This paper is presented as part of a workshop case study of my PHD degree in University of Newcastle upon Tyne, England,1998. The subject of my extended research has been on new advanced Precision Farming Technologies which is presented by the author in ASABE world conferences in USA.

1. SIMULATED SLOPES ON A TEST RIG
BASED EVALUATING CONTINUOUS
CEREAL YIELD METERING ACCURACY
A Case Study of Workshop Experience
SANAEI, AKBAR; PhD
. Assistant Professor, Agricultural Engineering Machinery Dept
ISLAMIC AZAD UNIVERSITY-EGHLID BRANCH-IRAN
Director, First Iranian Applied Research Centre of Advanced
Machinery and Technologies in Precision Farming at IUT
sanaeia@yahoo.co.uk Email: Akbars@cc.iut.ac.ir or
1

2. ABSTRACT


Yield mapping as a prerequisite of “precision
farming evolution” needs more both field and
laboratory investigations for wide varied
slope effect based crops combining as an
important influenced factor.
Naturally, optimised precision and accuracy
of continuous crop yield metering on
combine harvesters requires more detailed
studies on points such the field-slope
variations which affect not only on soil
characteristics and in-field spatial crop yield
but it is a serious problem to measure the
reliable continuous spatial variable yield
variations during combine harvesting.
2

3. ABSTRACT2



Author through his practical studies
conducted at Nafferton research Farm of
Newcastle University in UK found out very
varied topographic aspects.
Previous author’s experiences in both
workshop and fields showed that the slope
affects accurate yield measurement
through combining crops (Sanaei, A.
2008).
Then the research was extended to design
and construct a test rig using clean grain
elevator’s parts of Class Combine for more
controlled fruitful trials by simulating
varied slopes (pitch and roll) in workshop
3
site.

4. Objective & Method





Today, there are only a few harvester combines
with installed full package of yield meter kits
equipped with a slope (both Pitch and Roll) sensor
as well.
These studies showed that the accuracy of Ceres2
also may be improved by adding an optional
hillside slope sensor.
It measures the angle of side-slopes and the
instrument will correct the yield measurement for
the effect of the slope sensor location.
This paper examined and analysed data of
multidimensional detailed wide range of slope
effects between 0-15 degrees on measuring yield.
This was done through accessing to algorithmic
models by installing previous version of Ceres2
yield meter on constructed test rig which showed
comprehensive results including significant
differences on yield meter accuracy.
4

5. INTRODUCTION



As previously mentioned, accurate and precise
yield monitoring and mapping on a combine
harvester is yet a serious prerequisite for more
processing of other stages of a successful
precision farming project.
Based on the above concept, author decided to
carry out comprehensive laboratory slope tests in
his more advance research project according to
basic works of Ciha (1984) ; Reitz & Kutzbach
(1994); Kent et al.,(1990); Sanaei & Yule (1995);
Sanaei & Yule (1996) and Hammer et al., (1995)
for the improvement of Ceres2 instrumented
combine harvester based yield measurement.
Hence, following the multiple fields yield
monitoring experiments and data collection during
harvest 1994-95, a preliminary laboratory
experiment was conducted to investigate the
continuous crop yield monitoring on the combine
harvester affected by both pitch and roll slopes
5
(Sanaei, A. 2008).

6. Previous Works



The first-year results of these field and
stationary grain combining workshop experiments
based continues yield monitoring on Deut Fahr
combine harvester on Nafferton research farm of
Newcastle University-UK (Sanaei, A.1999),
indicated that factors such as slope (pitch and
roll), changing travel and elevator speed, and
wheel slip might have an effect on the accuracy
of measured yields.
These special limited workshop trials of the slope
effects (over a range of 0-10 ° for various sides
and up/down hill slopes) on stationary working
combine performance in 1995 emphasized on
existence of significant difference in yield
measurements (Sanaei A. 2008).
These tests confirmed that both pitch and roll
6
may change the measured yield significantly.

