Evaluation of general-purpose lifters for the date harvest industry based on a fuzzy inference system

Most dates are still harvested manually around the world because a mechanized method that covers all the needs is not available. General-purpose lifters of various models are used for date harvesting in some orchards in Iran which is the second largest world producer. In this research the Mamdani Fuzzy Inference System (MFIS) was used to evaluate and classify 10 different lifters on the market to find the most suitable one for date plantations in Iran. Five principal lifter features including working height, length, width, payload and price were selected for comparison. To assign membership functions to each lifter feature, the values of tree spacing, tree yields and tree trunk heights were used. The required data were measured in a survey from 9 orchards in Bam and Shahdad cities (two big producers of dates in Iran). Initial analysis of data showed that two features of all studied lifters including width and payload were in required range for working in date groves, therefore, these features were not included in the fuzzy evaluation system. The lifters were graded by both a human date grower expert and the MFIS. Classified results obtained from the MFIS showed 85% general agreement with the results from the date grower expert. Based on the results, a lifter with 12 m of working height, length of 4.1 m and price of 27 million Iranian Rials (€2000) was found as the most suitable harvester for the studied region. The results showed that any new designs of date harvester for studied region must be able to reach to a working height of maximum 13.5 m. Lifters need to have a length of less than 3 m and must be cheaper than 40 million Iranian Rials (€3000). This technique could be used to evaluate and classify any new date harvesting alternative.