vehical skid infomation

2. 1. INTRODUCTION
Vehicle skid can be defined as the loss of traction between a vehicle’s tyres and the
road surface due to the forces acting on the vehicle. Most skids are caused by driver
error, although only about 15% of accidents are the direct result of a vehicle skidding.
To counter these skids and to prevent accidents from hapenning,Vehicle Skid
Control(VSC) is incorporated in the vehicle.
2. CAUSES
The main causes of skidding are as follows:
a) Harsh or sudden acceleration.
b) Excessive or sudden braking.
c) Coarse or jerky steering movements.
d) Over steer and understeer
3. TYPES OF SKID
The main types of skid that a driver could encounter on the public highway fall into three
Categories.
1) The front wheel skid.
2) The rear wheel skid .
3) The four wheel skid . .

3. 3.1. The Front Wheel Skid
1:FRONT WHEEL SKID
3.1.1.Characteristics
The car tends to take a course outside of the expected course that
the driver has steered (understeer); see figure 1.

4. 3.2.1. Characteristics
The rear of vehicle swings out of line and gives the impression of trying to
overtake the front (over steer); see figure 2.

5. All four wheels have locked up and the vehicle is sliding in the direction
that the forward momentum is carrying it, with no directional control; see figure 3.
Both front and rear wheel skids, if unchecked sufficiently early, can develop into
four wheel skids.
3.3.1. Characteristics

6. Stability control systems or skid control systems with
names like StabiliTrak, Dynamic Stability Control,
Stability Management, and Vehicle Skid Control are the
latest advancement in vehicle safety. Regardless of the
different names, they all perform the same task – to
sense the onset of traction loss and keep the driver on
track.
Luxury cars, such as the Mercedes Benzes, BMW,
Lexus, etc. now sold in India, have stability systems
installed that are designed to remove over steer or
understeer.

7. The Vehicle Skid Control (VSC) is made possible by the combination of different
electronic and mechanical components. Some of the components are those used in
Anti-lock Braking System (ABS), and an electronically controlled engine throttle, as well
as a dedicated computer and sensors, providing information to the VSC system. These
include:
•Yaw rate sensor.
•G-sensor.
•Steering angle sensor.
•Electronic throttle control.
•Slip indicator.
•Computer

8. The heart of all these systems is a central processor that takes information from a
number of sensors, and then determines whether the car is in a stable or unstable
state. By combining the data's from ABS sensors (for wheel speed), steering angle
sensors, yaw sensors (measuring the amount a car fishtails, or rotates around its
vertical center axis), and lateral force sensors (measuring the amount of sideways g-
force generated by the car), the central processing unit can actually detect when a
vehicle is behaving in a way contrary to how the driver intends. VSC also includes a
slip indicator with a warning sound and light to alert the driver that the tyres are about
to exceed the grip limit.
control during emergency braking on wet and slippery roads whereas VSC
is intended to help a driver maintain the intended direction of travel, even when
the brakes are not applied.

9. 1. Monitors each wheel independently maximizing the performance of the car.
2. Increases comfort, both physical and psychological
3. Improves safety aspects of the car and the driver.
4. Enhances the ability to dodge a renegade object in its pathways.
5. Helps save money long term.
2. Overdependence.
1. High initial costs.
3. Not perfect.
4. Repairing cost may be high

10. Driving has become more and more dangerous with the
ever increasing population of man and vehicles. It is estimated
that 25% of all accidents are caused by driver distractions.
Vehicle Skid Control would not, in anyway, eliminate all road
accident; however it would lower the percentage of crashes
there by lowering the number of fatalities.