Evaluation of the technical capacity of artisans to fabricate the animal-powered direct seeder super-eco in Sénégal.

This study focused on the ability of local Senegalese artisans to fabricate the animal-powered no-till (NT) direct seeder Super-Eco to reduce the expensive import of seeders. Technical specifications and design of the animal-powered direct seeder Super-Eco were first given to 90 heads of artisanal workshops in three regions of the Southern Peanut Basin for them to reproduce the machine. Detailed information on their workshop equipment was collected in advance. A principal component analysis (PCA) was then used to classify artisan workshops. The results showed that Class 3 was very well equipped and was able to fabricate the direct seeder. It was followed by Class 2 which was fairly well equipped, but was only able to develop 90% of the seeder parts. Because of a low level of equipment, the third class of artisans was only capable of fabricating very few pieces of the seeder. Artisans from Class 3 were able to fully construct the animal-powered direct seeder. However, it was noted that the other classes of artisans were able to reproduce some parts of the animal-powered direct seeder Super-Eco but they could not make the seeder box with its nested seed metering device due to their low level of equipment. They instead buy it from the Sahelian Industrial Company of Mechanics, Agricultural Materials and Representations or from traders. The need to evaluate the performance of the seeders developed by local artisans is also noted.

PARAMETER OPTIMIZATION AND EXPERIMENT OF SLIDER-HOLE-WHEEL SEED-METERING DEVICE BASED ON DISCRETE ELEMENT METHOD

To improve the adaptability and precision of the slider-hole-wheel seed-metering device to meet the requirements of precision sowing, the single factor simulation experiments and the three factors three levels of orthogonal simulation experiments were carried out based on the discrete element method. The rotation speed of the seeding shaft, the shape of the hole, and the depth of the hole were set as experiment factors. The results of simulation experiments showed that the qualified rate was the highest when the rotation speed of the seeding shaft was 30 r/min, the shape of the hole was oval, and the depth of the hole was 9 mm. The qualified rate, replay rate, and miss-seeding rate were 89.09 %, 3.64 %, and 7.27 %，respectively. The hybrid rice seeds of Zhongnong 2008, Chuangliangyou 4418, and Gangyou 898 were chosen as the materials for the bench and field seeding performance tests to verify the reliability of the simulation results. The test results showed that the qualified rate of Zhongnong 2008, Chuangliangyou 4418, and Gangyou 898 seed in bench tests were 85.07 %, 85.20 %, and 82.13 %, and the qualified rate of Zhongnong 2008, Chuangliangyou 4418, and Gangyou 898 seed in field tests were 82.13 %, 82.27 %, and 80.53 %. The seeding performance with the three kinds of rice seeds could meet the agronomic requirements for precision sowing of hybrid rice. The paper provided the basis for the structure optimization and seeding performance improvement of the slider-hole-wheel seed-metering device.

EXPERIMENTAL STUDY ON AIR FLOW FIELD CHARACTERISTICS OF SUCTION METERING DEVICE

The vacuum seed metering device absorbs seeds by using the negative pressure generated by vacuum air flow. Therefore, it is of great significance to study the variation law of pyrolysis gas flow field to improve its seed metering performance. In this paper, the common disc and composite disc were selected as the research objects and tested on the indoor test-bed. The negative pressure was measured by U-type barometer, and the effects of fan speed, suction hole size, seed hole structure and air chamber thickness on the air flow field were studied. Firstly, the influence of fan rotation frequency on vacuum chamber negative pressure is studied, and the variation law of negative pressure in vacuum chamber and fan port of common disc and composite disc under the same frequency is compared. Secondly, the suction holes in the vacuum chamber were numbered, the negative pressure distribution of the suction holes was measured, and the influence of the number and diameter of the suction holes on the negative pressure of the vacuum chamber was studied. Finally, the negative pressure was measured at the distance of 0 to 10 mm from the suction hole to study the effect of seed hole structure on the air flow field. Moreover, increase the additional thickness of the vacuum chamber from 0 to 40 mm to study the influence of the chamber thickness on the distribution of the gas flow field. This paper makes a comprehensive experimental analysis on the influencing factors of air flow field of air suction seed metering device, necessary for future design of air suction seed metering device.

EFFECT OF SEED FILLING AND RELEASING ANGLES ON THE PERFORMANCE OF COMPOUND VACUUM SEED METERING DEVICE

In this paper, taking compound air-suction seed metering device as the subject, the effect rule of seed filling angle and seed releasing angle on the performance of seed filling and seed metering is studied. An indoor test was conducted with a JPS-12 metering test bench and a high-speed camera system. The starting and ending angles of the air chamber were changed by adjusting the regulating plate, that is, the angles of seed filling and seed releasing, and the filling and seed metering performance was taken as evaluation indexes. The test results show that: the seed filling angle has significant effect on the seed filling effect, and the miss fill index decreases with the increase of the quality of fill index. When the seed filling angle exceeds 50°, they will stabilize gradually ending at the multiple fill index of 0%. The negative pressure and operating speed are interactive and have a significant effect on filling performance. The seed releasing angle has significant effect on the metering performance. With the increase of the angle, the quality of feed index increases firstly and then decreases. The multiple index and miss index are opposite to the quality of feed index which is the max at the seed releasing angle of 39.5°. The negative pressure and forward speed are interactive and have a significant effect on metering performance. The quality of feed index under the same condition is lower than that of fill index.

