No abstract

It is a fundamental work to realize intelligent fruit-picking that mature fruits are distinguished from complicated backgrounds and determined their three-dimensional location. Various methods for fruit identification can be found from the literatures. However, surprisingly little attention has been paid to image segmentation of multi-fruits which growth states are separated, connected, overlapped and partially covered by branches and leaves of plant under the natural illumination condition. In this paper we present an automatic segmentation method that comprises of three main steps. Firstly, Red and Green component image are extracted from RGB color image, and Green component subtracted from Red component gives RG of chromatic aberration gray-level image. Gray-level value between objects and background has obviously difference in RG image. By the feature, Ostu's threshold method is applied to do adaptive RG image segmentation. And then, marker-controlled watershed segmentation based on morphological grayscale reconstruction is applied into Red component image to search boundary of connected or overlapped tomatoes. Finally, intersection operation is done by operation results of above two steps to get binary image of final segmentation. The tests show that the automatic segmentation method has satisfactory effect upon multi-tomatoes image of various growth states under the natural illumination condition. Meanwhile, it has very robust for different maturity of multi-tomatoes image.

The solidification and molding of straw has been an effective method for comprehensive utilization of straw resources. However, the existing die-roll extrusion-type straw briquetting machine has challenges, such as the easy blockage of ring die holes and the unstable quality of the briquette. In this paper, the influence of four factors, including moisture content of straw, molding temperature, clearance between die and roller, and spindle speed on the quality of the briquette were studied. The regression model of the relaxed density and impact resistance of the briquette were established to obtain the optimal values of these factors to provide the best parameters for producing straw briquette. The results indicate that under the experimental conditions of moisture content 22.335%, temperature 85.127 °C, clearance between die and roller 3.099 mm, and spindle speed 172.712 r/min, the maximum relaxed density and impact resistance of the briquette were 1.144 g/cm3 and 74.76%, respectively. The performance of the briquette already meets the requirements for combustion, transportation, and storage.

The briquetting technology of rice straw could increase the bulk density of the straw, reduce transportation and storage costs, and improve resource utilization. This paper analyzed the working principle of the air-conveying integrated device in briquetting machines. High-speed photography technology was used to track and record the movement process of crushed straw material in the air-conveying cylinder area. It was compared with the simulation results of the average velocity of crushed straw material to verify the reliability of the simulation. The results showed that the flow of straw scraps in the straw-shredding and air-conveying integrated device was relatively stable when the impeller speed was 630 r/min, the number of blades was three, the blades were tilted back 15°, and the radius of curvature of the air-conveying tube elbow was 700 mm. At the same time, the speed distribution was uniform, and the highest throwing speed reached 4.5 m/s to 4.8 m/s. After optimization, the average increase rate of briquette density was 2.61% and the average increase rate of briquette productivity was 2.52%. The fluid movement law of the straw-shredding and air-conveying integrated device studied in this paper could be used to optimize the air-conveying device, improve the efficiency of straw briquetting and the utilization rate of straw resources.

Aiming at the existing single-motor agricultural tractors, which often have a mismatch between power and working conditions and a poor operation effect under different tillage modes, this paper designs a torque allocation strategy for agricultural electric tractors under different tillage modes. Firstly, the torque is divided into basic and compensating, and a calculation model is established. Then, the Particle Swarm Optimization algorithm is used to find the optimal demand torque position, and fuzzy control rules allocate the motor torque in combination with the battery SOC. Finally, the strategy’s effectiveness in different tillage modes is verified by MATLAB/Simulink simulation and bench test. The test results show that the strategy can distribute the motor torque stably according to the load torque change and pedal opening under three PTO transitions and the plowing and rotary tillage modes. The main and speed control motors respond in about 3 s with good real-time performance. The drive wheel torque can reach 1600 N-m during plowing and rotating operation. The PTO torque can reach 60 N-m during the rotating process. The maximum torque of the output shaft can reach 150 N-m with good plowing performance. During all operations, the SOC of the battery shows a steady linear decrease, and the battery discharge has stability.