How active safety systems work
An active safety system is a term used to describe features of a car such as ABS, Traction Control and Power Assisted Steering. These features are designed to improve safety while you are driving the vehicle. They are used to maintain the stability of the vehicle while undertaking regular driving tasks such as braking, accelerating and steering. Active Safety Systems are constantly being improved by vehicle manufacturers and in this article, we’ll take a look how active safety systems work.
What are active safety systems?
You might not have heard of Active Safety Systems before. But you probably have heard of things like ABS (Anti-lock brake system) or power steering. Collectively these popular car safety features are named Active Safety Systems. With vehicle safety coming under constant scrutiny, manufacturer’s are investing more into developing Active Safety Systems. It is generally believed that Active Safety Systems will play an increasing role in collision avoidance and mitigation in the future.
BLIS – Blind Spot Information System
The Blind Spot Information System was developed by Volvo. Volvo’s parent company the Ford motor group have continued to develop the technology. BLIS is now featured on cars within their Ford, Mercury and Lincoln brands. It is a sensor that is used to detect other vehicles to the side and rear of the car. Drivers are alerted with visual, audio or touch based notifications. Touch based notifications can include things like a vibration in the seat or steering wheel. Some blind spot monitors also feature ‘Cross Traffic Alert’ which notifies drivers if traffic is approaching them from the side. This is useful when backing out of parking spaces.
Here’s a handy video from Ford which describes how BLIS works.
Anti-lock Braking System
You’ll notice that most, if not all, modern cars are fitted with ABS. An Anti-lock Braking System offers drivers some control over the car when braking harshly. It’s designed to stop wheels from locking up during an emergency brake, giving drivers back control over their steering. It’s an electric device on the hydraulics in the brake system. When the foot brake pedal is applied each wheel begins to slow and come to a stop. When braking harshly the wheels can lock entirely. This would mean the driver could no longer steer the vehicle away from the hazard. ABS detects when the wheel is about to lock and releases the brake on that wheel only. When the wheel begins to rotate again the system will re-apply the brake.
When the ABS is activated you must continue to brake with maximum pressure throughout. Many people worry when the ABS light comes on the dashboard. The vibration in the brake pedal can cause some people to reduce the pressure on the foot pedal. ABS may result in increased stopping time/distance. It doesn’t guarantee that the car won’t skid but it does help reduce the risk.
Emergency Brake Assist
New cars also feature Emergency Brake Assist which is known as EB or EBA. This safety feature increases the pressure on the brake pedal in an emergency. It came about as a result of research conducted in 2002 by Mercedes Benz. The study showed that 90% of drivers did not apply enough force to the brake pedal in the event of an emergency. If the brake pedal is not fully applied, the system overrides and fully applies the brakes to ensure the car stops as soon as possible.
Traction Control Systems
Traction Control (TCS) is designed to prevent the car from skidding or slipping during acceleration. On occasion, the power from the accelerator to your wheels will be higher than the available grip in the tyre. Or to be technical, it’s when the throttle input and engine torque are mismatched to road surface conditions. This is commonly known as a wheel spin. Unless you are a ‘boy racer’ a wheel spin isn’t the desired outcome of accelerating. So the Traction Control System will monitor each wheel for the excess spin. If a wheel is spinning too fast for the road surface it will apply a brake to the individual wheel. Some systems will also reduce the engine power to the wheel.
A common eventuality for wheel spinning is where one tyre grips the road as normal and the other slips on ice. The TCS makes maximum use of the tyre grip. A warning light will appear on the dashboard when traction control is engaged.
If traction control is engaged when you pull away, reduce pressure on the accelerator to regain full steering control.
Electronic Stability Programmes (ESP)
Incorporating Anti-lock braking (detailed above) and traction control (detailed above) the Electronic Stability Program regulates the vehicle if it is being driven beyond its physical capabilities. Each manufacturer will have their own settings for the ESP. It’s worth checking your vehicle handbook for details on your model’s individual settings.
Broadly speaking ESP has a sensor on each wheel which works in conjunction with a yaw sensor. A yaw sensor is a device that measures the cars velocity around its vertical axis. A further sensor is placed on the steering column which monitors the drivers intended direction. Each sensor talks to each other and if the wheels are not pointing in the right direction according to the sensor on the steering column. If any of these sensors detect that the car is not moving in the direction intended then the system intervenes.
It works by applying the brakes to individual wheels in order to correct the alignment of the vehicle fixing over-steer or under-steer.
How do I know if my car has Active Safety Systems?
When you start your engine your active safety systems will engage. You’ll notice some lights flash up on the dashboard. These represent all of the active safety systems in place on the vehicle. If you’re not sure what these mean you can check your vehicle manual or even Google your model of vehicle to discover what active safety systems are fitted to your vehicle.
Active Safety Systems will play a large part in increasing vehicle safety over the coming years. As a quick look guide here is what each safety system does. ABS prevents the wheels from locking up when you brake too hard. Traction control prevents wheel spinning if you accelerate too harshly for the road surface. ESP helps to reduce over steer or under steer preventing skidding if you steer too sharply. Blind Spot Information Systems are there to help detect other vehicles to avoid collisions.
Even if your car is kitted out with every safety feature known to man you should always drive carefully and not rely on these systems to keep you and other road users out of harm. If one of these safety features are activated you should assess your driving and what has led to the need for the intervention of the safety system to avoid further accidents.