7. ?Why Decision for Test Rig Method



Because, author decided again to conduct more
precise and comprehensive workshop tests to
measure slope's effect over a wider slope range
of pitch and roll (0-15 ° ).
For this, a reliable experimental test rig was
started to design and construct pre-harvest
1996 which was delayed until February 1997
because of provided parts delay.
This experiment was included more detailed
slope trials with four orientations of clean grain
elevator slope position as well as other related
trails for some more influenced factors such as
clean grain elevator speed .
7

8. MATERIALS AND METHODS






The test rig design comprises two funnel shaped
discharge and feeding grain bins fitted on the main frame
skeleton (Figure 1).
A magnetic speed sensor was constructed , the magnetic
core fitted on the driven shaft of an electric motor and the
probe connected to Hermes data logger.
A speed converter changed and controlled the rotary
speed of this electric motor where appropriate.
A door at the bottom of the upper bin could be opened as an
end point of each test to discharge the grain from discharge
tank into feeding tank.
Another door on lower bin admitted an adjusted amount
of grain into bottom auger based on a fixed line for the
whole experiment.
Three parts; clean grain elevator (part No: 682765.0 for
the Dominator 218) plus, discharge auger and bottom auger
(filler tube) were provided by CLAAS Combine Company in
Germany and modified to fit the test rig.
8

9. Figure 1- Instrumented Test Rig construction
and configuration, February 1997
9

10. Test Rig Components Design





The grain elevator was fitted vertically based on
the manufacture’s instructions.
The Moisture sensor was fitted on the discharge
auger just above the discharge bin and the yield
sensor parts were installed inside of the upper
part of clean grain elevator.
The paddle chain elevator was powered via a 540
rpm PTO of a ZETOR tractor through a driving
system.
This driving system includes a triangle frame to
carry a gearbox with a shaft for changing the
rotation direction of PTO drive shaft.
The driven shaft of the gearbox is connected to
main drive shaft of the pulleys (SPA 140-3 2517
& SPA 250-3 2517) and belt (SPA 1600) via
universal drive shaft. The diameters of two
slotted pulleys fitted on the main drive shaft and
bottom or cross auger shaft were 140 and 250
10
mm respectively.

11. RPM output =
di
140
× 540rpm =
× 540 = 302.4
do
250
Test Rig Design Calculations
11

12. Other Test Rig Components



The other main part of the test rig was a
four-wheeled carriage base , which could be
used to make small changes in slope and
for transportation.
The steeper slopes were made using a
hydraulic jack and a 2 tonne hydraulic
mobile crane.
A magnetic speed sensor was constructed
and fitted on the shaft of an electric motor
connected to a transformer to provide
signals with smooth factor of 7 seconds
based on a normal forward speed of the
combine (4.7 km per hour).
12

13. Yield Meter Calibration




The Ceres2 yield-meters was calibrated and set up
based on manufacture instructions (issue 09,
7/5/96, NG 406-537).
Two plastic protractors equipped with a hanging
weight bar fitted on both sides of grain elevator
indicated degree of slope for each treatment.
The constructed Test Rig after final setting up and
rechecking for insured reliable work of all sensors
and fitted instruments was used to conduct
reliable tests of Ceres2 yield sensing based on
both precise and accurate Ceres2 yield meter
calibration.
This was conducted by fitting four load cell units
on each corner of the discharge grain tank.
13

14. Data Logger and Signals



The signals sent from four load cells
attached to discharge tank via connection
to an electronic data logger ‘Signal Centre’
could record the momentum.
This load cells was connected to four
separate channels of the ‘Signal Centre’
data acquisition system to save the
continuous data signal records of grain flow
rates continuously.
This was done during accuracy tests of
Ceres2 yield sensor based on loading a
precise weighted amount of wheat kernel
on the feeding grain tank.
14

15. Elevator Speed Based Yield
Measurement Tests



Ceres2 yield sensor accuracy was
examined for different elevator speeds
within a range of 180-300 rpm with an
increment of 20 rpm in level condition.
Trial 5 on the test rig was included a
number of these tests.
This chain processing showed the
actual relationship between different
speeds of grain elevator and yield
measurements.
15

16. Slope Based Yield Measurement Tests







This part of experiment was carried out with
slopes from 0-15° in one degree increments for
each treatment of trials in four oriented sides of
test rig and achieved data were analysed
statistically in Excel spreadsheet
1. Trial 1 Rear Slope (RS)
2. Trial 2 Front Slope (FS)
3. Trial 3 Left-hand side Slope (LHS)
4. Trial 4 Right-hand side Slope (RHS)
Each treatment was carried out by feeding a
definite amount of grain (384 kg. wheat) into the
system with three replications for up and down
(pitch) slopes and two replications for side (roll)
slopes.
Even though each treatment contained a
significant number of signal records for the yield
measurement but more replications ensured the
reliability of tests by producing a larger number of
16
records.

