Fabrication of Low Cost Automated Lime Colour Sorter
Abstract
Among fruit crops lime has high demand in the world. There are varieties of products being made from limes at various stage of maturity. Colour is the vital parameter of maturity indication of most agricultural produce s. Colour of lime produce varies from green to yellow. Although yellowish limes are preferred by some category of people and processers, for exporting purposes greenish limes are being used because of their longest shelf time. Thus , sorting based on its colour is crucial for consumer acceptability and al so for further processing. Both greenish and yellowish limes are harvested together and sorted through post-harvest operation of colour sorting. This is often performed by manual labourers . The main limitation associated with hand sorting is less accuracy , as human evaluation may vary person to person. The refore, automated grading system is becoming popular due to its superior speed, consistency, and accuracy. This paper discusses about a new approach to develop a lime colour sorter at a minimum price using TCS230 colour sensor . The identification of the colour is based on the frequency analysis of the output of TCS230 sensor . Arduino Uno was used to control ove rall process. Stepper motor was used to sort limes into two different classes. All the mechanical parts were designed through Auto CAD software. Fabricated sorter was tested at various environmental light intensities, the results shown there is no influences by the sexternal light.
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Introduction
As a group of fruits citrus has high demand in the world due to its cultural, social and economic impacts in our society. Among citrus, lime is the third most important fruit crop after orange and mandarin which is native to Asia [1]. Lime (Citrus aurantifolia) belongs to family Rutaceae, is grown tropical and sub-tropical countries in world [2]. In Sri Lanka it is grown in organized small orchards and home gardens in dry and intermediate zones. Uva and north western provinces are the major lime growing areas in Sri Lanka [3].
Lime is widely used for culinary and non-culinary purposes. It is consumed as beverages, refreshing drinks, pickles, jams, jellies, snacks, candies, and sugar boiled confectionaries, and culinary throughout the world. Extracted oil from the peel is extensively used in soft drink concentrates, body oils, cosmetics, hair oils, tooth pastes, toilet and beauty soaps, disinfectants, mouth washes, deodorants and innumerable other products [4]. The substances flavonoids, alkaloids present in limes have biological activity such as anti- bacterial, anti-fungal, anti-viral, anti-cancer and anti-diabetic activities [4].
In world, India, Mexico, Argentina, Brazil, Spain, China and United states are the main lime producers, in which Argentina is the world largest lime producer, produce over 1 million metric tons annually [5]. Extracted juice from the pulp and zest has high markets in the world and, it is prepared from ripened limes. Success of this liquor caused emergence of small industries in Sri Lanka also and it has positive impact in our economy.
In agricultural side, product quality and quality evaluation are the two most important parameters in food industries. The quality is improved through the postharvest operations of washing, sorting, grading, packing, storing and transporting [6]. When consider the lime, it is an oval or round, its colour varies from green to yellow, and it is harvested throughout the year. During harvesting, they are harvested together, because both green and yellow limes have demand at markets [7]. However, consumers, they prefer to have the things with similar shape, same size and similar colour [1]. These can be achieved through sorting and grading process.
Quality grading of many agricultural products can be made through its outer and inner parameters. The outer parameters are those size, shape, texture, colour intensity and colour homogeneity, and sweetness, acidity and incidence of disease are the inner parameters. Although in most, accurate classification of sorting is achieved by considering their colour and size [8], [9]. In general, the color of a produce indicates its level of maturity, and the presence of defects [10], [9], [11]. Thus, colour sorting gets its priority due to this reason.
This sorting process is done manually or through automated machineries. Despite, to provide good quality products within the short time automated grading system is becoming popular among farmer association [12]. This automated system is getting its priority due to its superior speed, consistency and accuracy. The traditional visual quality inspection of manual sorting and grading, which are performed by hired labourers is tedious, time-consuming, slow and inconsistent and also it is difficult to hire the labourers who adequately trained and willing to undertaken the tedious task [13], [14].
Therefore, this automated grading system in agriculture and related industry will help to supply the increasing demand for high quality food products as much as quick at the same time it will have positive impacts on growth and development of that particular industry [15]. Thus, researches in this field will help to freeing the people from traditional hand sorting and it will help to improve product quality [13]. There are several approaches for continuous recognition and sorting of objects according its outer parameter into desired location. But, this study focuses on a new approach and design for sorting, specifically for limes by using colour identification sensor TCS230, Arduino Uno a micro controller and stepper motor.
Conclusion
This machinery was designed to sort limes of particular size into two different groups, which are light green and green into one category , and light yellow and yellow into another category . Although, it also possible short into four categories, along with decayed one almost five categories possible based on this principle. The sensor TCS230 has ability to recognize and differentiate lime produce s more efficiently. In case of agricultural produces the colour distribution is not even all the time.
Thus, use of more than one sensor to sense several portion of these produce s will increase the accuracy and reliability of this sorting process. This system was developed for particular size group of lime s, which size is commonly used for exporting purpose. In future , it can be developed further as multi -diameter for sorting other size lime groups or in other way this same system can be used for other size as well by using flap valve mechanism for single feeding. To ensure the optimum feeding through the tunnel, vibrator can be attached at the hopper zone. Many of available sorters are fixed and their cost is high . This sorter was developed at minimum cost and it is a portable one. The real contribution of this system is that it i s able to save time of sorting based on colour. Thus, this system has a huge potential to go into the market with proper implementation. This mechanism can be used for other agricultural products as well including grains.
