Research Article, J Plant Physiol Pathol Vol: 4 Issue: 2
Development and Prototype Experiment of Environmental Self-Propelled and Orderly Harvester for Artemisia selengensis Turcz
|Shi Yinyan, Zhang Yongnian and Wang Xiaochan*
|Department of Agricultural Biological Environment & Energy Engineering, College of Engineering, Nanjing Agricultural University, China
|Corresponding author : Wang Xiaochang
Agricultural Biological Environment Simulation and Control, Nanjing Agricultural University, China
|Received: January 05, 2015 Accepted: May 25, 2016 Published: May 30, 2016
|Citation: Yinyan S, Yongnian Z, Xiaochan W (2016) Development and Prototype Experiment of Environmental Self-Propelled and Orderly Harvester for Artemisia selengensis Turcz. J Plant Physiol Pathol 4:2. doi:10.4172/2329-955X.1000150
We developed an environmental and self-propelled harvester with the aim of overcoming the problem of low efficiency, high cost, and complex processing in Artemisia selengensis mechanization harvesting; the developed harvester can complete cutting, conveying, and collecting for selengensis harvesting in an orderly manner. The basic structure and working principle of the machine were determined, including the structure design and parameter analysis of the key components such as the clamping conveyor, steering device, and cutting device. Through theoretical research and a prototype test, we confirmed the machine battery capacity to be 48 V/100 Ah, the conveyor angle θ to be 30°, the adjustable range of the stubble height to be 100-400 mm and the drive motor model, etc. The field experiments indicated that the orderly harvester structure was reasonably designed, easily operated, and helped realize orderly harvesting for selengensis. The mean working velocity, the forward speed, the feeding rate, and the efficiency of the machine can be up to 0.84 m/s, 6 m/s, 0.62 kg/s, and 0.2 hm2/h respectively. The swath quality meets the industry standards and the subsequent production requirements, which contriAgricultural mechanization developmentbutes to facility agricultural mechanization development.
Keywords: Cutting; Collecting; Clamping convey; Theoretical research;Prototype test
|Cutting; Collecting; Clamping convey; Theoretical research; Prototype test
|Artemisia selengensis Turcz, which is native to Asia, is rich in a variety of essential mineral elements and vitamins and has high medicinal value. In addition, according to the literature, selengensis has antioxidants, helps decrease blood pressure, protect the liver, and is loved by many people [1-4]. Selengensis prefers a sunny environment for growth, a wide temperature range, and no obvious dormant and rare diseases and insect pests; selengensis is a pollution-free green food, one of the main wild and special vegetables [5-8]. Selengensis in recent years has become a nutrient-rich, fresh vegetable, planted in the wild as well as artificially grown; its cultivation area is thus increasing. Ba-gua continent, in Nanjing city, Jiangsu province, known as China’s “first township” for selengensis, has a cultivation area of 40000 acres and it annual output is above 50 million kilograms, helping to develop the local economy [9,10]. However, because of the complexity in selengensis harvesting, there are some shortcomings with the planting area such as difficult in laying, high cost, low efficiency, labor shortages, and low level of mechanization; these shortcomings hamper the sustainable development of the selengensis industry.
|Therefore, it is necessary to develop an efficient and practical orderly harvester, for realizing efficient selengensis mechanized harvesting. A small and efficient environmental self-propelled orderly harvester machine for selengensis Turcz was developed in this study. The developed harvester has reasonable structure, high efficiency, low labor intensity, and economic cost. Moreover, it is environmentally friendly with no pollution, achieves cutting, conveying, and collecting for selengensis harvesting in an orderly manner. It helps overcome the shortcomings of existing orderly harvesters, adapts to the mechanization harvesting of protected agriculture production, and plays an important part in the development of the facility vegetable industry in China.
