Universidad de Alcalá-OTRI

Method and Sensor system for the detection of trains’ axles using fiber optics and time of flight cameras.

Posted by Universidad de Alcalá-OTRIResponsive · Patents for licensing · Spain

Summary of the technology

GEINTRA is a Spanish research group from the Department of Electronics of the University of Alcala. The group has developed a method and a sensor system for the detection and counting of the train’s axles. This sensor may be used to verify the integrity and speed of the railway convoys. This method and sensor system is characterized by its high auscultation speed. With this solution the measurements are made without physical contact with any element of the train, it has total immunity to electromagnetic interference (absence of electronics in the pathway) and to the sensor vibration. The group seeks railway related companies to achieve licensing agreements with technical collaborations and commercial agreements.

Universidad de Alcalá-OTRI

New and innovative aspects

Axles detector without any electronics  included in the track

Completely immune to electromagnetic interference and sensor’s vibration

Main advantages of its use

- Significantly increases the safety in railway transport.

- No electronics in railway are required.

- The system is immune to electromagnetic interference.

- There is no mechanical wear of the components.

- The system is immune to vibration.


Nowadays there are rail systems solutions to detect the train axles. One of which is the use of electromechanical and optical pedals which sends out an electrical signal when it is pressed by a wheel. Those solutions have the disadvantage that the physical contact with the wheels or track causes physical wear and the life expectancy is short. Also in high-speed trains it may skip the step of consecutive axles due to the inertia of the mechanical parts of the sensors.

Other solutions, which do not require physical contact with the trains, are electromagnetic sensors, which are not commonly used because they have problems related to the difficulty of their location. There are also possible faults arising from their sensitivity to the relative position of the transmitter, the receiver and the vibration. In addition, those systems can suffer electromagnetic interferences by the surrounding environment, so that they do not meet the reliability requirements demanded by the railway systems. In some cases they require electronics on track, which is another negative factor in its detection reliability. Eliminating electronics in the track, together with the immunity to electromagnetic interference systems are two of the priority criteria on any safety-related system in railway environments.

In order to resolve those problems, a non-invasive optical sensing system has been designed which detects the wheels without including any electronics in the tracks. This system is completely immune to electromagnetic interferences. Furthermore, by the method used for the measurements is immune to the sensor system vibration.

The invention proposed is based on a millisecond detection precision at the moment when a wheel passes through the point where the optical sensor head is located. To get that objective, the system uses a time of flight camera, an infrared light emitting source, an optical fiber bundle, an optical head, a separator or splitter, two optical fiber bundles terminals, a focusing optics to the time of flight camera, a focusing optics to the emitting source of light and a synchronization card.

The time of flight camera functioning is based on the principle that each of the captured pixels determines the distance from the sensor to the object. Furthermore, this type of camera captures information regarding the light intensity that reaches each pixel, providing two arrays of data, one corresponding to the intensity levels and other one of distances between a point in the scene and the sensor.

The light emitter work in the infrared spectrum to ensure day and night system’s effectiveness even in extreme light conditions. Furthermore, strategies which reduce the effect of ambient lighting are used.

From the data arrays captured with the time of flying camera, the system calculates the instant in which each of the wheels passes through the point where the optical sensor head is located.


  • Detection and counting of the train’s axles

Intellectual property status

Patent applied

Secret know how

Current development status

Development phase

Desired business relationship

The group seeks railway related companies to achieve licensing agreements with technical collaborations and commercial agreements.

Related keywords

  • Applications for Transport and Logistics
  • System and transportation
  • Railway Vehicles
  • Sensors for cars and transport
  • Railway Transport
  • Fibre Optics
  • Industrial measurement and sensing equipment
  • axles detector
  • axles sensor
  • Fiber optic
  • time of flight sensor.

About Universidad de Alcalá-OTRI

Research & Technology Organization from Spain

The Technology Transfer Office at Alcalá University serves as a liaison between the University and its socioeconomic environment in terms of research and innovation. It encorages collaboration between research groups from universities and companies/institutions, with the objective to promote and commercialize research results and scientific capabilities.

Some of the services offered by this office are specified in the following list:

- Promotion of R & D and improvement of the relationships with companies.
- Promote the participation in R & D projects applicants to public calls (regional, national and European).
- Advising, processing and monitoring of patents and other forms of industrial protection.
- Support in the negotiation of contracts and agreements for R&D&i

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