Assessment of forage mass from grassland swards by height measurement using an ultrasonic sensor
Computers and Electronics in Agriculture
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The main aim of this research was to develop and evaluate sensor system to create forage yield maps on a three-point linkage type of rotary mower-conditioner. The method was based on the mowing machine conditioner's power requirement measured by a torque sensor or on material change in momentum measured by a curved impact plate. Laboratory measurements were taken to determine the dependence of conditioner power input and signals from the impact plate on material mass flow. A mixture of grass and alfalfa was used. There was a very good linear relationship between the conditioner's power, impact force from an impact plate, and material feed rate through the mower. The calculated coefficients of determination (R^2) were about 0.95. It was possible to differentiate a material feed rate difference 0.5kgs^-^1 using either method. The effects of material changes and mower parameters on the accuracy of feed rate measurement were then measured. It was observed that the results form torque sensor was influenced by crop variety, maturity and intensity of conditioning. The same influence was not observed for impact plate. A field of 0.54ha was then harvested. A comparison of data from the torque sensor and impact plate with data from hand measurement were made by means of statistical and geostatistical analysis. Conditioner power input measurement and crop impact force were used to create grass yield maps.