Ethiopian Journal of Science and Sustainable Development

e-ISSN 2663-3205 Volume 9(1), 2022

Journal Home Page: www.ejssd.astu.edu.et ASTU

Research Paper

Modelling and Simulation of Hydraulic System to Measure Soil Compaction for

Agricultural Field

Yared Seifu1,, Someshakher S. Hiremath2, Simie Tola1, Amana Wako1

1Department of Mechanical System and Vehicle Engineering, Adama Science and Technology University, P.O. Box: 1888,

Adama, Ethiopia

2Department of Mechanical Engineering (Precision and Instrumentation Laboratory Engineering). (IITM) Indian Institute of

Technology, Madras University Chennai, India

Article Info Abstract

Article History:

Received 28 August 2021

Received in revised form

11 November 2021

Accepted 12 March 2022

Soil compaction is one of the negative factors associated in the top layer of the soil by heavy

agricultural machinery in the agricultural field that limits ploughing tool movement, plant

growth and crop yield. Soil compaction has been conventionally measured by using a manual

operated cone penetrometer which has certain ergonomically restriction tackled by the

operator, it takes more time and difficult to obtain compaction data. The study aimed to design

and develop a hydraulic system to measure soil compaction for agricultural field, to simulate

soil compaction measuring system using MATLAB Simulink 2018 and to analyze the

simulation output. The modelling and simulation include the hydraulic system used for actuate

the compaction measuring cone penetrometer by considering the vertical force coming from

double acting hydraulic cylinder as variable mass and the soil as a stiffness and damping

property. From the simulation output, the hydraulic performance based on soil compaction

measurement with the parameters such as hydraulic pressure as cone index, depth of operation,

hydraulic torque, and power were analyzed. The time required for the cylinder extension to

insert the cone penetrometer to the soil was 3.3 seconds with the maximum speed of cylinder

extension of 0.3 mm/s. The maximum downward penetration resistance was 0.3 N. The

pressure varies from 24 Pa to 38 Pa during extension of the cylinder and 0 to 15 Pa during

retraction with the maximum flow rate of 3.8 × 10-6 m3/s. The relationship between hydraulic
power and flow rate is directly proportional. Hydraulic torque and flow rate have inversely

proportional relationship.

Keywords:

Agricultural field

Hydraulic System

MATLAB

Modelling

Simulation

Soil Compaction

1. Introduction

Farm mechanization is the main indicator of the

modernizing the agricultural and use of farm machines

that can replace human and animal power in agricultural

processes. Farm machineries are used for land

preparation to the harvesting steps by driving in farm

land in mechanization system. During field operation,

the weight of farm machinery compact the agricultural

soil resulting in increase and decrease of soil bulk

density and porosity, respectively due to the contact

Corresponding author, e-mail: yaredseifu80@gmail.com

https://doi.org/10.20372/ejssdastu:v9.i1.2022.391

with the tires or tracks of tractors (Ungureanu et al.,

2015). Soil compaction is not only caused by farm

machinery, but also by livestock trampling (Chyba et al.,

2014).

The risk of compaction is also dependent on the soil

tillage and crop rotations, soil moisture and working

depth. Soil compaction has been continuously

disregarded in the management of agricultural traffic,

even though it is extremely relevant to maintain the soil

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https://doi.org/10.20372/ejssdastu:v9.i1.2022.....

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

quality of different agro ecosystems (Guimaraes et al.,

2019). Soil compaction is the major problem that affect

the crop production by limiting the potential yield

(Scarparea et al., 2019). Top layer of agricultural soil

compaction by heavy agricultural machinery is one of

the main negative factor which limits plant growth and

crop yield (Benevenute et al., 2020). The compacted soil

is difficult to plough since its strength and draft

resistance is high.

Physical properties of soil play an important role in

determining soil’s suitability for agricultural,

environmental and engineering uses. The supporting

capability; movement, retention and availability of

water and nutrients to plants; ease in penetration of

roots, and flow of heat and air are directly associated

with physical properties of the soil (Phogat et al., 2015).

Soil strength can be measured traditionally using a hand

operated soil cone penetrometer (Guimaraes et al.,

2019). Soil cone index is widely used to assess soil

strength or soil compaction in tillage research. Hence

soil cone penetrometer is an important measuring

instrument to determine soil physical properties.

