Development of a Novel Draft Sensing Device with Lower Hitch Attachments for Tractor-Drawn Implements

Measurement of draft is important for designing and testing a tillage implement or seeding machinery. This study aimed to develop an instrumentation setup which can be mounted between any category of tractor and different tillage implements for accessing real-time draft values while carrying out tillage.

A novel draft sensing device was developed along with lower hitch attachment for different categories of tractor and implement by measuring horizontal force at each hitch point using three force sensing units. The force sensing unit comprised an S-type loadcell packed between two U-shaped frame and a microcontroller-based data acquisition system. The finite element (FE) simulation was made to examine safety of the designed structure.

The FE simulation result showed that stress induced on each element of force sensing unit was lesser than the yield strength of the material. The developed draft sensing device was tested both in the laboratory and in the field during tillage operation. The signals received from force sensing units were observed to be varied linearly with the applied load with negligible hysteresis losses.

The draft values measured by the developed draft sensing device were found to be accurate with mean absolute percentage error (MAPE), root mean square error (RMSE), and maximum absolute error (MAE) of 4.39%, 8.83 kg, and 7.14%, respectively.