Prediction of Draft Force and Energy Requirement for Subsoiling Operation with a Fuzzy Logic Approach

In this study، a knowledge-based fuzzy logic system was developed on experimental data and used to predict the draft force and energy requirement of tillage operation. In comparison with traditional methods، the fuzzy logic model acts more effectively in creating a relationship between multiple inputs to achieve an output signal in a nonlinear range. Field experiments were carried out in a sandy loam soil on coastal plain at the Edisto Research and Education Center of Clemson University near Blackville، South Carolina (Latitude 33˚ 21 «N، Longitude 81˚ 18» W). In this paper، a fuzzy model based on Mamdani inference system has been used. This model was developed for predicting the changes of draft force and energy requirement for subsoiling operation. This fuzzy model contains 25 rules. In this investigation، the Mamdani Max-Min inference was used for deducing the mechanism (composition of fuzzy rules with input). The center of gravity defuzzification method was also used for conversion of the final output of the system into a classic number. The validity of the presented model was achieved by numerical error criterion، based on empirical data. The prediction results showed a close relationship between measured and predicted values such that the mean relative error of measured and predicted values were 3. 1% and 2. 94% for draft resistant force and energy required for subsoiling operation، respectively. The comparison between the fuzzy logic model and the regression models showed that the mean relative errors from the regression model are greater than that from the fuzzy logic model.