Excessive compactness is detrimental to maintain a

good root environment. It also reduces penetration of

water and increases runoff and erosion (Mudarisov et

al., 2020). The forces from agricultural equipment cause

soil particles to compact closer and organized into a

smaller volume. As soil particles are compressed

together, the space between particles (pore space) is

reduced, thereby reducing the space available in the soil

for air and water.

Kumar et al. (2019) designed and developed

hydraulically operated mechanical soil cone

penetrometer to measure soil resistance on tillage in the

field up to a maximum cone index value of 2000 kPa.

Tekin et al. (2007) developed a Hydraulic-driven soil

penetrometer for measuring soil compaction in field

conditions. Wang et al. (2020) designed on the basis of

hydraulic principle, which uses tractor hydraulic system

and comprised of driving unit for inserting the probe

into the soil at the desired speed. In mechanized farming

system, farm machineries are used from land

preparation to harvesting by operating in farm land.

Throughout the literature survey conducted, in

Ethiopian there is no research done so far on

hydraulically operated tractor mounted soil compaction

measuring system. In field experiment level, Ethiopian

soil compaction rate and plant/seed growing relation

should be studied for improving the farming system. A

hydraulically operated soil compaction measuring

system which is mounted on tractor in tillage field has

not been studied so far. In global level, many researches

were conducted on related areas.

In the development of separate system for measuring

soil resistance and soil compaction, almost all

researchers were used cone penetrometer. Soil

compaction measuring instrument in field work at

different soil depth and soil profile is crucial in our

country to overcome the aforementioned problems.

Therefore, the study aimed to design and develop a

hydraulic system to measure soil compaction for

agricultural field, to simulate soil compaction

measuring system using MATLAB Simulink and to

analyze the simulation output. From the simulation

output, the hydraulically actuated soil compaction

measurement which consists of parameters such as

hydraulic pressure as cone index, depth of operation,

soil type, hydraulic torque, and power were analyzed.

2. Methodology

The methodology followed in this work is

summurized in Figure 1. The work started by assuming

standard parameters like maximum cone index value

based on agrotechnical requirement. Based on the

assumption, the designing of hydraulic components for

actuating the soil compaction instrument were done.

Then, according to the design, simulation on MATLAB

Simulink was done. The final step was discussion of the

results based on time require for the extension and

retraction of the double acting cylinder for

accomplishment of the soil compaction measurement

with respect to parameters like pressure difference, flow

rate, hydraulic torque, power, etc. This soil testing

instrument can be used in all types of soil except stony

farm land since the hydraulic power damage the cone

penetrometer probe. The simulation input and output

parameters are shown in Figure 2. The results and

discussion are based on time required for the extension

and retraction of the double acting cylinder.

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

Figure 1: Methodology Flowchart

Figure 2: Theoretical frame work of input output parameter

2.1. Operational definition

The system gates hydraulic power from the tractor

hydraulic power unit which contains reservoir and

pump. The hydraulic fluid passing from pump can be

connected to the pressure relief valve for regulating

excess pressure. The double acting cylinder movement

is controlled by a four port three position directional

control valves (4/3DCV). The solid line indicates the

path of the fluid as shown in Figure 3 to Figure 5.

Initially, in ideal work position, the pump pressure line

is connected to the off or to the middle position of

4/3DCV. As shown in Figure 3, the pump pressure

doesn’t pass to the double acting cylinder so that the

fluid return to the tank through the pressure relief valve.

Figure 3: Shutoff position of the hydraulic circuit of the system

Problem identification

Doing simulation using MATLAB Simulink

Extracting data like Hydraulic pressure,

power, Torque etc.

Results discussion and conclusions

Design the methodology of the

work

Designed the components of

hydraulic system

Start Stop

Soil and cone

penetrometer

interaction

Operational Depth

Hydraulic Torque

Hydraulic power

Pressure (cone index)

Hydraulic pressure

Time

A B

P T

Farm land Tank Tank

Tank
Pressure

Relief Valve

Double Acting

Cylinder

Pump
Cone Penetrometer

4/3 DCV

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

Figure 4: Working position of the hydraulic circuit of the system

Figure 5: Retract position of the hydraulic circuit of the system

When the 4/3 DCV allow the fluid coming from the

tank through pump it extends the cylinder road as shown

in Figure 4 and inserts the cone penetrometer into the

soil to measure the soil compaction.

