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Collision avoidance with radar

Collision avoidance systems: How to prevent accidents with radar

Learn how a collision avoidance system & collision detection sensors work.

The aim of a collision avoidance system is to prevent collision-related accidents and damages. Today, these systems for collision detection are not only found in cars in the form of distance warning systems, lane change assistants and emergency braking assistants. Trucks, tractors, construction vehicles, cranes, robots and drones also rely on reliable anti-collision sensors for obstacle detection in order to avoid damage and accidents caused by collisions with people or obstacles. Radar is particularly suitable for collision avoidance. The reason: The weather-independent radar sensors detect obstacles even in rain or snow, wind, poor visibility, extreme temperatures, water vapor, fog or dirt.

How collision detection works

A collision avoidance system detects dangerous situations before an accident occurs

Collision warning system for trucks & cars

What is a collision avoidance system?

A collision avoidance or collision warning system is a safety device for various types of vehicles, aircraft or ships. It is intended to prevent accidents by pointing out critical situations or intervening in vehicle steering before a collision occurs. Obstacle avoidance and collision detection systems are used in cars, trucks, tractors, construction vehicles, mobile robots, airplanes and drones.

Typical collision warning sensors

Different collision warning sensors and technologies are used to safeguard against collision-related damages and accidents. This includes not only lasers (LIDAR), ultrasound and radar sensors, but also acceleration sensors, cameras and navigation systems (SLAM, GPS). They generate important data that sheds light on potential obstacles. They also record the position and direction of movement of the vehicle. This information is then further processed for collision avoidance so that the system can intervene in time.

How a collision avoidance system works

So how does an anti collision system work? If a critical situation with the potential for an accident is detected, the collision avoidance system becomes active in two different ways: First, it can alert the driving staff or supervisor to a danger via an alarm tone, a flashing light or a vibrating steering wheel (collision warning). Second, the system can intervene directly, for example by automatically braking the vehicle or changing the vehicle's course to circumvent an obstacle (obstacle avoidance). If necessary, the collision prevention system can even cancel the actions of the driving personnel.

Radar sensors for collision avoidance

Collision warning radar sensors are very reliable and detect obstacles even in poor visibility

Collision avoidance with radar: How it works

The most common radar type used for collison avoidance systems is the FMCW radar. To identify possible obstacles, the radar detects the position of static or moving objects in the radar beamwidth via distance measurement. When the radar sensor detects an obstacle within defined distance values, it activates a multi-stage safety process. Vehicles with radar-based collision detection usually have at least two safety zones defined by threshold values: the warning zone and the protection zone.

If there is an obstacle in the warning zone, the vehicle must reduce its speed in order to be able to stop in time. If the radar sensor detects an obstacle in the protection zone, the vehicle must come to a standstill immediately to safely prevent a collision. This happens either automatically or via a warning message to the driving staff.

Collision warning sensors: Advantages of radar

Compared to other collision avoidance sensors such as laser sensors (lidars), ultrasound sensors and vision systems (cameras), radar sensors have certain advantages when it comes to avoiding collision-related accidents. With a radar sensor, for example, the wavelength is significantly higher than with a laser or lidar sensor, so that fine dust particles or water vapor do not disturb the radar signal. This is why a radar sensor can detect obstacles even in difficult conditions such as dirt, dust, rain, snow, steam or smoke.

In addition, in contrast to ultrasonic sensors, the speed of propagation of radar sensors does not depend on temperature, pressure or humidity. This makes reliable measurements for collision warning possible even in adverse environments and outdoors. Even dirt on the lens does not affect the radar collision detection. In addition, compared to lidar sensors or vision systems, the radar sensor has neither moving parts nor sensitive optics. Radar technology therefore requires significantly less maintenance and is more robust.

Comparison of anti collision sensors

In the following graphic you will find a comparison of the performance of different sensor technologies – vision system, ultrasonic sensor, laser sensor and radar sensor – for collision avoidance and obstacle detection:

Collision avoidance





Obstacle detection with dirt, smoke, fog, water drops, snow

Robustness against vibrations, extrem temperatures, difficult light conditions, pressure variations

Wide detection range

Low-maintenance sensor

Acquisition cost

Where radar is used for collision avoidance

Radar sensors are used in many industries for collision detection and obstacle avoidance

Collision warning radar in the automotive sector

Radar sensors are now used in many industries and applications for collision avoidance to safeguard against accidents, prevent unplanned downtime and achieve more productivity. Radar sensors play an important role, particularly in the automotive sector: They are used as parking aids, for distance warning systems, for adaptive cruise control and as cross-traffic alarm systems.

Radar sensors are not only found in cars: radar technology has now also become established for trucks – e. g. for collision detection and obstacle avoidance when parking and maneuvering trucks at the loading ramp or in parking bays. Using collision warning radars, trucks can safely prevent collision-related damages as well as severe accidents.

Truck collision warning at the loading dock
Truck collision warning at the loading dock

Collision avoidance in transport & logistics

Radar sensors also help avoid accidents and prevent production downtime in the transport sector. When operating bridge or gantry cranes, for example, the radar sensor for collision protection detects the distance between two bridge cranes on the crane runway. In order to prevent collisions, the crane speed is gradually reduced in defined distance zones until an emergency stop occurs in the protection zone.

Collision avoidance for cranes with radar sensors
Collision avoidance for cranes with radar sensors

Collision detection in mining

In mining, collisions between mining vehicles and large mobile machines endanger smooth mining operations. Radar sensors detect obstacles from dump trucks, wheel loaders or drilling rigs even in adverse conditions and prevent collisions and severe accidents.

Collision & obstacle avoidance in the mining industry
Collision & obstacle avoidance in the mining industry

Collision & obstacle avoidance in agriculture

The demanding conditions of agriculture with poor visibility, dust, steam, smoke, rain or vibrations require very reliable sensor solutions for collision protection. Radar sensors are not only used to avoid collisions on tractors, but also for obstacle detection and safe positioning of manure or stable robots in livestock farming.

Obstacle avoidance of stable robots
Obstacle avoidance of stable robots


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