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 )

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.

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.

SUSPENSION SYSTEM LAYOUT

ACTIVE SUSPENSION LAYOUT

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.

•

IMPORTANT PROPERTIESSpring 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.

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.

VIBRATION MODES OF THE SUSPENSION ELEMENTS

• SUSPENSION SPRINGS

Suspension Springs are the suspension system's primary line of defense

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.

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.

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

Where

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

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.

DISADVANTAGES

•Need for a large external power source

•Complex control algorithms

•Complex closed-loop control systems.

•Requirement of fast-acting devices

•Increased cost

•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

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.

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