knowledge about suspension system

1. MAJOR ASSIGNMENT
SUBJECT -: I C ENGINE
TOPIC-: INTELLGENT ACTIVE SUSPENSION SYSTEM FOR TWO WHEELER
SUBMITTED TO - SUBMITTED BY.-
MR.AMARDEEP SIR
ASSIST. PROF. ME. DEPT RAMRATAN NMALAV
UID -: K10888
BRANCH -:ME (6TH )

2. WHAT IS AN ACTIVE SUSPENSION
SYSTEM
• The Active or adaptive suspension is an automotive
technology that controls the vertical movement of
the wheels with an onboard system rather than the
movement being determined entirely by the road
surface.
• It has two main functionalities, one is to isolate the
vehicle body with its passengers from external
disturbance inputs which mainly come from irregular
road surfaces.
• The other is to maintain a firm contact between the
road and the tyres to provide guidance along the
track.

3. FUNCTION OF SUSPENSION
 In active suspension systems, it employs springs as
the main form of support, however the dampers can
usually be controlled.
 A active suspension has the ability to change the
damping characteristics of the shock absorbers
without any use of actuators.
 The basic function of the vehicle suspension is to
provide comfort to passengers, maximize the friction
between the tyres and the road surface and provide
steering stability with good handling.

4. SUSPENSION SYSTEM LAYOUT

5. ACTIVE SUSPENSION LAYOUT

6. SHOCK ABSORBERS (DAMPERS)
•It is a device that controls unwanted spring motion through a
process known as dampering.
•Shock Absorbers slow down and reduce the magnitude of
vibratory motions by turning energy of suspension movement into
energy that can be dissipated through hydraulics.

7. IMPORTANT PROPERTIES
Spring rate
• The spring rate (or suspension rate) is a component in setting
the vehicle's ride height or its location in the suspension
stroke. Vehicles which carry heavy loads will often have
heavier springs to compensate for the additional weight that
would otherwise collapse a vehicle to the bottom of its travel
(stroke).
• Springs that are too hard or too soft cause the suspension to
become ineffective because they fail to properly isolate the
vehicle from the road.
• Vehicles that commonly experience suspension loads heavier
than normal have heavy or hard springs with a spring rate
close to the upper limit for that vehicle's weight.

8. DAMPING
 Damping is the control of motion or oscillation, as seen with
the use of hydraulic gates and valves in a vehicles shock
absorber. This may also vary, intentionally or unintentionally.
Like spring rate, the optimal damping for comfort may be less
than for control.
ROLL CENTER HEIGHT
• This is important to body roll and to front to rear roll
stiffness distribution. However, the roll stiffness
distribution in most cars is set more by the antiroll
bars than the RCH. The height of the roll center is related
to the amount of jacking forces experienced.

9. VIBRATION MODES OF THE
SUSPENSION ELEMENTS
• SUSPENSION SPRINGS
Suspension Springs are the suspension system's primary line of defense

10. IMPORTANT POINTS
• These variables within the surface of the street or
the backcountry road send force up through the
wheels. .
• The suspension spring's task is to absorb this
power and carry your wheels back to a condition
of equilibrium.
• You will find several standard types of Suspension
Springs used on contemporary vehicles: Leaf
Springs, Coil Springs, Torsion Bars, and Air
Springs.

11. MATHEMATICAL MODEL OF ACTIVE
SUSPENSION SYSTEM
 The model can be used for determining the
adjustable arm’s angle for which the system
produces a required force.
 The trailing arm joins the unsprung mass (wheel
unit) to the sprung mass (the car body) and provides
a connection to the primary spring and damper. The
adjustable arm defines the position at which the
secondary spring is attached to the suspension
system.

13. Where
For small suspension deflections, it is assumed that
the point at which the secondary spring is attached to
the suspension system moves along a circular
trajectory

14. Where

15. ADVANTAGES
Improved Steering, Handling and Braking
•In a rigid suspension, if one wheel jogs or bounces, the entire
axle tilts, causing the opposing wheel to tip in or out at the top,
no longer rolling straight ahead, an effect called "bump steer".
•Rigid axles are also less responsive on turns and vehicles
carrying heavy loads are subject to instability called "shimmy",
caused by forces translated across the axle from wheel to wheel.
•During hard braking, solid beam suspension can cause the front
of the vehicle to nose dive and twist. Independent front
suspension (IFS) corrects or vastly improves all of these effects
by allowing wheels on the same axle to respond

16. Ride Quality
•Ride quality is a concern that has evolved with our culture's
increasing dependency on automobiles for recreational and
commuter travel.
•Overall ride quality, or how comfortable a car feels to ride in or
drive, is measured by a combination of factors, including noise
and vibration, the translation of bumpy road surface to
passengers, the smoothness of the car's steering and how well a
car handles and corners.
•Active suspension system solves some of these problems by
de-coupling the front wheels, improving overall stability and
creating isolation between the suspension and the vehicle
chassis.

17. DISADVANTAGES
•Need for a large external power source
•Complex control algorithms
•Complex closed-loop control systems.
•Requirement of fast-acting devices
•Increased cost

18. •In the case of active suspension system, as in any
other innovations of automotive technology, today's
innovation is tomorrow's standard feature.
• Inspite of its high initial cost, let us expect to see
them in the Indian roads soon. The trickle-down
effect will take some time, but it'll happen and when
such a time comes we can expect much lesser
accidents, less fatalities and more comfort in driving
the roads.
Conclusion

19. REFRENCES
[1] Genta, G., Morello, L. (2009). The Automotive Chassis, Vol. 2: System Design,
Mechanical Engineering Series, Springer, DOI:10.1007/978-1-4020-8675-5.
[2] Karnoop, D. (1986). Theoretical limitations in active vehicle suspension.
International Journal of Vehicle Mechanics and Mobility, vol. 15, no. 1, p. 41-54,
DOI:10.1080/00423118608968839.
[3] Herdrick, J.K., Batsuen, T. (1990). Invariant properties of automotive suspension.
Proceedings of the institution of mechanical engineers, Part D: Journal of Automobile
Engineering, vol. 204, no. 1, p. 21-27, DOI:10.1243/PIME_PROC_1990_204_128_0.
[4] Hrovat, D. (1993). Application of optimal control to advance automotive suspension
design. Transaction of ASME, Journal of Dynamics Systems, Measurement And Control,
vol. 115, p. 328-342, DOI: DOI:10.1115/1.2899073.