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Geometrical analysis of the 3-point linkage of tractors for the measurement and display of the working depth

Author : Dr Sanjay Kumar

Year : 2024

Publisher : Czech Academy of Agricultural Sciences

Source Title : Research in Agricultural Engineering

Document Type :

Abstract

The display of the depth of operation on tractors’ dashboards facilitates the operator in achieving precise operation. In this study, the depth of operation of a mounted implement was measured and digitally displayed on a tractor’s dashboard. The change in depth of operation was sensed by measuring the rotation of the rocker arm of the tractor’s hydraulic system. The measured angle of rotation was multiplied by a calibration factor to convert it into the actual depth of operation in centimetres. For the calibration factor, a geometrical analysis of the three-point linkage was carried out, and a mathematical relationship was established based on the length of various linkages and their locations. A computer program was also developed to solve these equations to calculate the calibration factor. The program was validated with six different sizes of three-point linkages and found the maximum root mean square error was within 5%. The developed digital display was evaluated in the laboratory with three different implements and found a maximum error of ± 1 cm. A further evaluation was also carried out in an actual field with implements at three different depth levels, and a deviation of up to ± 13% was found with respect to the manual depth measurement.