Design and development of battery-operated vertical conveyor reaper

Introduction

Agriculture is the primary source of food and is the sole occupation for a vast population in India. It ensures food security and meets the dietary needs of a population expected to reach 1.7 billion by 2050. Agriculture is vital to India's economy, engaging 54.6% of the work force and accounting for 18.6% of India's GVA in 2021-22 (Anonymous, 2021). India is one of the largest food grain producers globally, supported by a diverse agricultural sector and favorable climate. Major food grains include rice, wheat, maize, millets (sorghum and pearl millet), and pulses (chickpeas, lentils, and beans). Rice and wheat account for about 30% of global calorie intake, making them essential for billions worldwide. These staples have been cultivated since ancient times and are crucial in many diets. Rice is primarily grown in Asia, Africa, and Latin America, while wheat is predominantly grown in North America, Southern Europe, and Australia. Wheat's adaptability to different climates makes it the most versatile cereal grain, whereas rice is the chief and cheapest carbohydrate source in many developing nations. Global consumption of rice and wheat is rising due to population growth, necessitating increased production and technological advancements. India holds the second position in rice production only after China. India is also the second largest producer of wheat with a share of around 14.14% of the world's total production in 2020.

India is also inching towards self-reliance in Pulse production. The production of food grains in the country is estimated at 329.68 million tonnes in 2022-23, which is higher by 1.4 MT than the production of food grains during 2021-22. In which, total production of rice and in the country was 135.29 MT and 110.84 MT in 2022-23 respectively. Total food grain production in Chhattisgarh was 11 MT, in which production of rice and wheat was 105 MT 0.5 MT respectively during 2022-23 (Anonymous, 2022). India's soil is remarkably productive; with an average land holding of 1.08 hectares, it sustains a population of 1.3 billion. Small and marginal land holdings (< 2.0 ha) make up 86% of total operational holdings and cover 47% of the operated area (Anonymous, 2018a). The share of farm power from draught animals is declining, and agricultural power correlates directly with farm yield. In 2020-21, average farm power availability was 2.76 kW/ha. To meet the growing food grain demand, this must increase to 4.0 kW/ha by 2030 (Tiwari et al., 2019) [2] . The availability and prudent use of farm power by farmers has a significant impact on the productivity of agricultural fields. Serious issues facing Indian agriculture include a lack of labour for agricultural work, both during peak working seasons and during off-peak hours. The primary causes of this include the rise in higher-paying non-farm employment possibilities, labour force migration to urban areas, and the poor social standing of agricultural laborers. The share of workforce employed in the agriculture sector has declined from 70% in 1951 to 42.3% in 2019 and this will further reduce to 25.7% by 2050 (Anonymous, 2018b). Lack of workforce availability and pressing need for improving crop productivity calls for a strong focus on increasing mechanization in agriculture. A substantial increase is found in agriculture mechanization in India. However, the level of farm mechanization is just about 40-45% compared to other countries such as US (95%), Brazil (75%) and China (57%) (Anonymous, 2019). Agricultural mechanization is vital for enhancing food grain production by increasing efficiency and productivity. Mechanized farming methods, such as tractors, harvesters, and irrigation systems, reduce labour-intensive tasks, improve timeliness, and enhance overall farm management. This allows farmers to prepare land, sow seeds, apply fertilizers, control pests, and harvest crops more effectively, leading to higher yields, reduced post-harvest losses, and improved profitability. Timely harvesting, which involves cutting and gathering crops at the proper ripeness, is crucial to minimize losses and ensure better crop quality. Labour shortages during the harvest season can significantly impact farmers, making mechanical methods essential to ensure timely and efficient harvesting. Manual harvesting, using sickles, is labour-intensive and timeconsuming. For example, harvesting paddy and wheat manually requires about 25% of the total labour for these crops, taking approximately 158 to 160 man-hours (Tripathi et al., 2018) [3] . Cutting and bundling these crops can take 185-340 man-h/ha (Michael and Ojha, 1987) [4] , with harvesting alone accounting for a substantial portion of labour needs (Sarker, 2000) [5] . Rapid industrialization and urban migration have made labour increasingly scarce and costly, with the farm workforce projected to decline significantly by 2050 (Tiwari et al., 2019) [2] . Mechanization is the only viable solution to address this workforce shortage, ensuring timely operations and improved farm profitability. Mechanical harvesting utilizes power from IC engines and can be categorized into self-propelled and tractor/power tiller-mounted machines. Self-propelled machines have permanently attached engines, whereas mounted machines can be connected to tractors or power tillers as needed. Although versatile, mounting and detaching is time-consuming. Self-propelled reapers are increasingly used in developing countries, while combine harvesters are common in developed nations. Chhattisgarh is an agrarian state with 70% of its population involved in agriculture. Of the 41.10 lakh farmers, about 82% are small and marginal (Anonymous, 2018b). In Chhattisgarh, there are 4 power reapers and 0.09 combines per 1000 hectares, compared to the national average of 10 reapers and 0.2 combines per 1000 hectares (Singh and Singh, 2019). Combine harvesters and self-propelled reapers are efficient but expensive, posing challenges for small and marginal farmers in India. Custom hiring is an alternative but problematic for small, fragmented lands. Tractor/power tiller-operated reapers have high initial and running costs and contribute to environmental pollution. Therefore, mechanical harvesters like power tiller operated, tractor operated, self-propelled reapers and combine harvesters are not getting popularity among small and marginal farmers because of its high initial and operating cost which makes them unaffordable. Also, rising of fuel prices day by day, increases the cost of harvesting. Further, non-availability of these machines on custom hiring for small and marginal farmers, force to go for manual harvesting. Manual harvesting by sickle is laborious, costly and time consuming. The efficiency of manual harvesting using sickle is considerably low. It requires about 158-160-man h/ha to harvest paddy and wheat (Tripathi et al., 2018) [3] . Reapers are essential for timely harvesting of field crops. Manually operated harvesting equipment is available, using a ground wheel as the power source to operate the cutter bar. However, the available traction force in the ground wheel is insufficient to cut and convey the crop. Additionally, the reapers currently on the market (both self-propelled and tractormounted) are high-cost and not eco-friendly. Due to their high initial and operating costs, small and marginal farmers cannot afford to adopt them. Considering all above facts, there is a need of a machine which can fill the gap between sickle and tractor/power tiller/self-propelled reapers for small and marginal farmers and also considerably cheaper and eco-friendly. By using battery as a power source, it can be boon for remote as well as hilly locations. Its battery pack can be use as power grid in remote areas where continuous electricity is a challenge. Battery packs are playing a crucial role in remote areas of Chhattisgarh, addressing the persistent issue of unreliable power supply. In regions where electricity infrastructure is limited or non-existent, battery packs provide a dependable source of energy for various needs, from lighting homes to powering small appliances and mobile devices. Battery technology is helping bridge the energy gap, improve living conditions, and enhance economic opportunities for rural communities.

