Traffic Sign Recognition Systems

Basic Description

Traffic Sign Recognition (TSR) systems employ vehicle mounted cameras that identify traffic signs while driving on the road. Typically, these systems recognize speed limit signs, stop signs and warning signs such as pedestrian crossing, railroad crossing etc. Their primary function is to inform the driver of recent traffic signs that may have been missed due to distraction or inattentiveness. An on-board camera scans the roadside for signs. Real-time image processing software identifies, interprets and displays them on a panel on the vehicle dashboard. TSR systems perform the following basic functions:

1. Detection to identify regions of interest in an image where a traffic sign is likely to be found
2. Tracking of the detected region of interest
3. Classification of the traffic sign based on internal datasets and neural network algorithms.

After the classification is done, the system informs the driver by displaying a symbol representing the recognized sign.

Vision-based TSR systems have some recognition challenges, including:

• Variation of lighting conditions
• Weather conditions (rain, fog, etc)
• Occluded signs (by trees or by other signs in urban areas)
• Image distortion due to the movement and vibration of the vehicle.

For these reasons other technologies, like RFID communication-based systems, are being explored in order to improve upon or complement camera-based TSR systems. Signs that communicate with vehicles using V2V and V2I communications are also likely to play a role in traffic sign recognition systems in the not-too-distant future.

Eventually, traffic sign recognition systems will provide information to other automotive electronic systems such as adaptive cruise control (ACC) and safety systems in order to expand their capabilities. For example, when used in conjunction with ACC, the TSR system could recognize the speed limit, warn the driver if he/she is driving too fast and automatically match the vehicle to the posted speed limit without driver input.

Sensors

Camera

Actuators

Dashboard display or head-up displays

Data Communications

Typically CAN and potentially RFID and DSRC

Manufacturers

Autoliv, Continental, Mobileye, NVIDIA, Toshiba

For More Information

[1] Traffic Sign Recognition, Wikipedia.

[2] Continental Traffic Sign Recognition, YouTube, June 16, 2010.

[3] Ford Focus - Traffic Sign Recognition, YouTube, Jan. 18, 2011.

[4] 2013 Volvo V40 - Road Sign Information, YouTube, Jul. 10, 2012.

[5] VW Golf 7 - Traffic Sign Recognition, YouTube, May 20, 2013.

[6] Bosch Road Sign Recognition, YouTube, Sep. 9, 2013.