WORKSPACE ANALYSIS OF A FLAME INTRA-ROW WEEDING ROBOT IN VEGETABLE FIELD AND NUMERICAL SIMULATION OF PROPANE COMBUSTION

In order to improve the seed filling performance of mechanical hole type seed metering device with high speed, a vertical disc metering device was designed with seed agitator to improve the seed filling probability. Discrete element simulation method and physical prototype bench tests were used to simulate and analyse the seed metering process. The structure parameters of the seed agitators were optimized by the quadratic orthogonal rotation central composite design test. The results showed that: 1) the addition of seed agitator had a significant influence on the MIS (miss index), among which the concave type had the lowest MIS, and it was the highest without agitator; 2) for concave type agitator, the optimal value of depth and angle were 3.1 mm and 60.5°, respectively; 3) the physical prototype tests showed that the QFI (quality of feed index) was more than 95% under the speed of 2-10 km/h, and the MIS was less than 1%, which meets the requirements of precision sowing.

Design and Simulation of a Garlic Seed Metering Mechanism

According to the agronomic requirements of garlic sowing, the garlic morphology is studied and a garlic seed metering mechanism with excellent seeding performance is designed. Based on this design, a new garlic seeding machine with an adjustable-size seeding device is developed to realize efficient single-seed metering and seeding of different varieties of garlic. Further, the design scheme of the garlic seeder prototype is established, with the key components of the garlic seeding being designed on the basis of the garlic seeding mechanism. To achieve garlic single-seed metering for different varieties of garlic, the optimal adjustment size of the garlic seed metering device is determined through discrete element simulation analysis. A field experiment confirms the effectiveness of applying the proposed garlic planter to field sowing in terms of the metrics of missing seed and multiple seed rates. The results of the discrete element simulation test reveal that an adjustment size of 40 mm yields the best single-seed metering performance. At an operating speed of 15–35 rpm, the metering device can achieve more than an 80% qualification rate of single-seed metering, with a unit speed of 0.628–1.465 m/s. Thus, the developed garlic seeding device meets the requirements of precision sowing in China and can effectively realize the mechanized planting of garlic.

Theoretical and Experimental Studies on Air-suction Roller-type Precision Seed-Metering Device

The seed-metering device is the key component of a precision seeder. The methods to improve the seed suction and dropping efficiency of air suction drum precision seed metering device were discussed Establishing the force and equation of motion for sucking, carrying and dropping stages, the effect of the seeding parameters on the effect of sucking and seeding is analyzed. Then, the single factor and orthogonal test are carried out on the sucking pressure, the carrying pressure, the rotation rate and the dropping pressure as the experimental factors for the optimization analysis. And the optimum experimental parameters and the predicted values of each test index are obtained. That is, when the seeding pressure of -2.87kPa, the seeding pressure of -1.91kPa, the drum rotation rate of 18.72 r min-1 and the dropping pressure of 1.74kPa, the best effect that the single rate is 93.8%.

DESIGN AND PERFORMANCE TEST OF DIRECT SEED METERING DEVICE FOR RICE HILL

In order to meet the requirements of rice field precision direct seeding in rows and hills, a spiral grooved seed metering device for rice field precision direct seeding in hills is designed. The Matlab software is used to study the movement trajectory of rice buds in the spiral groove during the seeding process. Based on the quadratic regression-orthogonal rotation combination design, and taking the working speed of the seeding wheel, the spiral groove length and the helix angle of the spiral groove as the test factors, as well as the qualified rate of hill diameters, the qualified rate of hill grains and the miss-seeding rate as the indicators, the seed metering performance is tested by JPS-12 metering device test bench. The test data are analyzed by using Design-Expert 6.0.10 software to obtain a mathematical model between the factors and indicators. The test results show that when the spiral groove rise angle is 71.0°, the spiral groove length is 10.8mm, and the working speed of the metering wheel is 23.2r/min, the qualified rate of hill diameter, qualified rate of hill grains and miss-seeding rate are 91.06%, 94.64% and 3.64% respectively. The seeding performance meets the agronomic requirements of rice field seeding.

DESIGN AND TEST OF NEGATIVE PRESSURE CHAMBER ROTARY BUCKWHEAT SEED METERING DEVICE

A negative pressure chamber rotary precision seed metering device was designed to achieve the buckwheat precision sowing goal, solving the problems of traditional negative pressure chamber poor sealing and air suction seed metering device high power consumption. The planting plate of the device was fixedly connected with the shell of the air chamber forming a negative pressure chamber, which rotates around an axis. A planting plate suitable for buckwheat seed metering was designed. Single factor test and response surface test were carried out on the seed metering device. Results showed that the buckwheat precision seed metering achieved best performance when the negative pressure, suction hole diameter and rotation speed was 2.4 kPa, 2.0 mm and 25 r/min respectively. The qualified index, multiples index and miss-seeding index were respectively 88.32%, 7.35%, and 4.33%, which met the technical requirements of buckwheat precision sowing. The results of the study provided references for the design and application of buckwheat precision seed metering device.