Abstract: The position change of wheel rail contact point can directly reflect the wheel-rail contact.
Aiming at the disadvantages of current camera monitoring method which is difficult to fully capture
the position of the wheel rail contact point, a kind of wheel relative sliding image detection system is
designed based on laser source. The system combines a camera with a laser source. The camera and
laser source which keep a certain angle to the ground are installed on the bogie to convert wheel
relative sliding into the inside rail surface laser spot extraction. The experimental results show that the
system can real-time display and store the data of wheel relative sliding. And it has very important
significance to the study of high speed locomotive stability and safety.

Key words: wheel-rail contact point, wheel-rail lateral relative displacement, laser spot center, laser
source