Agriculture Reference
In-Depth Information
Table 12.5
Evaluated systems for yield measurement in sugar cane harvesters
Relative
calibration error
in % (average)
Stand. dev. of
relative error
in %
Measurement
system
Placement
of system
Authors
Pressure-
measurement
Chopper and
elevator
Cox et al. (
1998
)
10.0
No record
Weigh scale
Elevator fl oor
Benjamin et al. (
2001
)
11.0
No record
Weigh scale
Elevator fl oor
Molin and
Menegatti (
2004
)
−3.5
6.1
Weigh scale
Elevator fl oor
Cerri and Magalhaes
(
2005
)
1.0
4.7
Fiber optic sensor
Elevator fl oor
Price et al. (
2011
)
7.5
6.3
cotton weight as it accumulates in the basket (Searcy et al.
1997
) or with optical or
microwave sensors in the cotton conveyor pipes. The sensor readings are converted
into mass fl ow by calibration algorithms (Wilkerson et al.
1994
,
2001
; Durrance
et al.
1998
; Khalilian et al.
1999
; Vellidis et al.
2003
; Sui et al.
2004
). The evalua-
tion results ranged from excellent to less than ideal. The most often reported prob-
lems involved dust and debris build-up on sensor faces. Presently systems for
site-specifi c sensing of yields are available commercially for cotton pickers and
cotton strippers from AGLEADER, AGRIPLAN, CASE IH and JOHN DEERE.
A high activity in sensor research, development and evaluation was oriented at
making systems available to continuously detect mass fl ow and yield of
sugar cane
in self propelled chopper harvesters (Table
12.5
). Cox et al. (
1998
) developed and
evaluated a hydraulic pressure measurement system placed in the chopper and
elevator system to determine the material fl ow rate. A number of other concepts was
based on weighing systems placed in the elevator fl oor of the harvesters (Benjamin
et al.
2001
; Molin and Menegatti
2004
; Cerri and Magalhaes
2005
; Mailander et al.
2010
). Problems observed with the weighing systems were the compensation of tilt
and vibration as well as varying tare caused by soil, sediment and debris sticking.
A sugar cane yield sensing system that is based on fi ber optic fl ow sensing was
described and evaluated by Price et al. (
2007
,
2011
).
Other crops for which continuously sensing material fl ow and yield measurement
systems have been developed and evaluated are peanuts (Perry et al.
1998
; Vellidis
et al.
2001
; Thomasson and Sui
2004
; Porter et al.
2012
), peas (Glancey et al.
1997
),
tomatoes (Pelletier and Upadhyaya
1998
), grapes (Tisseyre et al.
2001
), and pistachios
(Rosa et al.
2011
).
12.7
Quality Sensing of Harvested Material
In the future besides geo-referenced yield measurement, online detection of the
quality of harvested products will gain in importance. Only the combination of
quantity and quality allows site-specifi c evaluation and targeted control of plant
production. To measure the site-specifi c moisture content of grain for up to 30 % on
