the point-to-line distance formula. Taking the filtered distance deviation as an input, the target heading was calculated using the target heading correction formula distance deviation. Then, the course deviation (the deviation between the corrected target heading and the heading acquired by the electronic compass in real time) is used as an input of the immune PID controller, and the immune PID controller determines the Duty Ratio as the output u to act on the steering mechanism, achieving control of the steering of the track-type seeder. In addition, According to the characteristics of the tracked vehicle, the steering of the small crawler-type rape seeder was analyzed, and its steering model and steering angle transfer function were established. The immune PID controller was verified by Matlab simulation and experiment. Under the same parameters, the simulation showed that, compared with the conventional PID control, the immune PID control had the characteristics of fast response, small overshoot and small average tracking error. The pavement experiment showed that when the vehicle speed was 0.50 m/s, the average absolute deviation of the linear tracking of the immune PID controller was 4.2 cm, and the maximum deviation was not more than 12.0 cm. The field experiment showed that when the vehicle speed was 0.50 m/s, the average absolute deviation of the linear tracking of the immune PID controller was 5.8 cm, and the maximum deviation was not more than 15.2 cm, which was 32.6% and 18.1% higher than the conventional PID. It could better meet the requirements of the seeder navigation operation. This research provides a technical reference for the autonomous navigation of the crawler-type rape seeder. [ABSTRACT FROM AUTHOR]

In order to solve the problem of equipment adjusting in the operation of plough rotary tiller, an automatic leveling system of plough-rotary tiller is designed, which includes executive mechanism, automatic leveling control module, hydraulic system and tilt sensing module. The plough-rotary tiller is a kind of well-behaved machine on tillage and straw returning, which combines the function of plough turning and rotary tillage. It can be used to carry out multiple work processes such as plough turning, rotary tillage and burying ground straw into soil. The soil is finely ground after ploughing, and the crop stalks and stubble are directly buried in the fields to achieve the soil preparation effect. It can also reduce the number of operations of going into soil for the machine, reduce the compaction of the soil, and improve the efficiency of farming. In the process of work, one side of tractor wheel drives on the balk, the other side drives on the cultivated furrows, causing tractor to incline to walk, and then leading to a certain inclination in horizontal direction of the plough-rotary tiller connected with the tractor through the three-point suspension mechanism. However, the tilting of plough-rotary tiller will affect the flatness and depth of the plow, so it is necessary to continuously adjust the equipment to ensure the work effect. Due to the complexity of field work condition, it needs to adjust frequently on the first 2 work routes and every route caused by the unstable work of the hydraulic system in each field. It not only is time-consuming but also has not high precision, which results in poor performance and low efficiency of work. In order to solve the problem of frequent adjustment of the plough-rotary tiller during work of plough, combining the characteristics of the plough-rotary tiller, a method to determine the angle range of leveling is put forward. The plough-rotary tiller as a compound tillage machine has great quality. It will cause great burden to the hydraulic system of the tractor by automatic leveling. At the same time, the downward motion will appear more severe during the downgrading process of the plough rotary mechanism. Therefore, a set of independent hydraulic system is designed in this paper. According to the actual field work situation, the soil model is established by using EDEM (enhanced discrete element method) simulation software, and the virtual simulation of field operation is carried out. The simulation results show that the surface roughness is less than 2 cm and meets the agronomic requirements. On the basis of design and simulation, field experiments were carried out to compare the operation of manual leveling plough-rotary tiller and the operation of automatic leveling plough-rotary tiller. The content of the test includes the system performance and mechanical performance of automatic leveling. The system performance is obtained by analyzing the change of the inclination angle of the tractor. The mechanical performance is obtained by analyzing ploughing depth, its stability and surface roughness after the operation. The results show that the automatic leveling plough-rotary tiller has a marked improvement in the stability of ploughing and surface evenness after tillage compared with the manual leveling plough rotary machine. The stability coefficient of the former tillage depth is 87.31% and the latter is 84.76%. The surface roughness of the former is 1.97 cm and the latter is 2.56 cm. It can provide reference for the design of automatic leveling system for compound agricultural machinery. [ABSTRACT FROM AUTHOR]