17. Test Rig Based Slope Tests Conditions




The number of records and the time needed for
each test varied from 30-80 records within 2-7
minutes.
Each test was initiated by simultaneously
activating the yield meter to log the records and
opening the slide door at bottom of feeding grain
bin.
Each test was terminated when the yield meter
monitor displayed a ‘0.00’ for moisture and
received yield signals.
With the purpose of providing more even
conditions for the whole experiment of each
orientation the tractor’s engine was operating
17
continuously without changing in rpm or other

18. RESULTS AND DISCUSSION




Slope Tests:
Ceres2 measurements at a range of slopes were
corrected relative to GCF calculated in the level
situation to achieve the actual mass of the grain
(Table1-third column).
Comparison of corrected Ceres2 yield records
(kg) of each slope test relative to corrected yield
(384 kg) in the level situation gave errors up to
58.8% at 15 ° at right slope (Table1-last column).
In overall, the results demonstrated that
increased downhill slope decreased yield
measurement while increased uphill slope
increased it with a maximum 31.8 % error for both
situations .
18

19. Table1) Calculated yield errors at test
.rig slopes relative to level situation
19

20. :Elevator Speed Effect- 2


Yield measured by Ceres2 RDS
Tech. consistently decreased when
elevator speed was increased within
180-300 rpm (Figure 2).
Observations results 3 to 18 showed
peak variations of yield measurement
for variable grain elevator speeds on
the test rig.
20

21. Figure 2- Plots over the elevator speeds range
.of 180-300 rpm showed a negative relationship
9
Yield Variation Plots on Variable Elevator Speed
Observations 1- 31, Test Rig-1997
8
180 rpm
Yield: t/ha
7
6
5
4
300 rpm
3
2
1
0
Observations/tim e
T24/180rpm
T21/260rpm
T19/200rpm
T22/280rpm
T23/220rpm
T28/300rpm
T20/240rpm
T27/303rpm
21

22. Figure3- Plateau yields variation plots for
variable elevator speeds on the test rig-1997
Yield: t/ha
Effect of Variable Elevator Speed on Yield
Measurement Test Rig 1997
9
8.5
8
7.5
7
6.5
6
5.5
5
4.5
4
180 rpm
180 rpm
200 rpm
220 rpm
240 rpm
260 rpm
300 rpm
1
2
3
4
5
6
7
280 rpm
8
9
10 11 12 13 14 15
Peak observations from 3-18
22
300 rpm

23. Figure 4- Linear regression of yield against variable
( elevator speed-test rig 1997 (data:3 to18
The mean of yield observations 3 to 18
(figure3) indicates a negative relationship
between measuring yield and elevator
)speed (r sq= 0.97***) (Figures 4
RPM Line Fit Plot-Elevator Speed Trial
Test Rig-1997
10
Observations:3 to 18
8
6
4
Residuals
Yield:t/ha
RPM Residual Plot-Yield/Elevator Speed Trial
Test Rig-1997
y = -0.4779x + 8.2771
R2 = 0.95
2
0
0
1
2
3
4
5
RPM
Yield:t/ha
6
7
0.4
0.2
0
-0.2 0
-0.4
-0.6
1
2
3
4
RPM
Linear (Yield:t/ha)
23
5
6
7

24. Other regression used the whole
).data of the tests (Figure 5


Though, this model shows a high negative
correlation (r sq= 0.90***) between yield
measurements and elevator speed.
The residuals plot does not confirm the
linearity of the model.
24

25. Figure 5- Linear regression of elevator speed
(against yield and residuals (whole data
Yie ld: t/ha
Rpm/Pto Line Fit Plot-Elevator Speed Trials
Test Rig-1997
8
6
4
y = -0.0138x + 8.5135
R2 = 0.9045
2
0
150
200
250
Rpm /Pto
Yield: t/ha
Residuals
2
Linear (Yield: t/ha(
Residuals Plot of Linear Yield/Speed Elevator
Trial
Test rig - 1997
1
0
-1 0
2
4
6
8
-2
Ele vator speed/rpm
Linear Residuals
25
300

