Geometrical analysis of 3-point linkage of tractors for measurement and display of implement's working depth

The display ofthe depth ofoperation ontractors' dashboards facilitates the operator inachieving precise operation. Inthis study, the depth ofoperation ofamounted implement was measured and digitally displayed onatractor's dashboard. The change indepth ofoperation was sensed bymeasuring the rotation ofthe rocker arm ofthe tractor'shydraulic system. The measured angle ofrotation was multiplied byacalibration factor toconvert itinto the actual depth ofoperation incentimetres. For the calibration factor, ageometrical analysis ofthe three-point linkage was carried out, and amathematical relationship was established based onthe length ofvarious linkages and their locations. Acomputer program was also developed tosolve these equations tocalculate the calibration factor. The program was validated with six different sizes ofthree-point linkages and found the maximum root mean square error was within 5%. The developed digital display was evaluated inthe laboratory with three different implements and found amaximum error of±1 cm. Afurther evaluation was also carried out inan actual field with implements atthree different depth levels, and adeviation ofupto±13% was found with respect tothe manual depth measurement.