The system in Figure 5 shows when the 4/3 DCV

allow the fluid coming from the tank through pump and

passing at the third position, it retracts the cylinder road

and take out the cone penetrometer from the soil.

2.2. Design and Modelling

The designed model of cone penetrometer was done

based on force coming from the hydraulic double acting

cylinder. The forces model and design acting on the

cone penetrometer at static condition are downward

hydraulic force and upward soil resistance (Figure 6) are

incorporated in design process (Freitag et al., 1970).

Design of Cylinder: Design of hydraulic cylinder is

based on the maximum thrust required to insert the

penetrometer probe into the soil. The maximum thrust

Figure 6: Factors affecting tillage operation

required for the penetrometer can be calculated using

Equation 1 (Perumpral, 1987).

F CI A  (1)

where, F = required thrust, CI = maximum cone index

to be measured, and A= base area of cone in case of cone

penetrometer.

The maximum cone index of soil for which the

system to be designed is assumed to be 3 MPa.

American society of Agricultural and Biological

engineers (ASABE, 1968) adopted the standardization

A B

P T

Farm land

Pressure Line

Tank Tank

Tank
Pressure

Relief Valve

Double Acting

Cylinder

Pump

Cone Penetrometer

4/3 DCV

Pressure gauge

A B

P T

Tank

Tank
Tank

Pump

Pressure

Relief

Valve

4/3 DCV

Pressure

Line

S-Type Strain

gauge load

Cell

Double

Acting

Cylinder

Cone Penetrometer

Farm land

Pressure gauge

Hydraulic force

Upward soil

resistance

Soil physical

properties

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

cone penetrometer as a recommendation for field use

and this is still in use today. These are cone of 323 mm2

base area and 20.27 mm base diameter with a 15.88 mm

diameter probe for loose soil and the second one is a

cone of 130 mm2 base area and 12.83 mm base diameter

with a 9.53 mm diameter probe for firm soil. Using the

first standard, the maximum force required for the

penetrometer can be calculated as: Maximum Force (F)

= 3×106×3.23×10-4 = 967 N.

The piston rod diameter is checked for buckling by

using Euler’s formula (Equation 2). So, Euler’s strut

theory is used to withstand buckling (De Cicco et al.,

2022) .

2 2

( ) 2

64
4

im n

F K L

E
d




 (2)

where, F (buckling load on cylinder rod) = maximum

force applied on cylinder rod × 2, E = young’s modulus

of elasticity (200 GPa for steel EN8), d = diameter of

cylinder rod, L = length of cylinder rod (taking 200 mm)

and K = constant, 2 for one end fixed and another end

free.

2 2

( ) 2 9

967 2 64
4 0.008418 8

0.2
.42

200 1i
m n

d mm m
 

 
  



The aavailable size of cylinder rod is 32 mm with

cylinder bore of 100 mm. Hence, the cylinder rod is safe

for buckling. As a result, Equation 3 can be used to find

the smallest diameter of cylinder rod that can withstand

the load (De Cicco et al., 2022).

F
d


 (3)

where, σ is maximum yield stress of cylinder road

material (380 MPa) and taking factor of safety = 2

4 967 2
6.48

380
d mm



 
 



Available size of cylinder rod is 32 mm. Hence, the

cylinder can resist the load.

The pressure required to developed thrust on the

annular side of the cylinder can be calculated using

Equation 4 (Watton, 2007).

2 2
( )

4
c r

F F
P

A
d d


 



(4)

where, P is pressure coming from hydraulic system, dc

and dr are cylinder diameter and cylinder road diameter,

respectively.

2 2

967
1.3724

(100 32 )
4

P bar

d


 



Relief valve pressure should be adjusted at a pressure

>25% than that required to give a thrust, considering the

pressure drop in the pipes and other components. The

bore side and annual side in m2 of the cylinder are

calculated using Equation 5 and 6, respectively (Watton,

2007).

Full bore area, 2( )
4

c
A d


 (5)

2 2 2
(100 ) 7854 78.54

4
A mm cm


  

Annulus area, 2 2( ) ( )
4

c r
A a A d d


    (6)

2 2 2 2
(100 32 ) 7050 70.50

4
A mm cm


   

The piston velocity should be 3 cm/s to penetrate

into soil to meet the standard cone penetration velocity

as per ASAE S313.3.