Materials and Methods
|Design requirements and machine structure
|Because of the manner in which selengensis grows, the selengensis stem and root must be cut separated in an orderly harvesting process, after which it must be conveyed via an orderly steering mechanism through the clamping conveyer. The crops must not avoid being clamped or slackened, nor must they be held too tight to prevent damage. The laid selengensis is then conveyed and collected in baskets by the conveyor belt.
|The structure of the developed environmental self-propelled and orderly harvester for Artemisia selengensis Turcz is composed of a frame, cutting device, clamping transmission device, horizontal transmission device, steering device, collecting device, walking system, electric control system, batteries, etc., which is shown in Figure 1.
|Figure 1: Structure diagram of orderly harvester for Artemisia selengensis.
|The developed self-propelled harvester is a smart orderly harvester, which is purely electrically driven, efficient, and environmentally friendly. The stubble height of the harvester can be adjusted, and the harvester has the function of automatic copying. The harvest width is 1m, which is suitable for protected agriculture. The working bench fixed on the self-propelled chassis, change the angle between the bench and ground by adjusting the linear actuator, and the height from the ground of the cutting device is then adjusted, so as to adapt to different crop stubble heights. During the harvesting process, the clamping transmission device grips the selengensis and conveys it tilted upward to the cutting device. When conveying to the steering device, the crop root stumbles, and the selengensis is laid on a horizontal conveying device backward; the conveying belt transports selengensis in an orderly manner to a collection basket in the side. The entire harvesting process meets the requirements of cutting, conveying, and collecting in an orderly manner. This harvester helps realize mechanized harvesting for Artemisia Selengensis.
|Main structure and function of key components
|Selection of power type: The core aspect in agricultural machinery is the selection of driving force, so it must form the equipment with clean energy as power source to achieve an environmental, efficient, and convenient way of production. Battery power was adopted as the force to drive the entire machine. The use of a battery prevents environmental pollution, which would otherwise be a problem with the use of a diesel and gasoline engine; moreover, the use of battery power would facilitate the regrowth of selengensis crops. The selected power source is suitable for greenhouses scale production, improves the working environment, reduces the labor intensity, enhances the working efficiency, and promotes facility agricultural mechanized production.
|Motor power and battery capacity are crucial factors for varying the maneuver performance of the machine, providing continuous mileage, and realizing a long battery life. As the prototype is still in the experimental stage and considering the economic costs, lead-acid batteries were used. Taking the moving motor as an example, we calculate the motor power and select the motor model [11-14]. In moving process, the driving force the machine generated to the ground is equal to counter-force the ground, air, etc., to the harvester, but the direction is opposite. For ease in calculation, we assume that the machine moves on a flat road. The driving force is calculated as follows:
|Where Ft is the driving force, Fw is the air friction, and Ff is the rolling resistance.
|According to the principle of aerodynamics:
|Where A is the windward area and Cv is the air resistance coefficient. Considering the quality of the entire machine and the slow speed of the harvester, the air resistance can be ignored in comparison to the rolling resistance.
|Accounting for the differences in driving conditions, operating state, and assumptions in an actual harvesting process, ensuring the necessary maneuvering performance, and consulting the similar specifications of motor, the 48V/1000W brushless dc motor was selected. For 3 h of continuous operation of the harvester, we calculate the total power consumption for cutting, walking, and conveying to select the effective capacity of the battery.
|Owing to the low price of lead-acid batteries and the light weight, a capacity of 48V/100Ah lead-acid battery was selected, which meets all the design requirements.
|Design of cutting device: Accounting for the machine demands of the developed environmental self-propelled orderly harvester as well as the physical characteristics of the harvested crops, a double moving-blade and reciprocating cutting device was chosen; this device has a high reciprocating frequency, well balanced performance, quick working speed, and high working efficiency. It is composed of upper and lower blades and an offset-type coaxial dual symmetric crank-conrod mechanism. The dynamic blade stroke S is 20 mm, by adjusting the screw to ensure a blade clearance of § ≤ 0.5 mm. The cutting power is output by the motor, through the belt-drive driving the crank shaft to rotate, where the eccentric direction of the two offset cranks is 180°; the two cranks drive the two blades in a reciprocating motion, which ensures that the two blades are always opposite to each other at any moment, completing the cutting process.
|According to the theory of agricultural machinery design, the cutting angle α is a key structure parameter (Figure 2); it affects the cutting resistance, as well as determines whether crop stalks can be clamped to ensure reliable cutting [15,16]. The sliding cutting speed formula is as follows:
|Figure 2: Structure and parameter diagram of cutting device.