Materials and Methods

The walk behind type battery-operated vertical conveyor reaper was developed by keeping in a view literature review, farming patterns and personal correspondence. The reaper consisted of cutter blade, battery, DC motor, chain conveyor, ground wheel, handle, and transmission system. The power is transferred from the DC motor to the counter shaft. From the counter shaft, power is then transmitted to the cutter bar through a vertical shaft and conveyor chain. The ground wheel receives power from the counter shaft with the help of a chain and sprocket arrangement. Current flows from battery to power controller and from there it goes to motor in specific manner. Accelerator and forward reverse button were connected with power controller to regulate the current so the speed of the machine. The methodology adopted for design and development of vertical conveyor reaper is discussed below:

Design of battery-operated vertical conveyor reaper

In machine design process, the physical and engineering characteristics of paddy and wheat crops are taken in to account. Various components of the harvester are engineered to endure any operating condition successfully. Additionally, a field test is conducted to assess the machine's performance. The design and selection of appropriate reaper component involves following steps: 1. Power requirement 2. Power source 3. Power transmission unit 4. Crop cutting unit 5. Crop conveying unit and, 6. Machine transporting unit e.g., Ground wheel and handle 7. Frame

Power requirement

The power requirement for cutting the crop using serrated type cutter blade was taken as 0.53 hp/m length of cutter bar and power required for conveying cut crop as 50% of the cutting power. Cutting width of the developed reaper was taken 1000 mm. Hence, the total power requirement for cutting and conveying unit was taken as 0.77 hp. Again power required to propel the machine is estimated by using following equation Where R r = Rolling resistance, Fs = Forward speed of the machine, 2.3 km/h e.g., 0.63 m/s R r = Coefficient of rolling resistance × weight of machine Let the assume coefficient of rolling resistance be 0.2 (for agricultural soil) and weight of the machine was 121 kg.

Power (Wr) = 0.20 hp or 0.15 kW Assuming 90% power transmission efficiency, so requirement for propelling the machine is 0.22 hp or 0.16 kW.

Total power required P = 0.77 + 0.20 P = 0.99 hp = 745 Watt Assuming 90% of the power transmission efficiency. P = 745/0.9 P = 827.8 Watt Thus, a DC motor of above 827.8 W should be used.

Power source

Power source include electric power i.e., battery and DC motor.

2.1 BLDC motor served as the machine's main engine. It uses electrical energy to produce mechanical power. For the development of the prototype reaper, a DC motor with a 900 W rating was chosen based on calculations and market availability. It operates at 480 rpm with a full current supply and 48 V potential variations. Table 1 provides the technical information of the DC motor, and Fig. 1 shows the DC motor and Fig. 2 displays the circuit schematic. Type BLDC motor 3.

