CALIBRATION OF EORT (EXTENDED OCTAGONAL

RING TRANSDUCER)

FOR DRAFT REQUIREMENT IN TEST SOIL BIN

Er. Saurav Kumar SahooB.Tech (Agricultural Engineering)OUAT, Bhubaneswar, Odisha.2013-14

CALIBRATION OF EORT (EXTENDED

OCTAGONAL RING TRANSDUCER) FOR DRAFT REQUIREMENT IN TEST SOIL BIN

SUBMITTED BY :Saurav Kumar SahooB.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

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.

To Calibrate the EORT.

To Establish a relationship between Draft and Electrical

Strain measured in EORT.

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 .

TEST SOIL BIN FITTED WITH EORT

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.

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

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.

Pulley Arrangement With Loaded Spring Dynamometer

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.

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 Electr ical Strain of EORT

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 .

Plot between Applied load Vs Electrical signal (Individual Observation)

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.

Final Average Plot between Draft Vs EORT Electrical Strain

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

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.

Thank you