Track Defects Diagnostics System
TDDS

TDDS is based on the use of inertial measurement units (IMU) mounted on the axle boxes of the bogie. It provides contactless measurement of railway surface flaws and short-wave roughnesses on the track in real time at a speed up to 350 km/h.

Track defects diagnostic system (TDDS) is a RailwayTrack measuring subsystem which is based on the use of inertial micromechanical units (IMU) mounted on the axle boxes of the bogie. It provides contactless measurement of railway surface flaws and short-wave roughnesses on the track in real time at a speed of up to 350 km/h.

TDDS features a new method of rail surface short irregularities control. These short irregularities originate from metal chipping on the rail surface caused by acceleration and braking of the car. Until now short irregularities were detected visually and using hand tools, therefore the performance was low. TDDS implementation allows to completely automatize the rail surface short irregularities diagnostic procedure.

It should be mentioned that in addition to the rail surface irregularities similar defects occur on the roll surface of the wheel, which is very important in the context of traditional track geometric parameters measurement. Therefore, the algorithm of TDDS subsystem executes the self-calibration of wheel geometry on-line.

Due to the low cost of micromechanical sensors the regular passenger or freight trains can be equipped by such subsystem.

Four IMUs based on inertial MEMS-sensors are mounted directly on axle-boxes of bogie. Being installed closely to the rail IMU is sensitive to the wheel dynamics caused by surface defects. Suspected irregularities are compared with the video records. The video system for monitoring the track defects is based on digital video cameras and is mounted on the truck frame between the wheel pairs.

Rail surface defects	Accuracy
Corrugations, wheelslip surface defects, squats, wheelburns	0.5 mm
Car-Track Dynamic Interaction	Range
Rate	± 200 °/s
Acceleration	± 20 g and ± 50 g

Operating Parameters
Speed range	5 ... 350 km/h
Data output rate	4 kHz
Interface	USB, Ethernet, etc
Supply voltage	11 ... 34 V DC, 32 W
Operating system	Windows / Linux
Operating temperature	-40° C ... +60° C