1. SEMI –ACTIVE SUSPENSION SYSTEM
Presented By –
Rohit Agarwal
Pulkit Jain
11/13/2018

2. ABOUT US Rohit Agarwal Alma-Mater: VIT University (2010-2013)
ARAI Academy ( )
Academic achievement
Merit certificates in all the 3 years of B.tech
Participated in BAJA SAE 2013 in which the team stood 4th
Projects Completed:
Research paper published on Simulation of Drive Train Comprising CVT in IJET
Languages Known:
English, Hindi, Bengali
Extra-Curricular:
A grade in A level NCC
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3. Pulkit Jain Alma-Mater: VIT University (2010-2013)
ARAI Academy ( )
Research Experience:
Reviewed Research papers on Alternative Fuels
Projects Completed:
Design and Simulation of Epicyclic Gear Train
Numerical Simulation of Spark Ignition Engine Using
Wiebe Function
Languages Known:
English, Hindi, Telugu, German,
Extra-Curricular:
National Level Table Tennis
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4. FLOW OF CONTENT INTRODUCTION HISTORY CLASSIFICATION OF SUSPENSION
MATHEMATICAL MODELLING
EQUATIONS
SIMULINK MODEL
RESULTS
CONCLUSIONS
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5. INTRODUCTION Suspension includes springs, shock absorbers and linkages
Strut
Suspension includes springs, shock absorbers and linkages
Supports the weight
Provides a smooth ride
Help in cornering
Prevents excessive squat and dive
Isolate the passenger compartment from road vibrations
Link
Tyre
Chassis
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6. VEHICLE LAYOUT
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7. HISTORY Leaf springs - Obadiah Elliot 1804 1863
Patent for coil spring - R. Tredwell
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8. HISTORY Contd. Two-Seat vehicle with Dampers - William Brush
1906
Two-Seat vehicle with Dampers - William Brush
1930
Coil spring front suspension (Independent ) - General Motors
MacPherson struts.
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9. CLASSIFICATION Axle Based Spring Based Technology Based
Non Independent
Independent
Spring Based
Leaf Spring
Coil Spring
Technology Based
Passive
Semi Active
MR Suspension
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10. AXLE BASED 1. Non-independent suspension
Both wheel attached to the same solid axle.
One wheel upward movement causes a slight tilt of the other wheel.
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11. Contd. 2. Independent suspension Axles are independent
Allows one wheel to move up and down
Minimal effect to the other wheel
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12. SPRING BASED Leaf spring Commonly used in heavy vehicle
Acts as a linkage for holding the axle in position
Riding comfort is not good
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13. Contd. 2. Coil spring Most common type in now days cars
Provide good ride comfort
Absorbs large amount of energy then leaf spring
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14. TECHNOLOGY BASED Passive suspension Basic type of suspension
No external source of energy
Components:
Linkages
Springs
Dampers
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15. Contd. Linkages Springs Movable lever
Connects the steering knuckle to the vehicle’s body or frame.
Springs
Supports the weight of the vehicle
Permits the control arm and wheel to move up and down.
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16. Contd. Dampers Helps in vibration damping
Piston moves up and down due to relative motion of chassis and axle
Oil flow from one cavity to other through holes
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17. Contd.
Two stroke
Compression stroke
Extension stroke
Friction between oil and piston wall form the damping force
Damping force is proportional to velocity
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18. SEMI ACTIVE SUSPENSION (SAS)
Consists of a spring, damper and linkages
The value of the damper coefficient Cs can be controlled and updated.
This changes the stiffness characteristic of the suspension system
Required ride and handling can be obtained
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19. SAS Contd. Magneto rheological damper
A MRD is not very different from a conventional viscous damper
The key difference is the magneto rheological (MR) oil and the presence of a solenoid
MR oil contains micron-sized ferromagnetic particles in suspension
Due to the polarising magnetic field, particles tend to form chains, which modifies the value of the oil yield stress.
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20. Contd. Rheological properties of oil changes Hence by controlling the
solenoid current, continuously
variable damping can be produced
The energy requirements are extremely low
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21. PASSIVE V/S SEMI ACTIVE
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22. MATHEMATICAL MODELLING
Quarter car model (passive)
Simple way of representing one wheel motion of vehicle
Contain :
Sprung mass(ms )
Unsprung mass(mu)
Tyre represented by spring of stiffness ku
road
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23. Contd. Quarter car model (semi active)
The value of Cs is varied by using PID controller
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24. PID CONTROLLER A proportional-integral-derivative controller
Controller calculates an "error" value
These values can be interpreted in terms of time:
P depends on the present error,
I on the accumulation of past errors, and
D is a prediction of future errors, based on current rate of change.
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25. EQUATIONS Spring force ks (xs - xu) Damper force Cs(x’s – x’u)
Tyre force ku(xu − y)
road
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Ref.-

26. Vehicle Dynamics:Theory and Application by Reza N. Jazar
Contd.
Finally we get
SPRUNG MASS
ms x”s = −ks(xs − xu) − Cs(x’ s – x’u)
UNSPRUNG MASS
muxu” = ks(xs − xu) + Cs(x’s– x’u) − ku(xu − y)
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Vehicle Dynamics:Theory and Application by Reza N. Jazar

27. SIMULINK MODEL
PASSIVE
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28. Contd.
SEMI ACTIVE
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29. INPUT PARAMETERS Parameter Symbol Value Sprung mass ms 375 kg
Unsprung mass mu
75 kg
Spring stiffness ks
3500 N/m
Damping coef. Cs
500 N s /m
Tyre stiffness ku
N/m
Road input
step function
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Ref. -

30. Ref. - boseindia.com/information/ Suspension System
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Ref. - boseindia.com/information/ Suspension System

31. RESULT Passive suspension(disp.(m)vs time(sec)) Semi active suspension
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32. FUTURE PROSPECTS Simulink model based on skyhook model Driver comfort
To Determine Frequency
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33. REFERENCES Semi-active Suspension Control By Guglielmino et tal.
Vehicle Dynamics : Theory and Application by Reza N. Jazar
Semi-active suspension control design for vehicles by sergio et tal.
Race Car Vehicle Dynamics
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34. THANK YOU
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