Calculation for size of battery pack

After the selecting the motor, decided the range of the reaper, and here we were aiming maximum speed 2.3 km/h for 2 hours of field working of E-prime mover it means designing a battery pack for a range of 10 km/h and current drawn by the motor in this speed is calculated below: Ah = 18.75 A After finding the current drawn by the motor, we need to consider acceleration current. While accelerating motor draws more current and in deceleration draws less. So, in this condition some current loss will be there and we take that loss as acceleration current. Here we take it 5%, then

Selection of battery

Lead-acid batteries offer several advantages over lithium-ion batteries in certain applications. They are more cost-effective, with lower initial purchase and replacement costs, making them a practical choice for budget-conscious users. Lead-acid batteries also have a higher tolerance for overcharging and deep discharges, making them suitable for applications where occasional misuse may occur. Additionally, lead-acid batteries are widely available and have a well-established recycling infrastructure, reducing environmental impact. These factors make lead-acid batteries a preferred option for applications such as backup power systems, stationary energy storage, and certain types of vehicles where cost and durability are prioritized over energy density and weight.

Considering the above factor and after finding of required total battery pack capacity, a 48V, 55 Ah lead acid battery was selected to run a motor of 900 W, 48 V. For making a battery pack, four 12V, 55 Ah lead-acid batteries were connected in series to achieving desired battery pack capacity. A single 12V, 55 Ah battery shown in Fig. 3 and detailed specification of leadacid battery given in Table 2.

Design of power transmission system

The power transmission system was design to operate the conveyor, cutter bar and ground wheel of the developed prototype reaper. The power is supplied from BLDC motor to conveyor, cutter bar and ground wheel. The power was transmitted with the help of chain and gear drive. The transmission system consists of motor shaft, counter shaft, primary shaft (vertical), secondary reduction shaft and ground wheel shaft. The arrangement of the transmission system is shown in Fig. 4 and5.

Selection of crop dividers and lifters

The crop divider guides the machine to insert the lifter in the crop smoothly for proper cutting or harvesting of crop. The crop dividers are shown in Fig 3 .18. Star wheel type crop lifter was used for lifting the crop. Star wheel for each row is driven by the lugs attached to the vertical conveyor chain thus guiding the plant to the cutter bar. The speed of star wheels is depending upon the forward speed of the machine as they handle the plants to be cut. Star wheel and lugged on conveyor chain do the job similar to that of a reel in case of conventional header unit.

Ground wheel

Two pneumatic wheels of size 100×200 mm and 400 mm diameter were used as transportation wheels to make easy movement of machine in the field. Each wheel was fastened to a 25 mm shaft. With the help of bearings and shaft, the ground wheels were mounted at the centre of frame, as shown in Fig. 3.19. To make self-propelled, the ground wheel shaft received power from motor shaft through three reduction units.

Handle

The handle of the machine was designed on the basis of the working position of the operator easy working and shoe/floor friction and subject to anthropometrics. The co-efficient of friction (μ) between operators' shoe and the soil surface was 0.

Design of frame

It was a structural configuration, founded on the arrangement and placement of diverse constituents within the machine. A structural framework was devised to accommodate all the parts of the developed reaper, as depicted in Fig. 12. The material selection was of paramount significance to endure the full operational load. A mild steel square frame of 1000 x 840 mm 2 was constructed using MS square pipe of 35×35×3 mm to accommodate various components of the machine-like battery, d. c. motor, gear box, transportation wheels, handle, crop cutting, and conveyer and ground wheel.

Development of Battery-Operated Vertical Conveyor Reaper

A battery-operated reaper was designed and fabricated. The developed harvester was consisting of various parts i.e., main frame, DC motor, battery, cutter bar unit, conveyor unit, handle, crop lifter and divider, star wheel, ground wheel and power transmission system. The schematic conceptual drawing of the developed harvester was done using Solid work and the different components of developed machine are shown in Fig. 12 and13. The developed reaper is depicted in Fig. 14.

Conclusion

Manual harvesting is done by using sickle and it requires more time and drudgery. Combine harvesters and self-propelled reapers exhibit superior efficiency, requiring less time and delivering high field capacity compared to manual harvesting. However, these machines entail substantial costs and complexity, posing challenges for uneducated farmers. The majority of small and marginal farmers in India face difficulties in procuring these machines due to their high initial costs. While an alternative option is custom hiring, it remains problematic for those with small and fragmented lands. Harvesting through tractor-operated or power tiller-operated reapers incurs significant initial costs, running cost, and contributes to environmental pollution through fuel combustion. Hence, there is a need which bridges the gap between sickles and tractor/power tiller/self-propelled reapers, specifically tailored for small and marginal farmers, while also being significantly more cost-effective and environmentally friendly. Employing a battery as its power source, this technology could prove advantageous for both remote and hilly terrains. Furthermore, its battery pack can function as a power grid in remote areas, addressing the persistent challenge of maintaining continuous electricity supply. Therefore, a project was planned to develop a self-propelled battery powered reaper, having cutting and conveying unit powered by battery for paddy and wheat crop which will be within the affordable range of small and marginal farmers. In this era dominated by fossil fuels, battery-powered machinery is being introduced in automobiles. Similarly, in farming, the use of battery-powered equipment can be widely adopted to help reduce the burden of fuel costs for farmers.

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