Thinning is required in fruit tree production to ensure high quality fruit and proper fruit size, which is one of the most labor-intensive practices. Mechanical blossom thinning is an environmental friendly alternative to chemical blossom thinning. Good tree training techniques are required to get high-level blossom removal for mechanical thinning. Electric flexible thinner can realize blossom thinning by rotating flexible strings. There is a challenge in mechanical thinning due to the varying shape of tree canopy. To improve the adaptability of the electric flexible thinner on fruit tree variety, canopy shape and size, it is important to develop a profiling control system. In this paper, the structure of the actuators for profiling action of the electric flexible thinner was proposed. The flexible thinner was suspended on the rear three-point hitch of a tractor and consisted of a vertical rotating spindle attached with several segments of nylon cords in horizontal direction. The spindle was rotated by a brushless direct current motor and its spatial position could be adjusted by translational screw and profile adjusting screw. The ball screws were driven and controlled via stepper motors, which could control the offset into the trees and the angle of the thinner. With the ball screws, the thinning spindle could be stretched and tilted to conform to the height and inclination of the tree canopy. The range measuring rod could map the canopy as it passed and was placed ahead of the spindle to avoid sensor collision with rotating cords. Two pairs of ultrasonic sensors suspended on the range measuring rod could provide the angle and lateral offset sensing of the flexible thinner position by sending infrared laser pulses out and measuring the round-trip flight time to the trees. The spindle rotation speed, screw displacement and thinning angle were adjusted by the electric motors. During the blossom thinning process, the centrifugal force on the panicles of the fruit tree was used to cause rotating nylon cords to thin blossom. The intensity of thinning could be controlled by changing the spindle rotation speed, tractor speed and string arrangement and other parameters. To get the key parameters of profiling control, the geometric relationship between flexible thinner and canopy edge was analyzed. Using the modular structure, the hardware and software of profiling control system were developed. The controller performed the planning task and calculated the number of pulses for stepper motors of ball screws between the current position of the thinner and the currently measured canopy. All field tests with the electric flexible thinner were conducted at a tractor speed of 1.93 km/h. The field test results of single litchi plant illustrated the position servo control performance of two ball screws of the electric flexible thinner. The measured dynamic mean errors of the translational screw and profile adjusting screw were 0.17 and 0.07 cm respectively. To improve the performance of profiling controller, it required to move the thinner quickly without affecting thinning speed and to reduce the control latency to acceptable levels. The experimental results show that the actuators have good position adjusting accuracy and the proposed profiling control system can meet the requirements of real-time control. [ABSTRACT FROM AUTHOR]

Plug seedlings transplanting, which has comprehensive benefits including high and stable yield, climate compensation and improving land utilization, is an important part in the process of dry land crops production. At present, the crops, such as maize, sugar beet, rapeseed, cotton, tobacco and vegetables, apply dry land seedlings transplanting in China, with total planting area of nearly 50 million hm2 in 2014 which goes in advance in the world. At the same time, semi-automatic transplanting machine is the main equipment for dry land crops transplanting domestically, and the work of picking up and delivering seedlings is finished manually. It results in high-intensive labor and high producing cost. Aiming at some existing problems in China, such as low level of automation in vegetable transplanter and high rate of injuries during picking up and delivering seedlings, a system for picking up and delivering seedlings in automatic transplanter is designed in this paper. In this tester, step mechanism is used to realize the vertical and horizontal movement of plug seedlings, row type of seedlings pushing up mechanism and clamps are adopted to implement the work of pushing up and clamping plug seedlings, and seedlings catching, seedlings stirring up, seedlings delivering, seedling dropping mechanism, etc. are applied to finish the task of delivering plug seedling from bowl plate to transplant instruments. During the whole operation all actions of the system are finished through the programmable logic controller(PLC), which controls pneumatic cylinders and hydraulic motors. Theoretical analysis and MATLAB simulation have been done, and the results show optimum working pressures of 2 drive cylinders which drive seedlings pushing up mechanism and control the opening-closing of clamps’ clamping piece are 0.2-0.4 and 0.1-0.3 MPa respectively for pepper seedlings. In order to verify optimization results, single-factor experiment is carried out respectively. The results show that the optimal working pressure of the drive cylinder driving seedlings pushing up mechanism is 0.4 MPa and that of the drive cylinder controlling the opening-closing of clamps’ clamping piece is 0.25 MPa. The functional relationship among 3 parameters which are the frequency of picking up seedlings, the speed of delivering seedlings, and the forward speed of transplanting machine are obtained through theoretical analysis. Besides, levels of these 3 factors are optimized, the 4 groups of best combinations of the factors are achieved, and orthogonal experiment is conducted, in which experimental indices are missing ratio of seedling transplanting, seedling repeated planting ratio, seedling lodging ratio, and seedling damage ratio. Using an experimental automatic vegetable high-speed transplanting machine cooperatively developed by College of Mechanical Transportation of Xinjiang Agriculture University, the experiment is conducted in the farm of Regiment 22, Division 2 of Xinjiang construction Corps in Hejing County, Xinjiang. Pepper seedlings which come from the farm of Toudun river, Urumqi, Xinjiang serve as the test sample. The age of seedlings is 52 days, and their plant height is 142 mm. Through analysis on the experiment result, it reflects that the system achieves the best quality of seedlings picking up and delivering when the frequency of picking up seedlings is 7 times/min, the speed of delivering seedlings is 42 m/min, and the forward speed of transplanting machine is 20 m/min. [ABSTRACT FROM AUTHOR]