Understanding ADAS: Pedestrian Alert Systems (PAS)

Self-Driving 3D Car Concept: Person Steps on a Crosswalk, Autono

Traffic safety data reveals a sobering fact: a staggering 17% of global road-related fatalities are pedestrians. Within the dynamic landscape of automotive innovation, Pedestrian Alert Systems (PAS) have emerged as a critical component of Advanced Driver Assistance Systems (ADAS). These systems are designed to enhance road safety by actively identifying pedestrians in close proximity to the vehicle and promptly notifying the driver of potential collision risks. By offering early warnings and aiding drivers in pedestrian recognition, PAS systems play a pivotal role in enhancing road safety. In this article, we’ll deep dive into what Pedestrian Detection systems are, the technology behind them, and how they’re helping to save lives on the road today.

What are Pedestrian Alert Systems (PAS)?

ADAS Pedestrian Detection Systems are designed to identify pedestrians in or near the vehicle’s path and provide visual or audible warnings to the driver or, in some cases, intervene with automatic emergency braking to prevent a collision. These systems typically use a combination of cameras, radar, and LiDAR sensors to monitor the surroundings and detect potential hazards, including pedestrians.

It’s important to remember that Pedestrian Alert Systems come in various forms. While a PAS designed by one vehicle manufacturer may provide a warning to the driver of a detected pedestrian, a more advanced PAS system could engage other ADAS systems to take action if a warning is ignored or addressed by the time an object enters the vehicle’s path. Both examples would be classified as Pedestrian Alert Systems because of their pedestrian recognition functionality.

The Importance of Pedestrian Detection on the Road

The road can be a dangerous place, especially for pedestrians. Each year, thousands of accidents occur where pedestrians are involved, many of which occur because of a lack of driver awareness or environmental conditions. PAS systems can help us avoid these accidents by alerting drivers to nearby pedestrians they were unaware of, whether it be due to low-light conditions, inclement weather, or a blind spot. Thanks to the advanced technology this ADAS feature utilizes, PAS systems can identify threats and react quickly, often faster than a human driver would.

What Technologies Does Automatic Emergency Braking with Pedestrian Detection Use?

ADAS Sensors

Pedestrian Detection relies on a combination of sensors, such as cameras, radar, and LiDAR (Light Detection and Ranging), to monitor the vehicle’s surroundings. Each of these sensors used in Pedestrian Alert Systems operates very differently; where camera sensors provide visual data, radar uses radio waves to detect objects, and LiDAR employs laser beams for precise distance measurement. These sensors work together to create a comprehensive view of the environment surrounding the vehicle. Having a combination of different sensors is crucial in PAS because it allows the Pedestrian Detection system to function in different conditions. For example, a camera sensor may not be fully functional in heavy rain, but with LiDAR and radar still working together, the Pedestrian Alert System can still work.

Data Processing and Analysis

The data gathered by these sensors undergoes sophisticated data processing and analysis. Complex algorithms analyze the sensor data, looking for patterns and shapes that match pedestrian characteristics. This analytical process is crucial for distinguishing pedestrians from other objects and ensuring that the system does not generate false alarms.

Pedestrian Warning Alerts

Warning alerts are the first line of defense in preventing a collision when a pedestrian has been detected. Audio or visual cues are used to alert the driver of a potential hazard, allowing operators to safely maneuver their vehicles away from the pedestrian. This rapid response is particularly critical in situations where pedestrians suddenly enter the vehicle’s path.

Integration with Other ADAS Features

  1. Automatic Emergency Braking: When a Pedestrian Detection System identifies a potential collision with a pedestrian or an obstacle in the vehicle’s path, it can trigger the Automatic Emergency Braking system. AEB allows the vehicle to take immediate action and autonomously engage emergency braking to reduce the severity of impact or avoid a collision altogether.
  • Low-Speed Pre-Collision Systems: This ADAS feature is designed to detect potential collisions when a vehicle is driving at low speeds and is especially useful when parking, reversing, or in congested traffic environments. By integrating Pedestrian Detection with Low-Speed Pre-Collision Systems, vehicles can provide gentle braking or steering interventions to avoid minor collisions with pedestrians or obstacles, reducing the potential for vehicle damage and preventing injuries.

Pedestrian Detection in Cars Today

In recent years, Pedestrian Detection has become an increasingly more common PAS system in modern vehicles. Many automakers are prioritizing safety and incorporating this technology into their ADAS packages. Let’s take a noteworthy collaboration as an example: the partnership between Toyota and Subaru in the creation of the Subaru Solterra. Subaru’s Eyesight System Software, while advanced in its abilities to monitor surrounding traffic, was not robust enough to perform pedestrian detection. With the addition of Toyota’s Mono Camera setup, the two manufacturers were able to create the PAS system found in the Subaru Solterra: an advanced feature that is able to detect pedestrians and integrate with the vehicle’s other ADAS features.  

This partnership is not an isolated incident but a testament to the industry’s commitment to innovate and evolve with the goal of furthering ADAS technology and keeping everyone on the road safe. As manufacturers join forces to improve the effectiveness of pedestrian detection systems, we can expect even safer roads and fewer accidents involving pedestrians in the years to come.

How does ADAS Calibration Affect Pedestrian Detection Systems?

Calibration is the process of fine-tuning and aligning the various sensors and components within the ADAS system to ensure accurate and reliable performance. Proper calibration is crucial because it directly affects the system’s ability to detect and respond to pedestrians effectively. Here’s how calibration impacts pedestrian detection systems:

  1. Accuracy of Sensor Data: Calibration ensures that the data from cameras, radar, and lidar sensors is accurate and aligned correctly. Misaligned or inaccurate sensor data can lead to false positives or false negatives in pedestrian detection, jeopardizing safety.
  2.  Detection Range and Angle: Calibration helps optimize the detection range and angle of the sensors. If the detection range is too short, the system may not identify pedestrians in time to take corrective action. Conversely, if the range is too broad, it may result in false alarms.
  3. Environmental Adaptability: Different environmental conditions, such as varying lighting, weather, and road surfaces, can impact sensor performance. Proper calibration takes these factors into account, ensuring consistent performance in various conditions.
  4. Object Classification: Pedestrian detection systems must distinguish between pedestrians and other objects or vehicles. Calibration helps improve the system’s ability to classify objects correctly, reducing the likelihood of false alarms.


Pedestrian Alert Systems are a vital component of modern vehicle safety, offering additional protection for pedestrians and drivers alike. As an increasing number of vehicles integrate Pedestrian Detection into their ADAS suites, the demand for calibration centers becomes apparent to ensure the accurate functioning of this safety feature.

If you’re considering entering the calibration sector, our turnkey ADAS solution can help you get off the ground and running. We include everything you need to begin calibrating vehicles in your own facility, including on-site training, technician certification, and equipment. Contact us to learn more about owning and operating your own calibration center.

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