ESP

Electronic Stability Programs

Aim and Objectives

Aim:• To give an introduction to ESP (Electronic Stability Program) on light vehicles.

Objectives:At the end of the session, students should be able to: • Identify why ESP systems are used on vehicles• Acknowledge how ESP Systems prevent the vehicle from spinning during

heavy braking and steering• Locate and describe the operation of the Yaw sensor• Identify the direction of the Z axis

What is ESP?

• ESP stands for Electronic Stability Program

• It is used on vehicles to

prevent “spinning” during heavy braking and steering, as shown in the image on the left

How Does It Do It…

ESP utilises w/speed sensors to monitor the road wheels, as well as a yaw speed sensor to detect its level of movement through the z axis (spinning) and a steering wheel angle sensor. It also uses traction control and anti-lock braking systems, it can’t work on its own. •Traction Control is used in order to drop acceleration from the wheel that is deemed to be slipping. •ESP also uses ABS to activate the brakes on individual wheels at the required level to prevent the driver from losing control.

Under and over steer

• Understeer occurs when you go around a corner much too fast and the front wheels don’t have enough traction. As a result you end up going forward instead of turning.

• Oversteer is the opposite, the car turns more than the driver intended to causing the rear wheels to slide and the car to spin.

• Understeer is common on front wheel drive cars

• Oversteer is common on rear wheel drive cars

Yaw describes the rotation of the car about the z-axis. This is known as the yaw angle. It is the angle between a line pointing in the direction the car is moving and the car's x-axis (which is the direction the car is pointed).

What is the Z Axis?

Yaw angle

Sensors used…

Wheel speed sensor monitors the rotational speed of the road wheels, and detects when the vehicle is de-accelerating (slipping)

Yaw Speed Sensor, detects rotation around the z axis (spinning)

Steering angle sensor measures the angle of the steering wheel, to monitor what direction the driver wishes to steer

Location of major components

• Imagine this is facing you! Naturally you would brake and swerve!!

How does ESP work?

• ESP Will monitor your steering angle and the direction around the Z axis (yaw angle)

How does ESP work?

• As you begin to skid the hydralic modulator will adjust the brake pressure to ensure that you make that change of direction safely!

How does ESP work?

• The danger here is that the vehicle will over steer and “spin”

How does ESP work?

• The ESP system will fluctuate the brake pressure, and prevent movement around the Z axis, keeping the vehicle in a straight line.

How does ESP work?

Have we:

• Identified why ESP systems are used on vehicles?

• Acknowledged how ESP Systems prevent the vehicle from spinning during heavy braking and steering?

• Located and can describe the operation of the Yaw sensor?

• Identified the direction of the Z axis?

Summary