mass flow rate measurement system performance on potato harvesters

a project was established to develop a procedure for the selection, design, installation, test and evaluation of mass-flow rate measurement systems for root crop harvesting and to assess the consistency and precision of the weighing systems incorporated into crop feed arrangements in both laboratory and field studies. studies were conducted to evaluate conveyor belt weighing systems using an experimental apparatus and a commercial potato harvester. two weighing systems were evaluated: (a) cantilever transducers fitted to the conveyor belt mechanism and (b) a load cell system supporting the total weight of the conveyor and crop. the results of laboratory studies with sugar beet/potatoes showed that the standard cantilever transducers gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.43 kg (connected to one idler roller) to 2.61 kg(connected to three idler rollers) with an appropriate value equal to 0.54 kg (connected to two idler rollers). the load cell supporting system also gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.56 kg (continuous side feeding) to 2.25 kg (side feeding from right side) with an appropriate value equal to 0.84 kg (steady state side feeding). experiments were conducted in the laboratory and field to assess the effects of belt inclination and extraneous vibration, transferred from the tractor to the harvester, on the measurements of crop mass. the results of field studies with potatoes using the cantilever transducers showed that the most precise system performance was obtained when using the 125 mm idler wheels with standard deviation of the mean experimental error of the sample yield equal to 0.99 kg. the results of barn studies with potatoes using the load cell supporting system showed that there was a good linear relationship between the measured and weighed mass of the potato samples with standard deviation of the mean experimental error equal to 0.34 kg.