26. 
Figure 6- Quadratic regression of elevator
speed against yield and residuals (whole
(data
Using the whole data, a second order
polynomial regression (Figure6) improved
and removed the trend in residuals (Table 2).
Elevator Speed Line Fit Plot-test rig/1997
RPM/pto Residuals Plot-Polynomial Model
6
4
2
Residuals
Yield: t/ha
8
y = 0.0001x 2 - 0.0714x + 15.337
R2 = 0.9815
0
150
200
250
300
Speed/rpm
Yield: t/ha
Poly. (Yield: t/ha(
0.15
0.1
0.05
0
-0.05 4
-0.1
-0.15
4.5
5
5.5
rpm/pto
Residuals
26
6
6.5

27. Table 2- The regression equation
27

28. Slope Test Discussion



1- Slope Effect: Ceres2 yield error at each slope
could not be estimated because of using a
definite batch of the grain for each trial and the
technical problem of cascading back and down
the grain into the bottom auger and elevator
respectively.
These tests also completely confirmed findings
of 1995 Ceres2 tests on the stationary working
combine and need to develop models based on
a practical range of field slopes (i.e. 0°- 30°) for
each orientation of different combine types and
models.
Indeed, without implementing these slope
sensors, Ceres2 yield measurements would not
be reliable under realised field slope conditions.
28

29. Speed Test Discussion


2- Elevator Speed Tests: The importance
of using a constant combine velocity and
elevator speed is recommended by Birrel
et al., (1995) and Schueller (1983) to
keep a steady grain flow for reliably
measuring yield.
However, the speed may change when
entering and leaving the crop, at headlands and when combining very dense
and moist standing crop or over-loading
grain into elevator (Klemme et al, 1992;
Reitz & Kutbatch, 1993, 1995).
29

30. Conclusion




In general, the above test rig experiments
suggested both linear (r sq= 95 %***) and 2nd
order polynomial (r sq= 98 %***) models of yield
variation with elevator speed between 180-300
rpm.
These correspond with a mean yield difference
between 5.5 to 8.5 t/ha (Figures 2-6).
This revealed serious errors of excess yield up to
54% when the combine elevator speed decreased
from 300 to 180 rpm.
Though yield errors affected by unexpected
changes of speed might be removed to improve
data, the performance of each type and model of
combine harvester will require testing to preserve
a constant elevator and travel speed under
fluctuated field conditions when harvesting.
30

31. References


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
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
Birrel et al. (1995).
Ciha, A. J. (1984). Slope Position and Grain Yield of Soft White Winter Wheat.
Agronomy Journal , 76 , PG193-196.
Reitz, P., & Kutzbach, H. D. (1993). Measurement Techniques for Yield Mapping
During Grain Harvesting With Combine. In XXV CIOSTA CIGR Congress , (pp. 4853). Germany
Reitz, P., & Kutzbach, H. D. (1995). Investigations on a Particular Yield Mapping
System for Combine Harvesters. Computers and Electronics in Agriculture , 14 ,
137-150.
Hammer, R. D.; Young, F. J.; Wollenhaupt, N. C.; Barney, T. L. & Haithcoate, T.
W. (1995). Slope Class Maps from Soil Survey and Digital Elevation Models. Soil
Science Society American J. , 59 (-), 509-519.
Klemme et al. (1992)
Kent et. al. (1990)
Yule, I. J. ; Sanaei, A. ; Hodgkiss, A. & Korte, H. (1995). Yield Mapping
Combinable Crops: Field Experience, Problems and Potential. In Agricultural And
Biological Engineering Conference; New Horizons, New Challenges , 1 (pp. 2).
Newcastle - England: University of Newcastle Upon Tyne. England
Sanaei, A. & Yule, I. J. (1996a). Accuracy of Yield Mapping Systems: The Effects
of Combine Harvester Performance. AgEng’96 Conference, Paper 96G-016.
Madrid. Spain
8.
Sanaei, A. & Yule, I. J. (1996b). Yield Measurement Reliability on
Combine Harvesters. In ASAE (Ed.), ASAE Annual International Meeting , Paper
No. 961020 (pp. 14). Phoenix Arizona: ASAE. USA
9Sanaei, A. (1998).Instrumented Combine Harvester Based Related Yield
Mapping Aided by GIS/GPS. Unpublished PhD Dessertation. Agricultural and
Environmental Science Department. University of Newcastle Upon Tyne.
England.
10Sanaei, A. (2008). Slope and Wheel Slip’s Variations Based Continuous
Cereal Yield Monitoring on Combine Harvester Aided by GPS/GIS. A case study
of field-workshop experience. World Conference on Agricultural Information and
IT-IAALD AFITA WCCA, Tokyo, Japan, 24-27 August, 2008
31