|Where V1 is the sliding cutting speed and V is the blade velocity. When the cutting angle α increases over a reliable range, the blade sliding cutting speed V1 relative to the crop stalks increases, with the cutting resistance reduced. However, if the cutting angle α overshoots, stems will slide outward along the edge line when cutting, preventing the realization of reliable cutting. Therefore, on the premise of gripping the selengensis stalks, a larger cutting angle α should be chosen. We consider the following parameters to ensure reliable cutting quality: cutting angle α=30°, blade width c=28 mm, d=5 mm, and blade height h=20 mm.
|By substituting the known parameters, the crank speed was obtained, n=638 r·min-1, reversely; these parameters were combined with the crank eccentricity, the transmission ratio of the cutting device, and transmission efficiency, to attain a motor speed of 2000 r·min-1. Therefore, we chose a motor rated voltage of 48 V, a rated power of 200 W, a rated speed of 2000 rpm, and a rated torque of 1 N· m.
|Design of clamping transmission device: A double belt was adopted in the clamping transmission device, which mainly consists of a synchronous belt transmission and worm gearing (Figure 3), the worm-gear coaxial with active belt wheel, so that making the belt into the working state, and the conveyor belt clamping crop stalks cooperatively.
|Figure 3: Structure diagram of transmission device.
|The conveyor speed of the clamping transmission device is closely related to the machine walking speed; in addition, the velocity and direction of the touch point determine the status of the gripping delivery for crop stalks [17-19]. Under harvesting operations, and at the instant of conveyor belt clamping the crop stalks, the clamping velocity is as follows:
|Where K is the velocity ratio (ratio between the relative velocity of the conveyor and walking velocity) of the conveyor belt. During operation, the clamping transmission device moves with the machine moving forward, so the movement of crops is the synthetic movement of the conveyor belt and forward movement of the machine. The kinematic analysis for selengensis stalks is shown in Figure 4, in order to ensure the crops were gripped erectly, the synthesis velocity direction should be erect, meeting the condition given by the following equation:
|Figure 4: Velocity analysis of transmission belt.
|Where vm is the walking velocity, vt is the relative velocity of conveyor, and vd is the absolute velocity of the conveyor.
|According to the motion diagram, and combining the sine theorem, we obtain the following [20-22].
|Where θ is the angle between the conveyor belt and the horizontal plane, β is the angle between the synthesis of the movement direction and the conveyor belt, and K is the velocity ratio. When K < 1 (vt < vm), the direction of absolute velocity vd tends to the direction of machine walking, which is against transporting crop stalks reliably; therefore, the following condition must be met: K > 1. To ensure the harvester productivity and stability, the angle β should be in the range 10°-20°.
|On the basis of above kinematic and dynamic analyses, and combined with the reference of similar agricultural harvest machines, the brushless dc motor was chosen. This motor has a rated voltage of 48 V, rated power of 300 W, rated speed of 2000 rpm, and rated torque of 1.5 N· m. Moreover, a synchronous belt transmission was selected. The belt width B=50mm, which is equal to the diameter of two pulleys, the pitch diameter d=140 mm, the transmission ratio i=1, and the initial axial center distance a=1050 mm.
|Design of steering device: The bottom of the crop stalks conveyed by the transmission belt was stumbled by the steering device, and then disaffiliated from the belt clamping, and realized reversing from the erect state to lie low in horizontal, and finally it was conveyed to the collection device in one side. Because the harvest width of the designed orderly harvester is 1 m, a steering rod length L of 1 m is appropriate.
|Stalks steering smoothly and avoiding clutter and blocking was the basic requirement for the steering mechanism. When the selengensis stalks touch the steering rod, imaging the contact is completely inelastic . The bottom of the stalk is static relative to steering rod, and there must be a counterclockwise torque in the upside of the stem mass -center to make crop stalk steering; this torque is generated by the transmission force of the conveyor belt to crops. The mechanical analysis is shown in Figure 5 (assuming the machine moving towards the right).
|Figure 5: Mechanical analysis diagram of stalk turning.
|Combined with the mechanical analysis diagram, the one condition for steering smoothly when belt clamping crops exists is a counterclockwise overturn torque:
|where θ is the angle between the normal of the transmission force and the horizontal, a is the distance from the bottom to the mass -center of crops, G is the gravity of crops, N1 is the supporting force of the conveyor belt to thes crops, f1 is the friction force of the conveyor belt to the crops, N2 is the transmission force of the conveyor belt to the crops, and f2 is the friction force of the steering rod to the crops.
