Agriculture Reference
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Fig. 12.3 Material fl ow measurement based on belt weighing technology for a grass mower
(Demmel et al. 2002 )
Some research groups have published work on the development of material fl ow
measurement technology for tractor mounted grass mowers . The systems were
either based on a belt weighing technique (Fig. 12.3 ), on force and torque measure-
ment or on the application of a dielectric sensor for mass fl ow detection. Until now,
none of these developments is available commercially (Kumhala et al. 2001 , 2007 ;
Demmel et al. 2002 ; Wild et al. 2004 ).
Since 1990 research on material fl ow sensors for forage choppers is reported.
First investigations and results were published by Vansichen and De Baerdemaeker
( 1993 ). In 1995 Auernhammer et al. presented results of a comparison of material
fl ow measurement systems based on the clearance between upper and lower
feed rolls (volumetric), the power consumption of the cutter drum, the power
consumption of the blower and a radiometric measurement system (mass fl ow) in
the spout (Fig. 12.4 ). Barnett and Shinners ( 1998 ) investigated similar sensor con-
fi gurations on a trailed forage chopper.
As with yield measuring systems for combines, the material fl ow is converted
into the area yield (t ha −1 ) by referencing to the harvested area that is obtained from
the cutting width and harvested distance (wheel sensor). In addition, the harvested
area is used to determine the area output (ha h −1 ). Continuous yield sensor readings
(often 1 Hz) are combined with information from a satellite positioning system for
geo-referencing.
As an alternative for material fl ow detection in a forage chopper, Missotten
( 1998 ) developed and evaluated a system with a friction compensated curved plate
in the spout.
Some manufacturers of self propelled forage choppers (CLAAS, JOHN DEERE
and KRONE) are offering material fl ow and yield recording systems based on
displacement sensing of the feeder rolls - thus on volume fl ow - as options.
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