When piston rod is extending Piston velocity, V can

be calculated using Equation 7 (Mirzaliev et al., 2020):

3 / 30 /E E
Q q

V cm s mm s
A A a

   


(7)

where, QE = flow into full bore end of cylinder when

extending in m3/s, qE = flow from annulus end of

cylinder when extending

Q A V  (8)

3 3
78.54 3 235.62 / 0.01414 / 14. 14QE cm s m min lpm  

  Eq A a V   (9)
3 3

70.5 3 211.5 / 0.1269 / 12.69
E

q cm s m min lpm    

Figure 7: (a) Cylinder under extended condition (b)

Cylinder under retracted condition.

VR (b) (a)

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

When piston rod is retracted, piston velocity, V, can be

calculated using Equation 10 (Watton, 2009):

R R
Q q

V
A A a

 


(10)

where, QR= flow into full bore end of cylinder when

retracting in m3/s, qR= flow from annulus end of cylinder

when retracting in m3/s = QE =235.62 cm
3/s

235.62
3.34 /

70.5
V m s 

3 3
78.54 3.34 262.324 / 0.01574 / 15.74

R
Q A V cm s m min lpm      

3 3
78.54 3.34 262.324 / 0.01574 / 15.74

R
Q A V cm s m min lpm      

Table 1: Design summary for the double acting cylinder

S. No. Parameters Value

1 Cylinder diameter 100 mm

2 Rod diameter 32 mm

3 Stroke length 200 mm

4 Stroke speed 30 mm/s

5 Return stroke speed 33.4 mm/s

6 Oil flow required in forward

stroke

14.14 lpm

7 Oil flow required in return

stroke

15.74 lpm

8 Full bore area 7854 mm2

9 Annual area 7050 mm2

2.3. Modeling of the soil compaction measuring

system

The MATLAB Simulink of hydraulic system model

in Figure 6 includes a tractor auxiliary hydraulic system

which includes hydraulic oil, hydraulic pump for crating

pressure and velocity, hydraulic motor for creating

mechanical rotation. The system get power from the

hydraulic reference unit passing through pump. The

pressure relief valve used for regulating excess pressure

and save the four by three directional pressure control

valve. Manual operated four port three position

directional control valve directs the directional

movement of the fluid as well as stops the operation.

The double-acting cylinder create linear movement and

inserting cone penetrometer into the soil for measuring

the vertical soil pressure.

A real system gates hydraulic power from the tractor

hydraulic power unit, which contains a reservoir and

pump. The pressure applied from the cylinder is

modelled as a variable mass and the soil is modelled as

solid particle which contains its own spring and

damping property. The model input parameters are the

design parameters which are summarized in Table 1.

Figure 8: MATLAB Simulink model of the hydraulic system

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

3. Results and discussion

The results of the hydraulic cylinder simulation

outputs which include time required for the cylinder

extension and retraction, pressure variation during

cylinder extension and retraction, soil compaction

resistance in a form of damper and soil stiffness in a

form of spring property, the flow rate through pump to

hydraulic cylinder, power and torque are presented and

discussed in this section. The simulation output graph

(Figure 9) represents a double-acting hydraulic cylinder

output parameter during the extension of cylinder. The

model of the cylinder is constructed from the

translational hydro-mechanical converter and

translational hard stop blocks. The rod motion is limited

with the mechanical translational hard stop block. The

time required for the cylinder extension to insert the

cone penetrometer to the soil is 3.3 seconds and the

maximum speed of cylinder extension is 0.3 mm/s.

The simulation output graph (Figure 10) shows the

pressure variation through pressure line and returning

line. Connections A and B are hydraulic conserving

ports. Port A is connected to converter A and port B is

connected to converter B.

Figure 9: a) hydraulic cylinder speed with respect to simulation time and b) single stroke distance with respect to

simulation time

Figure 10: a) pressure variation in hydraulic cylinder at port A with respect to simulation time and b) Port B with

respect to simulation time

Figure 11: Soil compaction resistance force with respect to simulation time

a) b)

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

The block directionality is adjustable and can be

controlled with the cylinder orientation parameter. The

result shows in the first 3 seconds the pressure in port A

varies within 24 Pa to 38 Pa and pressure in port B varies

within 0 to 15 Pa.

