Suitability of a laser rangefinder to characterize

Authors: Detlef Ehlert Michael Heisig Rolf Adamek

Publish Date: 2010/09/17

Volume: 11, Issue: 6, Pages: 650-663

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Abstract

In recent years laser rangefinder sensors have been introduced to the practice and research of agricultural engineering In research laser rangefinders have been investigated in horticulture and agriculture For vehiclebased determination of crop biomass commercially available laser rangefinders have been analysed and tested to measure aboveground biomass in oilseed rape winter rye winter wheat oats and grassland Resulting from limited measuring range and fixed beam types the laser rangefinder models that were investigated only partially met the specific demands for agricultural field and crop conditions Therefore a new laser rangefinder scanner ibeoALASCA XT was chosen This sensor was specifically developed for driver assistance and autonomous guiding of road vehicles The scanner was tested in 2008 focusing on the measurement of crop stand parameters in winter wheat under field conditions The sensor achieved good results with reproducible measurements Measuring from a stationary vehicle the standard deviation for the measurements of crop height to characterise the crop stand was less than 3 mm in low medium and high biomass areas The ground speed of the vehicle ranging from 6 to 24 km h−1 did not significantly influence the readings For measurements in front of tractors and selfpropelled machines field sprayers combines and forage harvesters the sensor has to scan the crop stands at different inclination angles It was shown that the inclination angle of the laser beam which varied from 10° to 80° significantly influenced the readings Higher inclination angles resulted in apparent increased heights of the crop stand For the functional relationship between reflection height levels 95th 75th 50th and 25th percentiles and mean values and crop biomass density the coefficient of determination R2 was greater than 09

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