|It is not difficult to understand via comprehensive analysis that the angle between the transmission force and horizontal direction is the main factor influencing the selengensis stalks steering smoothly. This angle is the conveying angle θ, which was previously selected, and it should conform to the requirements of turning smoothly.
|Design of other structural devices: A horizontal transmission device is designed to transport crops that lie on the belt to collecting baskets on one side; the brushless dc motor provides transmission power for it. The device for adjusting stubble height, namely the device for adjusting the angle is composed of two electrical linear actuators installed symmetrically; the operator can adjust the height of the cutting device to the ground by changing the stroke of the electrical linear actuators. A raking device makes the crops harvested for three rows in a harvest breadth, and the claws cooperate with two. A lifter device provides auxiliary support for crops in the process of gripping delivery, which avoids the harvested selengensis being cluttered and unordered when steering. A series of synchronous belt wheels form the supporting and tension device, which can support the clamping conveyer belt; belt tension adjustment is realized by changing the diameter of the wheels, so as to ensure the reliable conveyance of crops.
|Results of prototype and field experiment: Combining the structure theory analysis of key components for the designed selfpropelled and orderly harvester, Pro/e software is used to establish the three-dimensional model of the harvester. The prototype shown in Figure 6 is trial -produced in Yangzhou city, Jiangsu province, northern latitude 32°17′51″~32°48′00″ and east longitude 119°27′03″~119°54′23”. Some minor parts were not trial-produced, because this machine is the first that is trial-manufactured. Field experiments were carried out in the selengensis planting base in Nanjing city, Jiangsu province, northern latitude 31°14′~32°37′ and east longitude 118°22′~119°14′, in May 2015. The selengensis seed breed is big-ye-qing, the ripe plant height is up to 80 cm, the diameter is 0.64 cm, the leaf length is 15.6 cm, the width is 15 cm, the planting spacing is 20 cm, and the plant distance is 10 cm.
|Figure 6: The prototype of the developed orderly harvester for Artemisia selengensis.
|According to the design and calculation of power consumption under each working condition, the agronomic requirements of the field experiments we completed, and some reference to related technical parameters of the similar type, the main technical indicators of the developed harvester we acquired are as shown in Table 1.
|Table 1: Main technical indicators of orderly harvester for Artemisia selengensis.
|The experimental results showed that the following 1. All equipment of the designed harvester machine operated well, and the selected battery capacity was sufficient for providing power. 2. It is cutting strongly, crop stalks could be cutted off effectively, and the stubble height was adjustable. 3. The clamping conveyor speed was appropriate and the crops turned smoothly; the clamping force was moderate that there was no serious loosening and falling occurred. 4. The harvesting process was steady and orderly, and met the practical production requirements of orderly harvesting for selengensis, reduced the labor intensity, improved the production efficiency, lowered the operation cost, and promoted the mechanization of the selengensis industry.
|A small, efficient, environmental, and self-propelled orderly harvester machine for selengensis was developed; this harvester can help achieve the mechanized production of selengensis, improve work efficiency, lower economic costs, and reduce labor intensity.
|The driving force of the designed orderly harvester was pure battery power, which has advantages of energy conservation, environmental protection, simple structure, convenient operation, smooth operation, and stable performance. The battery capacity is 48 V/100 Ah, the stubble height adjustment range is 100- 400 mm, and the clamping conveying angle θ is 30°. The test results showed that the mean working velocity, the forward speed, the feeding rate, and the efficiency of the machine can be up to 0.84 m/s, 6 m/s, 0.62 kg/s, and 0.2 hm2/h respectively.
|The developed harvester met the requirements of cutting, conveying, and collecting in an orderly manner for selengensis harvesting; it provided a reference to design a harvesting machine for leafy stems vegetable, and played an important part in the mechanization development of protected agriculture. Because selengensis is a seasonal crop and the prototype needs debugging, the prototype field test was not conducted over a large area. Some key data will be acquired by thoroughly researching henceforth.
|The authors acknowledge the financial support provided by the Jiangsu Province Agricultural Machinery SANXIN Project (Project No: NJ2014-08). The authors would like to thank teachers and tutors technical support. We also appreciate the assistance provided by brothers and sisters during the tests, and we would like to thank Editage for English language editing. The editor and anonymous reviewers for providing helpful suggestions to improve the quality of the present paper, to which we are grateful.