The graph in Figure 11 shows soil compaction

resistance force with respect to simulation time based the

model of soil as solid variable mass. The result indicates

that the maximum soil resistance force is 0.03 N.

The block in model has one mechanical translational

conserving port and one physical signal input

representing the soil as mass. The block positive

direction is from its port to the reference point. This

means that the inertia force is positive if mass is

accelerated in positive direction. Based on this, the

graph output in Figure 12 shows the maximum

downward penetration resistance force of 0.3 N with the

maximum penetration speed of 0.032 mm/s.

The flow rate of oil from the pump used to create

linear motion for the cylinder road is plotted in Figure

13. From the plot, the maximum flow rate is 3.8×10-6

m3/s. The property of the flow rate during the cylinder

extension is increasing for the first half second and start

to decrease up to 3 minutes during the cone

penetrometer start to penetrate the soil. During

penetration, again it reaches to maximum flow rate and

finishes the extension of the road and starts retracting

the cylinder road.

The hydraulic power graph during the soil

compaction measurement model shown in Figure 14

indicates the maximum hydraulic power required to

extend and retraction the hydraulic cylinder to inserts

and take out the cone penetrometer is 1.9 kW. The

relationship between hydraulic power and flow rate is

directly proportion as shown in Figure 13 and 14.

Figure 12: a) Translational spring force with respect to simulation time and b) speed require for insert the cone

penetrometer in to soil with respect to simulation time

Figure 13: Pump flow rate with respect to time

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

Figure 14: Pump hydraulic power with respect to simulation time

The hydraulic torque graph during the soil

compaction measurement model is shown in Figure 15.

It indicates the maximum torque required to extend and

retract the hydraulic cylinder and to inserts and take out

the cone penetrometer is 0.0502045 Nm. The minimum

torque required to extend and retract the hydraulic

cylinder, and to inserts and take out the cone

penetrometer is 0.05020362 Nm. The relationship

between hydraulic torque and flow rate is inversely

proportional as shown in Figure 13 and 15.

A model of pump with constant volumetric

displacement that supplies mechanical energy to a

hydraulic system are susceptible for losses due to flow

leakage and friction torque. The pump may operate in

both the forward and reverse directions depending on

the rotation of the shaft. The simulation output graph is

shown in Figure 16. The result shows the pressure

decreases from 38.05 Pa in a few seconds to 37.90 Pa

and start increasing and reaches 38 Pa. When the cone

Figure 15: Pump hydraulic torque with respect to simulation time

Figure 16: Pump pressure difference during extension and retraction the hydraulic cylinder with respect to simulation

time.

Yared Seifua et al. Ethiop.J.Sci.Sustain.Dev., Vol. 9(1), 2022

penetrometer come into contact to the soil, the pressure

decreases to minimum pressure of 37.8 Pa. During the

interaction of soil and cone penetrometer, the pressure

variation graph shows sine wave and finishes the first

cylinder extension cycle. In the cycle, the pressure

variation is from 37.87 Pa to 38.13 Pa.

4. Conclusion

In this study an attempt has been made to develop a

hydraulically operated soil compaction measurement

system. MATLAB Simulink 2018 is used to model and

simulate parameters like vertical force as a variable

mass and the soil as a stiffness and damping property.

The cone index, which is the resisting pressure of soil,

of 3 MPa is used for mathematical analysis. The

maximum hydraulic pressure used for extend and retract

the double acting cylinder for the purpose of inserting

and take out the cone penetrometer is 38.05 Pa. The

designed system can measure up to maximum cone

index on 3 MPa but for this selected soil parameters the

maximum pressure required is 38.05 Pa. From Simulink

simulation the time required for the cylinder extension

to insert the cone penetrometer to the soil is 3.3 seconds

with the maximum speed of cylinder extension of 0.3

mm/s. The maximum downward penetration resistance

force of 0.3 N and soil compaction resistance force

based the model of soil as solid variable mass the

maximum soil resistance force is 0.03 N. The maximum

flow rate is 3.8×10-6 m3/s. Flow rate is directly

proportion with hydraulic power and inversely

proportional with torque.

Acknowledgment

This research work is sponsored by Dire Dawa

University. The authors would like to thank Adama

Science and Technology University for their support in

a form of facilitating PhD scholarship for the student.

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