Calibration of Extended Octagonal Ring Transducer for draft requirement in soil, measured by running Mould board plough through soil in Test Soil Bin.

1. CALIBRATION OF
EORT (EXTENDED OCTAGONAL
RING TRANSDUCER)
FOR DRAFT REQUIREMENT
IN TEST SOIL BIN
Er. Saurav Kumar Sahoo
B.Tech (Agricultural Engineering)
OUAT, Bhubaneswar, Odisha.
2013-14

2. CALIBRATION OF EORT (EXTENDED
OCTAGONAL RING TRANSDUCER) FOR DRAFT
REQUIREMENT IN TEST SOIL BIN
SUBMITTED BY :
Saurav Kumar Sahoo
B.Tech. (Agril. Engg.)
saurav.pupun@gmail.com
Under the Guidance of
Dr. Debaraj Behera
HOD, Deptt of FMP
College of Agricultural Engineering & Technology
Bhubaneshwar, Odisha

3.  When soil is disturbed by any mechanical means, various forces act
on the soil engaging tool by virtue of the soil resistance
 Various forces acting on tool is required to determine the power
requirement.
 The force on the tillage tools can be determined with better
accuracy in a test soil bin.
 Octagonal ring transducers are now the most commonly used and
research work for its continued improvement is going on.

4.  To Calibrate the EORT.
 To Establish a relationship between Draft and Electrical
Strain measured in EORT.

5.  The experiment was conducted in the Farm Power laboratory
of the College of Agricultural Engineering and Technology,
OUAT, Bhubaneswar.
 The TEST SOIL BIN was used to conduct the Experiment.
 The soil bin comprised a stationary bin 16.0m long, 1.8m wide
and 0.6m deep, a carriage system, implement and soil
processing trolleys, power transmission system, control unit
and instrumentation for draft measurement .

6. TEST SOIL BIN FITTED WITH
EORT

7.  An EORT uses the
principle of electrical
resistance change in the
strain gauges which are
mounted on the faces of the
EORT.
 Here electrical signals are
recorded and then they are
calibrated to give the
physical values for the
electrical value.
 Thus it has significant
application in draft
measurement of ploughs.

8.  Data acquisition from the various instruments at the soil bin is
done fully by automated Data Acquisition System
 In CAET soil bin set up data acquisition is done by HBM
Spider 8 (8 channels) data logger and CATMAN EASY
software package for recording of concerned data in the
computer.
 Control panel is the panel or switch board which houses all the
controls for the soil bin set up.
 It has the start, forward, reverse button on it to control the
movement of soil bin assembly over the guide rails

9.  For calibration of EORT known weights were used and
corresponding change in electrical Strain (in mV/V) was
recorded.
 To calculate draft a frame and pulley arrangement was
fabricated.
 A flexible and inextensible wire was attached with the hook
at the back of EORT .
 The wire was aligned to be perfectly horizontal with the
inner groove of pulley.

10. Pulley Arrangement With Loaded Spring
Dynamometer

11.  After the wire passes over the pulley, there was a hook to
carry the known weights during calibration.
 And the Corresponding electrical Strain experienced in the
EORT were measured for the corresponding Input weight and
were noted down.
 Then, the graphical relationship between Draft and electrical
strain was computed and the corresponding calibration
equation and R2 value was obtained.

12. Weight
(Kg)
Individual Observations of Electrical Strain of EORT (in mV/V)
Average Value (in
mV/V)
Obs. 1 Obs. 2 Obs. 3 Obs. 4 Obs. 5 Obs. 6 Obs. 7 Obs. 8
10 0.017 0.017 0.018 0.018 0.018 0.017 0.018 0.017 0.0175
20 0.03 0.032 0.031 0.031 0.03 0.031 0.032 0.031 0.031
30 0.043 0.041 0.036 0.042 0.043 0.041 0.041 0.043 0.04125
50 0.059 0.054 0.055 0.058 0.056 0.058 0.056 0.057 0.056625
60 0.072 0.069 0.074 0.073 0.072 0.071 0.072 0.07 0.071625
70 0.077 0.076 0.084 0.079 0.08 0.078 0.081 0.08 0.079375
80 0.097 0.088 0.089 0.09 0.092 0.089 0.093 0.092 0.09125
Observations of Draft Vs Electrical
Strain of EORT

13.  Data obtained from the experiment was analyzed and
represented in graphical form.
 When these data were analyzed a lot of erratic readings were
obtained, which might be due to friction in the pulley or the
breakdown/Malfunctioning of the EORT sensors and system .

14. Plot between Applied load Vs Electrical signal (Individual Observation)

15.  We found that the final output is just deviated from the trend
line and the lower value of R2=0.9869 were obtained.
 So as to overcome those losses and deviations, total Eight
(08) numbers of observations with the same Known input
weights were taken with intervals and the Average value of
the Electrical Strain readings on the EORT was taken into
account as the final and more accurate calibrated
Horizontal Electrical strain value of the EORT.

16. Final Average Plot between Draft Vs EORT Electrical Strain

17.  The calibration of EORT showed that the transducer
works well up to load of 800 N.
 Showed a high degree of linearity between bridge
output voltage and force applied.
 The minimum co-efficient of correlation, R2, found
was 0.9947.
 Calibration Equation: y=0.001x ´ 0.0089
 The test results for repeatability showed negligible
difference.
 The system is best suited for measuring draft of
tillage implements

18.  In the experiment EORT was used only to find
out horizontal draft force.
 But EORT can also be used for vertical and
side forces calculation.

19. Thank you