DECIVEL - Kinematic Determination of Track and Linear Structures

ecorailPortada_ok FEDER
Start: 01 January 2012
End: 31 December 2013
Funding: Catalan
Status: Due
Division: Geomatics
Department: Geodesy and Navigation (GEON)
Code: PROVA’T call number 2011-014

The objective of DECIVEL is to build a pre-commercial product of a [railway] kinematic high-precision track geometry system together with the company Al-Top. The product will consist of the tight integration of Al-Top “RM3D Light” trolley and of an evolution of the Institute of Geomatics experimental prototypes mTAG (miliTAG) hardware and NAVEGA software.

With RM3D+DECIVEL the geometry (position coordinates and attitude angles) of rail tracks can be accurately and reliably determined at productivity rates far higher –and therefore far cheaper– than ever before. This has an impact on the quality of track geometry and, at the end of the value chain, on the speed and safety of trains and overall quality of public transportation.

DECIVEL is an advanced time-Position-Velocity-Attitude (tPVA) technology based on

  • research results of the Institute of Geomatics in the area of INS/GNSS integration
  • and on recent advances in the miniaturization of sensing technology (IMUs below 50 g weight).

DECIVEL aims at being a game changer; i.e., at redefining high-accuracy surveying of rail track geometry by transforming the static step-by-step traditional procedure –based on static total station surveying methods– into a new kinematic one based on an integration of redundant low-cost IMUs and GNSS carrier-phase receivers. RM3D + DECIVEL will be commercialized as the high-end option of RM3D and will leverage the already existing RM3D manufactured and distributed by Al-Top worldwide.

CONCEPT

Track geometry surveying is a measurement and parameter determination method to estimate the so-called track geometry parameters: track gauge, track cant, transition curve and superelevation ramp, horizontal curve radius and vertical curve radius and gradient. Traditional track geometry surveying is static or semi-kinematic. Track geometry with DECIVEL is a full kinematic surveying method.

(The track gauge is the distance between the two rails. The cant or superelevation is the difference between the rails’ heights. Transition curves –clothoids– connect tangent tracks to circular curves or circular curves to circular curves. Transition curves introduce cant via superelevation ramps. A superelevation ramp is a section of the track where the cant changes gradually. A circular curve, horizontal or vertical, is characterized by its radius. Its gradient describes the steepness of the tracks.)

Typically, 3- and 4-wheel trolleys are equipped with inclinometers, gauge-distance meters and surveying total stations that, together with previously surveyed dense geodetic networks, can acquire measurements that are later transformed into the track geometry parameters.

The DECIVEL concept is based on four ideas. With the exception of the track gauge,

  1. all track geometry parameters can be derived from the trolley tPVA trajectory (validated by the GeoTRAM project);
  2. the combined use of GPS, GLONASS, Galileo and other new GNSS signals will represent a significant advantage for tPVA determination in railway corridor environments (validated in the ENCORE project and in the general GNSS literature);
  3. the tPVA trajectory can be optimally determined with INS/GNSS close and tight integration from inertial observations (linear accelerations and angular velocities measured by the IMU) and satellite observations (carrier phases measured by a GNSS receiver) (validated in the IADIRA and ATENEA projects);
  4. redundant IMU observations acquired from sets of multiple low-cost new-generation IMUs can replace higher grade IMUs if appropriate stochastic modelling that takes into account dynamics and appropriate estimation methods are used

… acquired from a moving platform. In other words, given a time series of 3D positions, velocities and angular attitudes of the trajectory travelled by the navigation centre of the trolley, all but one track geometry parameters can be derived by simple transformations and the system calibration parameters.

In DECIVEL, the trolley is moved and driven by a walking operator. For less demanding applications or with heavier trolleys, it can be towed by a vehicle along the tracks.

The proposed concept can be complemented with odometers, imaging (cameras) and ranging (LiDAR) sensors for an extended corridor mapping capability and to compensate for GNSS unavailability (tunnels) or multipath environments. Note that the RM3D system is already equipped with sensors to provide additional parameters of interest like tracks roughness. DECIVEL can be used also for geometry determination of other transport corridors.

OTHER PARTICIPANTS:

  • UPC
  • Calero, David
  • Fernandez, Enric