Vehicle classification using lasertechnology

With its vehicle classification devices “TOPO”, RTB has already set the standards for gathering and evaluating traffic data. In order to expand the possibilities for classification and to fulfill requirements even better, the laser-based vehicle classification now arrives as a worldwide innovation.

By using an ingenious application of modern laser technology, RTB is the only company in the world capable of classifying vehicles on multi-lane streets from the edge of the street. The system also detects partially or totally masked vehicles. The “secret recipe” is the application of so-called multi-beam-LIDAR-sensors, which detect vehicles on the street from the right side of the street.

One sensor is aimed in a 90° angle to the street, so that it can detect the lateral height profile and allocate the vehicles to the appropriate lane. The other sensor is aimed to detect vehicles from the rear and the right side. This sensor tracks the further travel of the vehicles and determines their speed using a tracking algorithm. The system combines the measurement data from both sensors making an exact classification possible as shown below:

  • Car
  • Car + trailer
  • Motorcycle
  • Delivery van
  • Delivery van + trailer
  • Truck
  • Truck + trailer
  • Semi-trailer truck
  • Bus
  • Bus + trailer

The new development is funded in part within the framework of the Central Innovation Program Mid-size Companies (ZIM) of the Federal Ministry for Economy. This support motivates all the associates even more to continue the current path to success. Since the start of the project in June 2012, the development has been making very good progress. During the international conference on the topic “Vehicle Classification & Traffic Monitoring” which took place at RTB, the lead engineer, Thomas Eisenbach, presented the current system, which consists of two multi-beam LIDAR sensors and an industrial PC.

The goal of further development is to initiate a mobile vehicle classification system for use on multi-lane streets. The industrial PC is to be replaced by RTB’s own signal processing hardware in order to significantly reduce energy consumption. In addition, the housing will be designed to be less obvious.

Technical Background Information

LIDAR, stands for “Light Detecting And Ranging”, and describes detection using light and the distance measurement it makes possible. The LIDAR sensors transmit pulsated, invisible infrared laser beams. If this light is reflected by an object and is then picked up by the receiver of the LIDAR sensor, the system can determine the position of the object using so-called elapsed time measurement. The sensor measures the time which the light needs for the path to and from the object. Since the light waves move with the speed of light (300.000 km/s), the sensor can determine the distance traveled by the light and the distance to the object based on the elapsed time.

Multi-beam LIDAR sensors are simultaneously active LIDAR sensors, which can emit, receive and process several laser beams. A multi-dimensional detection (e.g. a 3D card) of the surroundings is possible without having to use a rotating mirror.